Common genetic variants of the FADS1 FADS2 gene cluster and their reconstructed haplotypes are associated with the fatty acid composition in phospholipids

Plasma n6 polyunsaturated fatty acid levels and risk for total and cause-specific mortality: A prospective observational study from the UK Biobank

BACKGROUND

The potential role of n-6 PUFAs in major health outcomes remains controversial.

OBJECTIVES

To examine the relationship between the major plasma n6 PUFA, linoleic acid (LA), as well as the non-LA n6 PUFAs, and total and cause-specific mortality.

METHODS

This was a prospective, observational, biomarker-based study in the UK Biobank. Individuals with complete information on baseline demographic, covariate and plasma PUFA levels (percent ot total fatty acids) and mortality outcomes were included (n=257,925). Multivariable-adjusted, Cox-proportional hazards models were used to predict risk of death from all-causes, and from cardiovascular disease (CVD), cancer, and other causes as a function of plasma LA and non-LA n6 levels, both continuously and by PUFA quintile (Q).

RESULTS

Comparing LA Q5 to Q1, the hazard ratio (HR, 95% CI) for total mortality was 0.80 (0.76, 0.84; p<0.001), and this was similar for all three cause-specific death categories. On the other hand, mortality HR for non-LA n6 was 1.12 (1.08,1.17; p<0.001), and this was primarily due to increased risk for non-CVD, noncancer deaths [HR 1.29 (1.19,1.40; p<0.001)]. Exploratory analyses among the eight next most common other causes of death suggested that both the decreased risk associated with higher LA and the increased risk associated with non-LA n6 were confined to deaths from respiratory and digestive diseases.

CONCLUSIONS

These findings highlight the profound differences in mortality risk related to LA and non-LA n6 PUFA levels and underscore the inappropriateness of treating n-6 PUFAs as a homogenous class with respect to health outcomes. They also support recommendations to maintain (if not increase) current LA intakes.

Genetic association between FADS and ELOVL polymorphisms and the circulating levels of EPA/DHA in humans: a scoping review

BACKGROUND

Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are two omega-3 fatty acids that can be synthesized out of their precursor alpha-linolenic acid (ALA). FADS and ELOVL genes encode the desaturase and elongase enzymes required for EPA and DHA synthesis from ALA; however, single nucleotide polymorphisms (SNPs) in FADS and ELOVL genes could modify the levels of EPA and DHA synthesized from ALA although there is no consensus in this area. This review aims to investigate EPA and DHA circulating levels in human blood and their association with FADS or ELOVL.

METHODS

PubMed, Cochrane, and Scopus databases were used to identify research articles. They were subsequently reviewed by two independent investigators.

RESULTS

Initially, 353 papers were identified. After removing duplicates and articles not meeting inclusion criteria, 98 full text papers were screened. Finally, this review included 40 studies investigating FADS and/or ELOVL polymorphisms. A total of 47 different SNPs in FADS genes were reported. FADS1 rs174537, rs174547, rs174556 and rs174561 were the most studied SNPs, with minor allele carriers having lower levels of EPA and DHA. SNPs in the FADS genes were in high linkage disequilibrium. SNPs in FADS were correlated with levels of EPA and DHA. No conclusion could be drawn with the ELOVL polymorphisms since the number of studies was too low.

CONCLUSION

Specific SNPs in FADS gene, such as rs174537, have strong associations with circulating levels of EPA and DHA. Continued investigation regarding the impact of genetic variants related to EPA and DHA synthesis is warranted.

Patterns of perinatal polyunsaturated fatty acid status and associated dietary or candidate-genetic factors

Perinatal exposure to omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) can be characterized through biomarkers in maternal or cord blood or breast milk. Objectives were to describe perinatal PUFA status combining multiple biofluids and to investigate how it was influenced by dietary intake during pregnancy and maternal FADS and ELOVL gene polymorphisms. This study involved 1,901 mother-child pairs from the EDEN cohort, with PUFA levels measured in maternal and cord erythrocytes, and colostrum. Maternal dietary PUFA intake during the last trimester was derived from a food frequency questionnaire. Twelve single-nucleotide polymorphisms in FADS and ELOVL genes were genotyped from maternal DNA. Principal component analysis incorporating PUFA levels from the three biofluids identified patterns of perinatal PUFA status. Spearman's correlations explored associations between patterns and PUFA dietary intake, and linear regression models examined pattern associations with FADS or ELOVL haplotypes. Five patterns were retained: "High omega-3 LC-PUFAs, low omega-6 LC-PUFAs"; "Omega-6 LC-PUFAs"; "Colostrum LC-PUFAs"; "Omega-6 precursor (LA) and DGLA"; "Omega-6 precursor and colostrum ALA". Maternal omega-3 LC-PUFA intakes were correlated with "High omega-3 LC-PUFAs, low omega-6 LC-PUFAs" (r(DHA) = 0.33) and "Omega-6 LC-PUFAs" (r(DHA) = -0.19) patterns. Strong associations were found between FADS haplotypes and PUFA patterns except for "High omega-3 LC-PUFAs, low omega-6 LC-PUFAs". Lack of genetic association with the "High omega-3 LC-PUFAs, low omega-6 LC-PUFAs" pattern, highly correlated with maternal omega-3 LC-PUFA intake, emphasizes the importance of adequate omega-3 LC-PUFA intake during pregnancy and lactation. This study offers a more comprehensive assessment of perinatal PUFA status and its determinants.

Maternal and Offspring Fatty Acid Desaturase Variants, Prenatal DHA Supplementation, and Dietary n-6:n-3 Fatty Acid Ratio in Relation to Cardiometabolic Health in Mexican Children

BACKGROUND

Single-nucleotide polymorphisms (SNPs) in fatty acid desaturase (FADS) genes may modify dietary fatty acid requirements and influence cardiometabolic health (CMH).

OBJECTIVES

We evaluated the role of selected variants in maternal and offspring FADS genes on offspring CMH at the age of 11 y and assessed interactions of genotype with diet quality and prenatal docosahexaenoic acid (DHA) supplementation.

METHODS

We used data from offspring (n = 203) born to females who participated in a randomized controlled trial of DHA supplementation (400 mg/d) from midgestation to delivery. We generated a metabolic syndrome (MetS) score from body mass index, high-density lipoprotein cholesterol, triglycerides, systolic blood pressure, and fasting glucose and identified 6 distinct haplotypes from 5 offspring FADS SNPs. Dietary n-6 (ω-6):n-3 fatty acid ratios were derived from 24-h recall data (n = 141). We used generalized linear models to test associations of offspring diet and FADS haplotypes with MetS score and interactions of maternal and offspring FADS SNP rs174602 with prenatal treatment group and dietary n-6:n-3 ratio on MetS score.

RESULTS

Associations between FADS haplotypes and MetS score were null. Offspring SNP rs174602 did not modify the association of prenatal DHA supplementation with MetS score. Among children with TT or TC genotype for SNP rs174602 (n = 88), those in the highest n-6:n-3 ratio tertile (>8.61) had higher MetS score relative to the lowest tertile [<6.67) (Δ= 0.36; 95% confidence interval (CI): 0.03, 0.69]. Among children with CC genotype (n = 53), those in the highest n-6:n-3 ratio tertile had a lower MetS score relative to the lowest tertile (Δ= -0.23; 95% CI: -0.61, 0.16).

CONCLUSIONS

There was evidence of an interaction of offspring FADS SNP rs174602 with current dietary polyunsaturated fatty acid intake, but not with prenatal DHA supplementation, on MetS score. Further studies may help to determine the utility of targeted supplementation strategies and dietary recommendations based on genetic profile.

Evaluating the relationship between the nutrient intake of lactating women and their breast milk nutritional profile: a systematic review and narrative synthesis

Maternal diet influences breast milk nutritional profile; however, it is unclear which nutrients and contaminants are particularly responsive to short- and long-term changes in maternal intake, and the impact of specific exclusion diets, such as vegan or vegetarian. This study systematically reviewed the literature on the effects of maternal nutrient intake, including exclusion diets, on both the nutrient and contaminant content of breast milk. The electronic databases, PubMed, CENTRAL, Web of Science and CINALH were systematically searched until 4 June 2023, with additionally searches of reference lists (PROSPERO, CRD42020221577). The quality of the studies was examined using Cochrane Risk of Bias tool and Newcastle-Ottawa scale. Eighty-eight studies (n 6577) met the search criteria. Due to high heterogeneity, meta-analysis was not possible. There was strong evidence of response to maternal intakes for DHA and EPA, vitamins A, E and K, iodine and Se in breast milk composition, some evidence of response for α-linolenic acid, B vitamins, vitamin C and D, ovalbumin, tyrosine and contaminants, and insufficient evidence to identify the effects arachidonic acid, Cu, Fe, Zn and choline. The paucity of evidence and high heterogeneity among studies reflects the need for more high-quality trials. However, this review identified the importance of maternal intake in the nutritional content of breast milk for a wide range of nutrients and supports the recommendation for supplementation of DHA and vitamin B12 for those on restrictive diets.

The role of polyunsaturated fatty acids in the neurobiology of major depressive disorder and suicide risk

Long-chain polyunsaturated fatty acids (LC-PUFAs) are obtained from diet or derived from essential shorter-chain fatty acids, and are crucial for brain development and functioning. Fundamentally, LC-PUFAs' neurobiological effects derive from their physicochemical characteristics, including length and double bond configuration, which differentiate LC-PUFA species and give rise to functional differences between n(omega)-3 and n-6 LC-PUFAs. LC-PUFA imbalances are implicated in psychiatric disorders, including major depression and suicide risk. Dietary intake and genetic variants in enzymes involved in biosynthesis of LC-PUFAs from shorter chain fatty acids influence LC-PUFA status. Domains impacted by LC-PUFAs include 1) cell signaling, 2) inflammation, and 3) bioenergetics. 1) As major constituents of lipid bilayers, LC-PUFAs are determinants of cell membrane properties of viscosity and order, affecting lipid rafts, which play a role in regulation of membrane-bound proteins involved in cell-cell signaling, including monoaminergic receptors and transporters. 2) The n-3:n-6 LC-PUFA balance profoundly influences inflammation. Generally, metabolic products of n-6 LC-PUFAs (eicosanoids) are pro-inflammatory, while those of n-3 LC-PUFAs (docosanoids) participate in the resolution of inflammation. Additionally, n-3 LC-PUFAs suppress microglial activation and the ensuing proinflammatory cascade. 3) N-3 LC-PUFAs in the inner mitochondrial membrane affect oxidative stress, suppressing production of and scavenging reactive oxygen species (ROS), with neuroprotective benefits. Until now, this wealth of knowledge about LC-PUFA biomechanisms has not been adequately tapped to develop translational studies of LC-PUFA clinical effects in humans. Future studies integrating neurobiological mechanisms with clinical outcomes may suggest ways to identify depressed individuals most likely to respond to n-3 LC-PUFA supplementation, and mechanistic research may generate new treatment strategies.

Are Phe-Free Protein Substitutes Available in Italy for Infants with PKU All the Same?

Breastfeeding or standard infant formulas, alongside phenylalanine (Phe)-free protein substitutes, constitute the dietary management for infants with PKU to guarantee protein requirements are met in compliance with metabolic tolerance. This work aims to analyse the nutritional composition of Phe-free infant protein substitutes, in terms of macronutrients, micronutrients and functional components, available for PKU dietary management in Italy. A total of seven infant Phe-free protein substitutes were included in this review, six powder and one liquid. A second analysis was conducted to compare them to the composition of formulas intended for healthy infants, taking into consideration the Commission Delegated Regulation (EU) 2016/127 and Commission Delegated Regulation (EU) 2016/128 for micronutrients. The analysis revealed heterogeneity among protein substitutes suitable for infants with PKU. The energy and protein equivalents (P.Eq.) content are different; all of the substitutes contain docosahexaenoic acid (DHA) and arachidonic acid (ARA), while eicosapentaenoic acid (EPA), fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS), human milk oligosaccharides (HMOs) and nucleotides are not present in all the substitutes. More attention should be paid to these infant products to ensure metabolic control of PKU, and also promote proper growth, cognitive neurodevelopment, favourable gut microbiota composition, and immune system health, while reducing the risk for non-communicable diseases (NCDs).

Effects of prenatal docosahexaenoic acid supplementation on offspring cardiometabolic health at 11 years differs by maternal single nucleotide polymorphism rs174602: follow-up of a randomized controlled trial in Mexico

BACKGROUND

There is limited evidence regarding long-term effects of prenatal docosahexaenoic acid (DHA) supplementation on offspring cardiometabolic health (CMH). Inconsistent results may be attributable to variants of fatty acid desaturase (FADS) genes.

OBJECTIVE

We aimed to evaluate the effect of prenatal DHA supplementation on offspring CMH and investigate effect modification by maternal FADS2 single nucleotide polymorphism (SNP) rs174602.

METHODS

We used follow-up data from a double-blind, randomized controlled trial in Mexico in which pregnant females received 400 mg/d of algal DHA or placebo from midgestation until delivery. The study sample included 314 offspring with data at age 11 y and maternal FADS genetic data (DHA: n = 160; Placebo: n = 154). We derived a Metabolic Syndrome (MetS) score from body mass index, HDL, triglycerides, fasting glucose concentrations, and systolic blood pressure. Generalized linear models were used to evaluate the effect of the intervention on offspring MetS score and test interactions between treatment group and genotype, adjusting for maternal, offspring, and household factors.

RESULTS

Offspring MetS score did not differ significantly by treatment group. We observed evidence of effect modification by maternal SNP rs174602 (P = 0.001); offspring of maternal TT genotype who received DHA had lower MetS score relative to the placebo group (DHA (mean ± standard error of the mean (SEM)): -0.21 ± 0.11, n = 21; Placebo: 0.05 ± 0.11, n = 23; Δ= -0.26 (95% CI: -0.55, 0.04), P = 0.09); among CC maternal genotype carriers, offspring of mothers who received DHA had higher MetS score (0.18 ± 0.06, n = 62) relative to the placebo group (-0.05 ± 0.06, n = 65, Δ=0.24 (0.06, 0.41), P < 0.01).

CONCLUSION

The effect of prenatal DHA supplementation on offspring MetS score differed by maternal FADS SNP rs174602. These findings further support incorporating genetic analysis of FADS polymorphisms in DHA supplementation trials.

CLINICAL TRIAL DETAILS

This trial was registered at clinicaltrials.gov as NCT00646360.

Fatty Acids Profile and the Relevance of Membranes as the Target of Nutrition-Based Strategies in Atopic Dermatitis: A Narrative Review

Recently, the prevalence of atopic dermatitis has increased drastically, especially in urban populations. This multifactorial skin disease is caused by complex interactions between various factors including genetics, environment, lifestyle, and diet. In eczema, apart from using an elimination diet, the adequate content of fatty acids from foods (saturated, monounsaturated, and polyunsaturated fatty acids) plays an important role as an immunomodulatory agent. Different aspects regarding atopic dermatitis include connections between lipid metabolism in atopic dermatitis, with the importance of the MUFA levels, as well as of the omega-6/omega-3 balance that affects the formation of long-chain (C20 eicosanoic and C22 docosaenoic) fatty acids and bioactive lipids from them (such as prostaglandins). Impair/repair of the functioning of epidermal barrier is influenced by these fatty acid levels. The purpose of this review is to drive attention to membrane fatty acid composition and its involvement as the target of fatty acid supplementation. The membrane-targeted strategy indicates the future direction for dermatological research regarding the use of nutritional synergies, in particular using red blood cell fatty acid profiles as a tool for checking the effects of supplementations to reach the target and influence the inflammatory/anti-inflammatory balance of lipid mediators. This knowledge gives the opportunity to develop personalized strategies to create a healthy balance by nutrition with an anti-inflammatory outcome in skin disorders.

Reprogramming of rhythmic liver metabolism by intestinal clock

BACKGROUND & AIMS

Temporal oscillations in intestinal nutrient processing and absorption are coordinated by the local clock, which leads to the hypothesis that the intestinal clock has major impacts on shaping peripheral rhythms via diurnal nutritional signals. Here, we investigate the role of the intestinal clock in controlling liver rhythmicity and metabolism.

METHODS

Transcriptomic analysis, metabolomics, metabolic assays, histology, quantitative (q)PCR, and immunoblotting were performed with Bmal1-intestine-specific knockout (iKO), Rev-erba-iKO, and control mice.

RESULTS

Bmal1 iKO caused large-scale reprogramming of the rhythmic transcriptome of mouse liver with a limited effect on its clock. In the absence of intestinal Bmal1, the liver clock was resistant to entrainment by inverted feeding and a high-fat diet. Importantly, Bmal1 iKO remodelled diurnal hepatic metabolism by shifting to gluconeogenesis from lipogenesis during the dark phase, leading to elevated glucose production (hyperglycaemia) and insulin insensitivity. Conversely, Rev-erba iKO caused a diversion to lipogenesis from gluconeogenesis during the light phase, resulting in enhanced lipogenesis and an increased susceptibility to alcohol-related liver injury. These temporal diversions were attributed to disruption of hepatic SREBP-1c rhythmicity, which was maintained via gut-derived polyunsaturated fatty acids produced by intestinal FADS1/2 under the control of a local clock.

CONCLUSIONS

Our findings establish a pivotal role for the intestinal clock in dictating liver rhythmicity and diurnal metabolism, and suggest targeting intestinal rhythms as a new avenue for improving metabolic health.

IMPACT AND IMPLICATIONS

Our findings establish the centrality of the intestinal clock among peripheral tissue clocks, and associate liver-related pathologies with its malfunction. Clock modifiers in the intestine are shown to modulate liver metabolism with improved metabolic parameters. Such knowledge will help clinicians improve the diagnosis and treatment of metabolic diseases by incorporating intestinal circadian factors.

Associations between Fatty Acid Intakes and Plasma Phospholipid Fatty Acid Concentrations in the European Prospective Investigation into Cancer and Nutrition

BACKGROUND

The aim of this study is to determine the correlations between dietary fatty acid (FA) intakes and plasma phospholipid (PL) FA levels in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort.

METHODS

The dietary intake of 60 individual FAs was estimated using centre-specific validated dietary questionnaires. Plasma PL FA concentrations of these FAs were measured in non-fasting venous plasma samples in nested case-control studies within the EPIC cohort (n = 4923, using only non-cases). Spearman rank correlations were calculated to determine associations between FA intakes and plasma PL FA levels.

RESULTS

Correlations between FA intakes and circulating levels were low to moderately high (-0.233 and 0.554). Moderate positive correlations were found for total long-chain n-3 poly-unsaturated FA (PUFA) (r = 0.354) with the highest (r = 0.406) for n-3 PUFA docosahexaenoic acid (DHA). Moderate positive correlations were also found for the non-endogenously synthesized trans-FA (r = 0.461 for total trans-FA C16-18; r = 0.479 for industrial trans-FA (elaidic acid)).

CONCLUSIONS

Our findings indicate that dietary FA intakes might influence the plasma PL FA status to a certain extent for several specific FAs. The stronger positive correlations for health-enhancing long-chain PUFAs and the health-deteriorating trans-FA that are not endogenously produced are valuable for future cancer prevention public health interventions.

Multiset correlation and factor analysis enables exploration of multi-omics data

Multi-omics datasets are becoming more common, necessitating better integration methods to realize their revolutionary potential. Here, we introduce multi-set correlation and factor analysis (MCFA), an unsupervised integration method tailored to the unique challenges of high-dimensional genomics data that enables fast inference of shared and private factors. We used MCFA to integrate methylation markers, protein expression, RNA expression, and metabolite levels in 614 diverse samples from the Trans-Omics for Precision Medicine/Multi-Ethnic Study of Atherosclerosis multi-omics pilot. Samples cluster strongly by ancestry in the shared space, even in the absence of genetic information, while private spaces frequently capture dataset-specific technical variation. Finally, we integrated genetic data by conducting a genome-wide association study (GWAS) of our inferred factors, observing that several factors are enriched for GWAS hits and trans-expression quantitative trait loci. Two of these factors appear to be related to metabolic disease. Our study provides a foundation and framework for further integrative analysis of ever larger multi-modal genomic datasets.

Impact of polyunsaturated fatty acid supplementation on assisted reproductive technology outcomes: a systematic review

This review explores the impact of polyunsaturated fatty acid (PUFA) supplementation in women undergoing assisted reproductive technology (ART) on reproductive outcomes. A systematic search of English peer-reviewed journals was carried out using MEDLINE, EMBASE, and the Cochrane Library to identify articles published from January 1978 to 2021. The primary outcomes assessed included pregnancy and live birth rates. Secondary outcome measures included: (i) implantation rate; (ii) fertilisation rate; (iii) number of oocytes retrieved; (iv) number of metaphase II (MII) oocytes; (v) blastocyst conversion; and (vi) embryo quality. A total of 4 randomised control trials (RCTs) met the inclusion criteria. There is a lack of high-quality research to support widespread dietary supplementation with PUFAs in women undergoing ART. Prior to its clinical recommendation, there is a need for well-designed RCTs to facilitate an in-depth understanding of PUFA supplementation in women undergoing ART.

Omega-3 Fatty Acids Interact with DPP10 Region Genotype in Association with Childhood Atopy

Associations of omega-3 fatty acids (n-3) with allergic diseases are inconsistent, perhaps in part due to genetic variation. We sought to identify and validate genetic variants that modify associations of n-3 with childhood asthma or atopy in participants in the Vitamin D Antenatal Asthma Reduction Trial (VDAART) and the Copenhagen Prospective Studies on Asthma in Childhood 2010 (COPSAC). Dietary n-3 was derived from food frequency questionnaires and plasma n-3 was measured via untargeted mass spectrometry in early childhood and children aged 6 years old. Interactions of genotype with n-3 in association with asthma or atopy at age 6 years were sought for six candidate genes/gene regions and genome-wide. Two SNPs in the region of DPP10 (rs958457 and rs1516311) interacted with plasma n-3 at age 3 years in VDAART (p = 0.007 and 0.003, respectively) and with plasma n-3 at age 18 months in COPSAC (p = 0.01 and 0.02, respectively) in associationwith atopy. Another DPP10 region SNP, rs1367180, interacted with dietary n-3 at age 6 years in VDAART (p = 0.009) and with plasma n-3 at age 6 years in COPSAC (p = 0.004) in association with atopy. No replicated interactions were identified for asthma. The effect of n-3 on reducing childhood allergic disease may differ by individual factors, including genetic variation in the DPP10 region.

Dietary Fatty Acids and Inflammation: Focus on the n-6 Series

Among the polyunsaturated fatty acids (PUFAs), those belonging to the n-3 (or ω3) series, i.e., alpha-linolenic (ALA), eicosapentaenoic (EPA), and docosahexaenoic (DHA) acids have been studied for decades from a pharma-nutritional viewpoint, namely in relation to cardiovascular health. More recent research is focusing on n-6 PUFAs, e.g., linoleic acid (LA), whose levels of consumption are much higher than those of n-3 and that cannot be used "pharmacologically". Perhaps because of this, the biological actions of n-6 PUFAs have not been investigated in details as those of their n-3 counterparts. However, an increasing body of evidence underscores their healthful actions on the cardiovascular system. Among the critiques to n-6 PUFAs and, particularly, LA there is the fact that they are precursors of pro-inflammatory eicosanoids. Hence, the hypothesis posits that we should reduce their intakes precisely to avoid increasing systemic, low-grade inflammation, i.e., one of the major etiological agents in degenerative diseases. In this narrative review, we address the issue of whether n-6 PUFAs are indeed pro-inflammatory, we discuss the most recent evidence of their role(s) in human health and prognosis, and we conclude that adequate intakes of n-6 fatty acids are associated with better cardiovascular health and child development.

Furan fatty acid metabolite in newborns predicts risk of asthma

BACKGROUND

Intake of fish-oil and fatty fish during pregnancy has been shown to reduce the risk of childhood asthma but biomarkers of such intake are lacking.

OBJECTIVE

To establish biomarkers of prenatal fish-oil exposure from newborn dry blood spot metabolomics profiles and assess their relevance for childhood asthma risk stratification.

METHODS

The Danish COPSAC₂₀₁₀ mother-child cohort was utilized to investigate the effect of a double-blinded randomized controlled trial of fish-oil supplementation during pregnancy on dry blood spot liquid-chromatography mass spectrometry-based metabolomics profiles of 677 newborns. We thereafter investigated the association between fish-oil associated biomarkers in the newborn and development of asthma-related outcomes. Replication was sought in the independent observational COPSAC₂₀₀₀ cohort with 387 newborn metabolomics profiles.

RESULTS

The newborn metabolomics profiles differed between children in the fish-oil vs. placebo group in COPSAC₂₀₁₀ (area under the receiver operator curve = 0.94 ± 0.03, p < .001). The fish-oil metabolomics profile and the top biomarker, 3-carboxy-4-methyl-5-propyl-2-furan propanoic acid (CMPF) were both associated with a decreased risk of asthma by age 6 years (HR = 0.89, p = .002 and HR = 0.67, p = .005, respectively). In COPSAC₂₀₀₀ , newborn CMPF level was also inversely associated with asthma risk by age 6 years (HR = 0.69, p = .01). Troublesome lung symptoms and common infections in the first 3 years were also inversely associated with newborn CMPF levels in both cohorts.

CONCLUSIONS

Newborn children's blood levels of the furan fatty acid metabolite CMPF reflect fish-oil and fatty fish intake during pregnancy and are associated with a lower risk of asthma across two cohorts, which could aid newborn screening for childhood asthma.

Nutrition in inflammatory bowel diseases; Is there a role?

Nutrition is of paramount importance not only for healthy individuals, but all the more for the ones with pathologies interlinked with the diet. In that light, diet, when used accordingly can act in a protective manner in inflammatory bowel diseases. The interplay of diet and IBD is not thoroughly defined, and guidelines are a work in progress. However, significant knowledge has been gained with regard to foods and nutrients that may exacerbate or alleviate the core symptoms. Patients with IBD restrict from their diet a plethora of foods often arbitrary, thus depriving themselves from valuable constituents. Careful navigation into the newfound field of genetic variants and personalization of diet should be employed with avoidance of the Westernized diet, processed foods and additives, and focus on a holistic approach with a balanced diet rich in bioactive compounds in order to improve the quality of life of these patients and address diet-related deficiencies.

Association of Fatty Acid Desaturase 1 rs174547 Polymorphism with the Composition of Long-Chain Polyunsaturated Fatty Acids in Serum Glycerophospholipids during Pregnancy

The increase in fetal requirements of long-chain polyunsaturated fatty acids (LCPUFAs) during pregnancy alters maternal fatty acid metabolism, and therefore, fatty acid desaturase (FADS) gene polymorphisms may change blood fatty acid composition or concentration differently during pregnancy. We investigated the relationship between a FADS1 single-nucleotide polymorphism (SNP) and maternal serum LCPUFA levels in Japanese pregnant women during the first and third trimesters and at delivery. Two hundred and fifty-three pregnant women were included, and fatty acid compositions of glycerophospholipids in serum (weight %) and the FADS1 SNP rs174547 (T/C) were analyzed. LCPUFAs, including arachidonic acid (ARA) and docosahexaenoic acid (DHA), significantly decreased from the first to the third trimester of pregnancy. Furthermore, DHA significantly decreased from the third trimester of pregnancy to delivery. At all gestational stages, linoleic acid (LA) and α-linolenic acid were significantly higher with the number of minor FADS1 SNP alleles, whereas γ-linolenic acid and ARA and the ARA/LA ratio were significantly lower. DHA was significantly lower with the number of minor FADS1 SNP alleles only in the third trimester and at delivery, suggesting that genotype effects become more obvious as pregnancy progresses.

What Is the Evidence for Dietary-Induced DHA Deficiency in Human Brains?

Docosahexaenoic acid (DHA) is a major constituent of neural and visual membranes and is required for optimal neural and visual function. DHA is derived from food or by endogenous synthesis from α-linolenic acid (ALA), an essential fatty acid. Low blood levels of DHA in some westernised populations have led to speculations that child development disorders and various neurological conditions are associated with sub-optimal neural DHA levels, a proposition which has been supported by the supplement industry. This review searched for evidence of deficiency of DHA in human populations, based on elevated levels of the biochemical marker of n-3 deficiency, docosapentaenoic acid (22:5n-6). Three scenarios/situations were identified for the insufficient supply of DHA, namely in the brain of new-born infants fed with high-linoleic acid (LA), low-ALA formulas, in cord blood of women at birth who were vegetarians and in the milk of women from North Sudan. Twenty post-mortem brain studies from the developed world from adults with various neurological disorders revealed no evidence of raised levels of 22:5n-6, even in the samples with reduced DHA levels compared with control subjects. Human populations most likely at risk of n-3 deficiency are new-born and weanling infants, children and adolescents in areas of dryland agriculture, in famines, or are refugees, however, these populations have rarely been studied. This is an important topic for future research.

The FADS1 rs174550 Genotype Modifies the n-3 and n-6 PUFA and Lipid Mediator Responses to a High Alpha-Linolenic Acid and High Linoleic Acid Diets

SCOPE

The fatty acid composition of plasma lipids, which is associated with biomarkers and risk of non-communicable diseases, is regulated by dietary polyunsaturated fatty acids (PUFAs) and variants of fatty acid desaturase (FADS). We investigated the interactions between dietary PUFAs and FADS1 rs174550 variant.

METHODS AND RESULTS

Participants (n = 118), homozygous for FADS1 rs174550 variant (TT and CC) followed a high alpha-linolenic acid (ALA, 5 percent of energy (E-%)) or a high linoleic acid (LA, 10 E-%) diet during an 8-week randomized controlled intervention. Fatty acid composition of plasma lipids and PUFA-derived lipid mediators were quantified by gas and liquid chromatography mass spectrometry, respectively. The high-LA diet increased the concentration of plasma LA, but not its lipid mediators. The concentration of plasma arachidonic acid decreased in carriers of CC and remained unchanged in the TT genotype. The high-ALA diet increased the concentration of plasma ALA and its cytochrome P450-derived epoxides and dihydroxys, and cyclooxygenase-derived monohydroxys. Concentrations of plasma eicosapentaenoic acid and its mono- and dihydroxys increased only in TT genotype carriers.

CONCLUSIONS

These findings suggest the potential for genotype-based recommendations for PUFA consumption, resulting in modulation of bioactive lipid mediators which can exert beneficial effects in maintaining health.

Maternal DHA-rich n-3 PUFAs supplementation interacts with FADS genotypes to influence the profiles of PUFAs in the colostrum among Chinese Han population: a birth cohort study

Background

The single nucleotide polymorphisms (SNPs) in the fatty acid desaturases and elongases might associate with the endogenous synthesis of polyunsaturated fatty acids (PUFAs). However, the related epidemiological evidence is still conflicting. So we aimed to clearly evaluate the interactions between maternal DHA-rich n-3 PUFAs supplementation and the known 26 SNPs on the profiles of PUFAs in the colostrum using a Chinese birth cohort.

Methods

Totally, 1050 healthy mother-infant pairs were enrolled in this study at gestational 6–8 weeks when they established their pregnancy files at Fuxing Hospital affiliated to Capital Medical University in Beijing from January to December 2018. Meanwhile, their venous blood samples were obtained for DNA extraction to detect the genotypes of SNPs in the Fads1, Fads2, Fads3, Elovl2 and Elovl5 using the Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry. Then the colostrum samples were collected to determine the profiles of PUFAs by gas chromatography.

Results

Maternal DHA-rich n-3 PUFAs supplementation from the early and middle pregnancy could reduce the infant BMI at birth, and impact the profiles of PUFAs in the colostrum, as higher n-3 PUFAs (EPA, DHA, DHA/ALA and DHA/EPA), lower n-6 PUFAs (AA and AA/LA) and ∑-6/n-3ΣPUFAs. Moreover, there were significant correlations between multiple SNPs and the profiles of n-6 PUFAs (rs76996928 for LA, rs174550, rs174553 and rs174609 for AA, rs174550 and rs76996928 for AA/LA) and n-3 PUFAs in the colostrum (rs174448, rs174537, rs174550, rs174553, rs174598, rs3168072, rs174455 and rs174464 for ALA, rs174550, rs174553 and rs174598 for EPA, rs174455 and rs174464 for DHA, rs174448 and rs3168072 for DHA/EPA) using the multiple linear regressions by adjusting the maternal age, gestational week, mode of delivery, infant sex and BMI at birth, and all these above significant SNPs had the cumulative effects on the profiles of PUFAs. Furthermore, the pairwise comparisons also showed the meaningful interactions between maternal DHA-rich n-3 PUFAs supplementation and related genotypes of SNPs (rs76996928 for LA, rs174598 for EPA, rs174448 for DHA and DHA/EPA) on the contents of PUFAs in the colostrum.

Conclusions

Results from this birth cohort study proved that the pregnant women with the following SNPs such as Fads3 rs174455 T, Fads3 rs174464 A and Fads1 rs174448 G alleles should pay more attention on their exogenous DHA supplementation from the early and middle pregnancy for the blocked endogenous synthesis.

Trial registration: This study was approved by the Ethics Committee of Beijing Pediatric Research Institution, Beijing Children’s Hospital affiliated to Capital Medical University (2016–08), which was also registered at the website of http://www.chictr.org.cn/showproj.aspx?proj=4673 (No: ChiCTR-OCH-14004900).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12986-022-00683-3.

Interaction among dietary n-3 and n-6 polyunsaturated fatty acid intake, fatty acid desaturase 2 genetic variants, and low-density lipoprotein cholesterol levels in type 2 diabetes patients

AIMS/INTRODUCTION

Fatty acid desaturase (FADS) genetic polymorphisms are strongly correlated with the risk of dyslipidemia and cardiovascular disease. In this study, we examined the impact of FADS1 and FADS2 genetic variants on plasma lipid status, and assessed interactions between FADS genetic polymorphisms and plasma n-3/n-6 fatty acids regarding lipid status within a population of 816 Taiwanese patients with type 2 diabetes.

MATERIALS AND METHODS

Selected tag single-nucleotide polymorphisms (FADS1 rs174546 [T/C]; FADS2 rs174602 [A/G] and rs2072114 [A/G]) were genotyped (n = 816).

RESULTS

The distribution of genotypes were compared with reports publicly available in the Genome Aggregation Database for East Asian populations (https://gnomad.broadinstitute.org). In the subgroup of patients not taking lipid-lowering medications (n = 192), we observed that the G allele of FADS2 rs174602 was statistically significantly correlated with lower low-density lipoprotein cholesterol (LDL-C) concentrations (P = 0.001), whereas the G allele of rs2072114 was marginally associated with LDL-C concentrations (P = 0.091). Using a general linear model adjusted for confounding factors, statistically significant interactions (P = 0.016) between single-nucleotide polymorphisms in rs2072114 and a low alpha-linolenic acid (18:3n-3)/linoleic acid (18:2n-6) ratio; the G allele correlated with lower LDL-C levels among individuals with a low alpha-linolenic acid/linoleic acid ratio. Interaction between rs174602 single-nucleotide polymorphisms and low alpha-linolenic acid/linoleic acid values on LDL-C was only marginally significant (P = 0.063).

CONCLUSIONS

Our results show the role of n-3/n-6 dietary polyunsaturated fatty acids in modifying the effects of genetic susceptibility on lipoprotein concentrations in patients with type 2 diabetes. Our findings highlight the potential of interventions with dietary polyunsaturated fatty acids regarding developing individualized prevention strategies for type 2 diabetes presenting with co-occurring dyslipidemia and cardiovascular diseases.

Novel Interactions of Myristic Acid and FADS3 Variants Predict Atopic Dermatitis among Indonesian Infants

Fatty acids exert a range of different biological activities that could be relevant in the development of atopic dermatitis (AD). This study investigated the association of glycerophospholipid fatty acids (GPL-FA) with AD, and their interactions with single nucleotide polymorphisms (SNP) of the FADS1-3 gene cluster. Among 390 infants of the Indonesian ISADI study, GPL-FA were measured in umbilical plasma (P-0y) and in buccal cells at birth (B-0y), and again in buccal cells at AD onset or one year (B-1y). Prospective and cross-sectional associations with AD were assessed by logistic regression. Interactions of GPL-FA with 14 SNP were tested assuming an additive model. AD was diagnosed in 15.4% of participants. In B-1y, C18:2n-6 was inversely associated with AD; and positive associations were observed for C18:1n-9, C20:4n-6, C22:6n-3 and C20:4n-6/C18:2n-6. There were no prospective associations with AD, however, a significant interaction between the SNP rs174449 and B-0y C14:0 (myristic acid) was observed. This study indicates that Indonesian infants with AD have increased rates of endogenous long-chain polyunsaturated fatty acid production, as well as higher C18:1n-9 levels. GPL-FA measured at birth do not predict later AD incidence; however, genotype interactions reveal novel effects of myristic acid, which are modified by a FADS3 variant.

Genes regulating levels of ω-3 long-chain polyunsaturated fatty acids are associated with alcohol use disorder and consumption, and broader externalizing behavior in humans

BACKGROUND

Individual variation in the physiological response to alcohol is predictive of an individual's likelihood to develop alcohol use disorder (AUD). Evidence from diverse model organisms indicates that the levels of long-chain polyunsaturated omega-3 fatty acids (ω-3 LC-PUFAs) can modulate the behavioral response to ethanol and therefore may impact the propensity to develop AUD. While most ω-3 LC-PUFAs come from diet, humans can produce these fatty acids from shorter chain precursors through a series of enzymatic steps. Natural variation in the genes encoding these enzymes has been shown to affect ω-3 LC-PUFA levels. We hypothesized that variation in these genes could contribute to the susceptibility to develop AUD.

METHODS

We identified nine genes (FADS1, FADS2, FADS3, ELOVL2, GCKR, ELOVL1, ACOX1, APOE, and PPARA) that are required to generate ω-3 LC-PUFAs and/or have been shown or predicted to affect ω-3 LC-PUFA levels. Using both set-based and gene-based analyses we examined their association with AUD and two AUD-related phenotypes, alcohol consumption, and an externalizing phenotype.

RESULTS

We found that the set of nine genes is associated with all three phenotypes. When examined individually, GCKR, FADS2, and ACOX1 showed significant association signals with alcohol consumption. GCKR was significantly associated with AUD. ELOVL1 and APOE were associated with externalizing.

CONCLUSIONS

Taken together with observations that dietary ω-3 LC-PUFAs can affect ethanol-related phenotypes, this work suggests that these fatty acids provide a link between the environmental and genetic influences on the risk of developing AUD.

Fatty acid desaturase 1 (FADS1) is a cancer marker for patient survival and a potential novel target for precision cancer treatment

Fatty Acid Desaturase-1 (FADS1) or delta 5 desaturase (D5D) is a rate-limiting enzyme involved in the biosynthesis of long-chain polyunsaturated fatty acids (LC-PUFAs), i.e., arachidonic acid (ARA) and eicosapentaenoic (EPA). These LC-PUFAs and their metabolites play essential and broad roles in cancer cell proliferation, metastasis, and tumor microenvironment. However, the role of FADS1 in cancers remains incompletely understood. Utilizing The Cancer Genome Atlas (TCGA) database, we explored the role of FADS1 across different cancer types using multiple bioinformatics and statistical tools. Moreover, we studied the impact of a FADS1 inhibitor (D5D-IN-326) on proliferation of multiple cancer cell lines. We identified that FADS1 gene is a predictor for cancer survival in multiple cancer types. Compared to normal tissue, the mRNA expression of FADS1 is significantly increased in primary tumors while even higher in metastatic and recurrent tumors. Mechanistically, pathway analysis demonstrated that FADS1 is associated with cholesterol biosynthesis and cell cycle control genes. Interestingly, FADS1 expression is higher when TP53 is mutated. Tumors with increased FADS1 expression also demonstrated an increased signatures of fibroblasts and macrophages infiltration among most cancer types. Our in vitro assays showed that D5D-IN-326 significantly inhibited cell proliferation of kidney, colon, breast, and lung cancer cell lines in a dose-dependent manner. Lastly, single nucleotide polymorphisms (SNPs) which are well-established expression quantitative trait loci (eQTLs) for FADS1 in normal human tissues are also significantly correlated with FADS1 expression in tumors of multiple tissue types, potentially serving as a marker to stratify cancer patients with high/low FADS1 expression in their tumor tissue. Our study suggests that FADS1 plays multiple roles in cancer biology and is potentially a novel target for precision cancer treatment.

α-linolenic acid interconversion is sufficient as a source of longer chain ω-3 polyunsaturated fatty acids in humans: An opinion

α-linolenic acid (αLNA) conversion into the functionally important ω-3 polyunsaturated fatty acids (PUFA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), has been regarded as inadequate for meeting nutritional requirements for these PUFA. This view is based on findings of small αLNA supplementation trials and stable isotope tracer studies that have been interpreted as indicating human capacity for EPA and, in particular, DHA synthesis is limited. The purpose of this review is to re-evaluate this interpretation. Markedly differing study designs, inconsistent findings and lack of trial replication preclude robust consensus regarding the nutritional adequacy of αLNA as a source of EPC and DHA. The conclusion that αLNA conversion in humans is constrained is inaccurate because it presupposes the existence of an unspecified, higher level of metabolic activity. Since capacity for EPA and DHA synthesis is the product of evolution it may be argued that the levels of EPA and DHA it maintains are nutritionally appropriate. Dietary and supra-dietary EPA plus DHA intakes confer health benefits. Paradoxically, such health benefits are also found amongst vegetarians who do not consume EPA and DHA, and for whom αLNA conversion is the primary source of ω-3 PUFA. Since there are no reported adverse effects on health or cognitive development of diets that exclude EPA and DHA, their synthesis from αLNA appears to be nutritionally adequate. This is consistent with the dietary essentiality of αLNA and has implications for developing sustainable nutritional recommendations for ω-3 PUFA.

Maternal erythrocyte fatty acid composition as a predictive marker for pregnancy health

Pregnancy is accompanied by a surge in demand for fatty acids (FAs) in order to support maternal health, as well as fetal growth and development. Of particular demand is essential for long-chain polyunsaturated FAs. FAs are primarily obtained from dietary sources and are distributed in the body. In comparison with the use of self-reporting approaches, measuring the FA levels within different blood compartments can present a more accurate image of nutritional, and thus tissue, FA composition. Hence, the FA profile of plasma or serum is commonly used for physiological analyses. Nevertheless, plasma and serum FAs are not yet incorporated into cell membranes, and consequently may not be a suitable reflection of the FA status of body tissues. The evaluation of erythrocyte FA levels offers a superior possibility for the following reasons: the biological fluctuation of erythrocyte FA composition is low, phospholipids account for almost all the lipid content of erythrocytes, and the FA profiles of erythrocytes represent those of tissues. Here, we elaborate on whether the status of maternal erythrocyte FAs can serve as a prognostic biomarker for reproductive health and fetomaternal complications, including embryonic and fetoplacental development, gestational length, and preeclampsia. In addition, factors with the potential of altering the maternal erythrocyte FAs such as maternal diet, lifestyle habits, genetics, and body composition are discussed.

FADS Polymorphisms Affect the Clinical and Biochemical Phenotypes of Metabolic Syndrome

Long-chain polyunsaturated fatty acids (LC-PUFAs) play important roles in human health, from controlling inflammation to lipid and glucose homeostasis. In our previous study, which employed a cluster analysis of a plasma fatty acid (FA) pattern, we identified two clusters of metabolic syndrome (MetS) independent of clinical and biochemical parameters within the whole study group (controls together with metabolic syndrome (MetS) patients). FA desaturase (FADS) genes are the key regulators of LC-PUFA metabolism. The aim of this study was to analyze associations between FADS polymorphisms and clusters of MetS. The study group consisted of 188 controls and 166 patients with MetS. The first cluster contained 71 controls (CON1) and 109 MetS patients (MetS1). The second cluster consisted of 117 controls (CON2) and 57 MetS patients (MetS2). In comparison with MetS2, cluster MetS1 displayed a more adverse risk profile. Cluster CON1 had, in comparison with CON2, higher body weight and increased triacylglycerol levels (p < 0.05). We found that the FADS rs174537 (p < 0.001), rs174570 (p < 0.01), and rs174602 (p < 0.05) polymorphisms along with two inferred haplotypes had statistically significant genotype associations with the splitting of MetS into MetS1 and MetS2. Conversely, we observed no significant differences in the distribution of FADS polymorphisms between MetS and CON subjects, or between CON1 and CON2. These associations between FADS polymorphisms and two clusters of MetS (differing in waist circumference, HOMA-IR, lipolysis, and oxidative stress) implicate the important influence of genetic factors on the phenotypic manifestation of MetS.

Influence of the nutritional status and oxidative stress in the desaturation and elongation of n-3 and n-6 polyunsaturated fatty acids: Impact on non-alcoholic fatty liver disease

Polyunsaturated fatty acids (PUFA) play essential roles in cell membrane structure and physiological processes including signal transduction, cellular metabolism and tissue homeostasis to combat diseases. PUFA are either consumed from food or synthesized by enzymatic desaturation, elongation and peroxisomal β-oxidation. The nutritionally essential precursors α-linolenic acid (C18:3n-3; ALA) and linoleic acid (C18:2n-6; LA) are subjected to desaturation by Δ6D/Δ5D desaturases and elongation by elongases 2/5, enzymes that are induced by insulin and repressed by PUFA. Maintaining an optimally low n-6/n-3 PUFA ratio is linked to prevention of the development of several diseases, including nonalcoholic fatty liver disease (NAFLD) that is characterized by depletion of PUFA promoting hepatic steatosis and inflammation. In this context, supplementation with n-3 PUFA revealed significant lowering of hepatic steatosis in obese patients, whereas prevention of fatty liver by high-fat diet in mice is observed in n-3 PUFA and hydroxytyrosol co-administration. The aim of this work is to review the role of nutritional status and nutrient availability on markers of PUFA biosynthesis. In addition, the impact of oxidative stress developed as a result of NAFLD, a redox imbalance that may alter the expression and activity of the enzymes involved, and diminished n-3 PUFA levels by free-radical dependent peroxidation processes will be discussed.

Investigation of Maternal Diet and FADS1 Polymorphism Associated with Long-Chain Polyunsaturated Fatty Acid Compositions in Human Milk

Increasing the amount of long-chain polyunsaturated fatty acids (LCPUFA) in human milk is an important strategy for infant growth and development. We investigated the associations of LCPUFA compositions in human milk with maternal diet (especially fish and shellfish intake), with fatty acid Δ5 desaturase gene (FADS1) polymorphisms, and with gene-diet interactions. The present study was performed as part of an adjunct study of the Japan Environment and Children’s Study. The participants were 304 lactating females, who provided human milk 6−7 months after delivery. Fatty acids in human milk were analyzed by gas chromatography, and dietary surveys were conducted using a brief self-administered diet history questionnaire. We also analyzed a single nucleotide polymorphism of FADS1 (rs174547, T/C). There was a significant difference in arachidonic acid (ARA) composition in human milk among the genotype groups, and the values were decreasing in the order of TT > TC > CC. The concentrations of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were also different between TT and CC genotype, indicating a tendency for decreasing values in the same order. The composition of ARA showed significant gene−dietary interactions in multiple regression analysis, and the positive correlation between fish and shellfish intake and ARA composition in human milk was significant only in the CC genotype. Moreover, the factor most strongly associated with EPA and DHA composition in human milk was fish and shellfish intake. Therefore, it was suggested that increasing fish and shellfish intake in mothers may increase EPA and DHA composition in human milk, while increasing fish and shellfish intake in CC genotype mothers may lead to increased ARA composition in human milk.

Single nucleotide polymorphism of fatty acid desaturase gene and breast cancer risk in estrogen receptor subtype

BACKGROUND

Breast cancer (BC) is the most common cancer of women and the second most common cancer overall globally. Data suggest that the plasma concentration of omega fatty acids (n-3 and n-6) and the impact of the genetic variant are associated with diet-related inflammatory disease, BC. This study was aimed to find an association between genetic variant rs174537 of fatty acid desaturase gene 1(FADS 1) and breast cancer estrogen receptor subtype.

METHODOLOGY

Hundred and two blood samples from women were quantified for fatty acids by gas chromatography. SNP rs 174537(G > T) showed maximum variability and the strongest genetic determinant in the Genome-wide association study were genotyped using Sanger sequencing.

RESULTS

The highest tertile of ALA showed a significantly reduced risk of BC compared to the lowest tertile (OR = 0.2, 95 %CL = 0.1-1.14, P = 0.03). Median values of ALA were higher in GT/TT genotype in ER +ve molecular subtype (P = 0.03) and DPA was higher in GG genotype of ER-ve molecular subtype (P = 0.037). When both the groups were put together the highest tertile of GG tertile showed significantly reduced risk of BC compared with the other lowest tertiles of GG and GT/TT genotypes (OR, 95% CL = 0.45(0.2-0.9).

CONCLUSION

The high levels of arachidonic acid and low levels of n-3 fatty acids result in a pro-inflammatory milieu and that these pro-inflammatory effects might contribute to BC. We conclude that the individuals with genetically determined lower activity of FADS1(minor allele T) will derive greater advantage from n-3 FAs than those with higher FADS1 activity (G allele) and reduce the BC risk.

Changes in Human Milk Fat Globule Composition Throughout Lactation: A Review

There has been a growing interest in understanding how the relative levels of human milk fat globule (MFG) components change over the course of lactation, how they differ between populations, and implications of these changes for the health of the infant. In this article, we describe studies published over the last 30 years which have investigated components of the MFG in term milk, focusing on changes over the course of lactation and highlighting infant and maternal factors that may influence these changes. We then consider how the potential health benefits of some of the milk fat globule membrane (MFGM) components and derived ingredients relate to compositional and functional aspects and how these change throughout lactation. The results show that the concentrations of phospholipids, gangliosides, cholesterol, fatty acids and proteins vary throughout lactation, and such changes are likely to reflect the changing requirements of the growing infant. There is a lack of consistent trends for changes in phospholipids and gangliosides across lactation which may reflect different methodological approaches. Other factors such as maternal diet and geographical location have been shown to influence human MFGM composition. The majority of research on the health benefits of MFGM have been conducted using MFGM ingredients derived from bovine milk, and using animal models which have clearly demonstrated the role of the MFGM in supporting cognitive and immune health of infants at different stages of growth and development.

Neurodevelopment, nutrition and genetics. A contemporary retrospective on neurocognitive health on the occasion of the 100th anniversary of the National Institute of Nutrition, Hyderabad, India

In celebration of the centenary of the National Institute of Nutrition (NIN), Hyderabad, India (1918-2018), a symposium highlighted the progress in nutrition knowledge made over the century, as well as major gaps in implementation of that knowledge. Brain famine caused by a shortage of nutrients required for perinatal brain development has unfortunately become a global reality, even as protein-calorie famine was largely averted by the development of high yield crops. While malnutrition remains widespread, the neglect of global food policies that support brain development and maintenance are most alarming. Brain disorders now top the list of the global burden of disease, even with obesity rising throughout the world. Neurocognitive health, remarkably, is seldom listed among the non-communicable diseases (NCDs) and is therefore seldom considered as a component of food policy. Most notably, the health of mothers before conception and through pregnancy as mediated by proper nutrition has been neglected by the current focus on early death in non-neurocognitive NCDs, thereby compromising intellectual development of the ensuing generations. Foods with balanced essential fatty acids and ample absorbable micronutrients are plentiful for populations with access to shore-based foods, but deficient only a few kilometres away from the sea. Sustained access to brain supportive foods is a priority for India and throughout the world to enable each child to develop to their intellectual potential, and support a prosperous, just, and peaceful world. Nutrition education and food policy should place the nutritional requirements for the brain on top of the list of priorities.

Plasma Oxylipin Profile Discriminates Ethnicities in Subjects with Non-Alcoholic Steatohepatitis: An Exploratory Analysis

Non-alcoholic fatty liver disease (NAFLD) is a common liver pathology that includes steatosis, or non-alcoholic fatty liver (NAFL), and non-alcoholic steatohepatitis (NASH). Without a clear pathophysiological mechanism, it affects Hispanics disproportionately compared to other ethnicities. Polyunsaturated fatty acids (PUFAs) and inflammatory lipid mediators including oxylipin (OXL) and endocannabinoid (eCB) are altered in NAFLD and thought to contribute to its pathogenesis. However, the existence of ethnicity-related differences is not clear. We employed targeted lipidomic profiling for plasma PUFAs, non-esterified OXLs and eCBs in White Hispanics (HIS, n = 10) and Caucasians (CAU, n = 8) with biopsy-confirmed NAFL, compared with healthy control subjects (HC; n = 14 HIS; n = 8 CAU). NAFLD was associated with diminished long chain PUFA in HIS, independent of histological severity. Differences in plasma OXLs and eCBs characterized ethnicities in NASH, with lower arachidonic acid derived OXLs observed in HIS. The secondary analysis comparing ethnicities within NASH (n = 12 HIS; n = 17 CAU), confirms these ethnicity-related differences and suggests lower lipoxygenase(s) and higher soluble epoxide hydrolase(s) activities in HIS compared to CAU. While causes are not clear, these lipidomic differences might be with implications for NAFLD severity and are worth further investigation. We provide preliminary data indicating ethnicity-specific lipidomic signature characterizes NASH which requires further validation.

Interpreting Clinical Trials With Omega-3 Supplements in the Context of Ancestry and FADS Genetic Variation

Human diets in developed countries such as the US have changed dramatically over the past 75 years, leading to increased obesity, inflammation, and cardiometabolic dysfunction. Evidence over the past decade indicates that the interaction of genetic variation with changes in the intake of 18-carbon essential dietary omega-6 (n-6) and omega-3 (n-3) polyunsaturated fatty acids (PUFA), linoleic acid (LA) and α-linolenic acid (ALA), respectively, has impacted numerous molecular and clinical phenotypes. Interactions are particularly relevant with the FADS1 and FADS2 genes, which encode key fatty acid desaturases in the pathway that converts LA and ALA to their long chain (≥20 carbons), highly unsaturated fatty acid (HUFA) counterparts. These gene by nutrient interactions affect the levels and balance of n-6 and n-3 HUFA that in turn are converted to a wide array of lipids with signaling roles, including eicosanoids, docosanoids, other oxylipins and endocannabinoids. With few exceptions, n-6 HUFA are precursors of pro-inflammatory/pro-thrombotic signaling lipids, and n-3 HUFA are generally anti-inflammatory/anti-thrombotic. We and others have demonstrated that African ancestry populations have much higher frequencies (vs. European-, Asian- or indigenous Americas-ancestry populations) of a FADS “derived” haplotype that is associated with the efficient conversion of high levels of dietary n-6 PUFA to pro-inflammatory n-6 HUFA. By contrast, an “ancestral” haplotype, carrying alleles associated with a limited capacity to synthesize HUFA, which can lead to n-3 HUFA deficiency, is found at high frequency in certain Hispanic populations and is nearly fixed in several indigenous populations from the Americas. Based on these observations, a focused secondary subgroup analysis of the VITAL n-3 HUFA supplementation trial stratifying the data based on self-reported ancestry revealed that African Americans may benefit from n-3 HUFA supplementation, and both ancestry and FADS variability should be factored into future clinical trials design.

Randomized controlled trial of early arachidonic acid and docosahexaenoic acid enteral supplementation in very preterm infants

OBJECTIVE

To evaluate changes in blood long-chain polyunsaturated fatty acid (LCPUFA) and oxylipin concentrations in very preterm infants from birth to 36 weeks' postmenstrual age (WPA) after providing an emulsified arachidonic acid (ARA):docosahexaenoic acid (DHA) supplement at two different concentrations.

STUDY DESIGN

This prospective, randomized trial assigned infants to receive a supplement (1) 80:40 group (80 mg/kg/day ARA and 40 mg/kg/day DHA, n = 9) or (2) 120:60 group (120 mg/kg/day ARA and 60 mg/kg/day DHA, n = 9). Infants received supplement daily from birth until 36 WPA. At baseline, 21 days of life and 36 WPA, the LCPUFAs were measured in plasma by gas chromatography/mass spectrophotometry. Additionally, LCPUFAs and oxylipins were analyzed in whole blood by ultra-high-performance liquid chromatography-tandem mass spectrometry. Furthermore, a sample of oral mucosa was obtained to analyze single-nucleotide polymorphism located in the FADS1 gene by PCR.

RESULTS

Gestational age was similar between groups (80:40 = 28⁺⁶ [27⁺³; 30⁺³] completed weeks^+days ; 120:60 = 29⁺⁶ [27⁺³; 30⁺⁵] completed weeks^+days , p = 0.83). At 36 WPA, the change in plasma ARA was significantly different between groups (80:40 group = 0.15 [-0.67; 0.69] %nmol, 120:60 = 1.68 [1.38; 3.16] %nmol, p = 0.031). In whole blood, the levels of ARA-derived oxylipins (5-, 8-, 9-, 11-, 15-HETE and 8,9-EET) and EPA-derived oxylipins (18-HEPE) significantly increase from baseline to 36 WPA in the 120:60 group than the 80:40 group.

CONCLUSION

Supplementation at high doses (120:60 mg/kg/day) increased levels of ARA, and EPA- and ARA-derived oxylipins compared to low doses (80:40 mg/kg/day). Differences were detected in EPA metabolites without a significant increase in plasma DHA.

Potential Role of Omega-3 Polyunsaturated Fatty Acids in Pediatric Food Allergy

Polyunsaturated fatty acids (PUFAs) are involved both in immune system regulation and inflammation. In particular, within the PUFAs category, omega-3 (ω-3) may reduce inflammation, whereas omega-6 (ω-6) PUFAs are generally considered to have a proinflammatory effect. Recent evidence highlights an imbalance in the ω-3:ω-6 ratio with an increased intake of ω-6, as a consequence of the shift towards a westernized diet. In critical age groups such as infants, toddlers and young children, as well as pregnant and lactating women or fish allergic patients, ω-3 intake may be inadequate. This review aims to discuss the potential beneficial effects of PUFAs on pediatric food allergy prevention and treatment, both at prenatal and postnatal ages. Data from preclinical studies with PUFAs supplementation show encouraging effects in suppressing allergic response. Clinical studies results are still conflicting about the best timing and dosages of supplementation and which individuals are most likely to benefit; therefore, it is still not possible to draw firm conclusions. With regard to food-allergic children, it is still debated whether PUFAs could slow disease progression or not, since consistent data are lacking. In conclusion, more data on the effects of ω-3 PUFAs supplementation alone or in combination with other nutrients are warranted, both in the general and food allergic population.

Genomic Insights Into the Genetic Structure and Natural Selection of Mongolians

Mongolians dwell at the Eastern Eurasian Steppe, where is the agriculture and pasture interlaced area, practice pastoral subsistence strategies for generations, and have their own complex genetic formation history. There is evidence that the eastward expansion of Western Steppe herders transformed the lifestyle of post-Bronze Age Mongolia Plateau populations and brought gene flow into the gene pool of Eastern Eurasians. Here, we reported genome-wide data for 42 individuals from the Inner Mongolia Autonomous Region of North China. We observed that our studied Mongolians were structured into three distinct genetic clusters possessing different genetic affinity with previous studied Inner Mongolians and Mongols and various Eastern and Western Eurasian ancestries: two subgroups harbored dominant Eastern Eurasian ancestry from Neolithic millet farmers of Yellow River Basin; another subgroup derived Eastern Eurasian ancestry primarily from Neolithic hunter-gatherers of North Asia. Besides, three-way/four-way qpAdm admixture models revealed that both north and southern Western Eurasian ancestry related to the Western Steppe herders and Iranian farmers contributed to the genetic materials into modern Mongolians. ALDER-based admixture coefficient and haplotype-based GLOBETROTTER demonstrated that the former western ancestry detected in modern Mongolian could be recently traced back to a historic period in accordance with the historical record about the westward expansion of the Mongol empire. Furthermore, the natural selection analysis of Mongolians showed that the Major Histocompatibility Complex (MHC) region underwent significantly positive selective sweeps. The functional genes, alcohol dehydrogenase (ADH) and lactase persistence (LCT), were not identified, while the higher/lower frequencies of derived mutations were strongly correlated with the genetic affinity to East Asian/Western Eurasian populations. Our attested complex population movement and admixture in the agriculture and pasture interlaced area played an important role in the formation of modern Mongolians.

Nutrigenetics and nutrigenomics-A personalized approach to nutrition

The prevalence of non-communicable diseases has been on an upward trajectory for some time and this puts an enormous burden on the healthcare expenditure. Lifestyle modifications including dietary interventions hold an immense promise to manage and prevent these diseases. Recent advances in genomic research provide evidence that focussing these efforts on individual variations in abilities to metabolize nutrients (nutrigenetics) and exploring the role of dietary compounds on gene expression (nutrigenomics and nutri-epigenomics) can lead to more meaningful personalized dietary strategies to promote optimal health. This chapter aims to provide examples on these gene-diet interactions at multiple levels to support the need of embedding targeted dietary interventions as a way forward to prevent, avoid and manage diseases.

Infant Metabolome in Relation to Prenatal DHA Supplementation and Maternal Single-Nucleotide Polymorphism rs174602: Secondary Analysis of a Randomized Controlled Trial in Mexico

BACKGROUND

Although DHA (22:6n-3) is critical for fetal development, results from randomized controlled trials (RCTs) of prenatal DHA supplementation report inconsistent effects on offspring health. Variants in fatty acid desaturase (FADS) genes that regulate the conversion of n-3 and n-6 essential fatty acids into their biologically active derivatives may explain this heterogeneity.

OBJECTIVES

We investigated the effect of prenatal DHA supplementation on the offspring metabolome at age 3 mo and explored differences by maternal FADS single-nucleotide polymorphism (SNP) rs174602.

METHODS

Data were obtained from a double-blind RCT in Mexico [POSGRAD (Prenatal Omega-3 Fatty Acid Supplementation and Child Growth and Development)] in which women (18-35 y old) received DHA (400 mg/d) or placebo from mid-gestation until delivery. Using high-resolution MS with LC, untargeted metabolomics was performed on 112 offspring plasma samples. Discriminatory metabolic features were selected via linear regression (P < 0.05) with false discovery rate (FDR) correction (q = 0.2). Interaction by SNP rs174602 was assessed using 2-factor ANOVA. Stratified analyses were performed, where the study population was grouped into carriers (TT, TC; n = 70) and noncarriers (CC; n = 42) of the minor allele. Pathway enrichment analysis was performed with Mummichog (P < 0.05).

RESULTS

After FDR correction, there were no differences in metabolic features between infants whose mothers received prenatal DHA (n = 58) and those whose mothers received placebo (n = 54). However, we identified 343 differentially expressed features in the interaction analysis after FDR correction. DHA supplementation positively enriched amino acid and aminosugars metabolism pathways and decreased fatty acid metabolism pathways among offspring of minor allele carriers and decreased metabolites within the tricarboxylic acid cycle and galactose metabolism pathways among offspring of noncarriers.

CONCLUSIONS

Our findings demonstrate differences in infant metabolism in response to prenatal DHA supplementation by maternal SNP rs174602 and further support the need to incorporate genetic analysis of FADS polymorphisms into DHA supplementation trials.This trial was registered at clinicaltrials.gov as NCT00646360.

Perinatal Polyunsaturated Fatty Acid Status and Obesity Risk

High obesity rates in almost all regions of the world prompt an urgent need for effective obesity prevention. Very good scientific evidence from cell culture and rodent studies show that the availability of essential polyunsaturated fatty acids (PUFA) and their long-chain polyunsaturated derivatives, namely, arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid, influence adipogenesis; for this reason, early life status may influence later obesity risk. The respective PUFA effects could be mediated via their eicosanoid derivatives, their influence on cell membrane properties, the browning of white adipose tissue, changes to the offspring gut microbiome, their influence on developing regulatory circuits, and gene expression during critical periods. Randomized clinical trials and observational studies show divergent findings in humans, with mostly null findings but also the positive and negative effects of an increased n-3 to n-6 PUFA ratio on BMI and fat mass development. Hence, animal study findings cannot be directly extrapolated to humans. Even though the mechanistic data basis for the effects of n-3 PUFA on obesity risk appears promising, no recommendations for humans can be derived at present.

Maternal FADS2 single nucleotide polymorphism modified the impact of prenatal docosahexaenoic acid (DHA) supplementation on child neurodevelopment at 5 years: Follow-up of a randomized clinical trial

BACKGROUND

Variability in the FADS2 gene, which codifies the Delta-6 Desaturases and modulates the conversion of essential n-3 and n-6 fatty acids into long-chain polyunsaturated fatty acids, might modify the impact of prenatal supplementation with n-3 docosahexaenoic acid (DHA) on neurodevelopment.

OBJECTIVE

To assess if maternal FADS2 single nucleotide polymorphisms (SNPs) modified the effect of prenatal DHA on offspring development at 5 years.

DESIGN

We conducted a post-hoc interaction analysis of the POSGRAD randomized controlled trial (NCT00646360) of prenatal supplementation with algal-DHA where 1094 pregnant women originally randomized to 400 mg/day of preformed algal DHA or a placebo from gestation week 18-22 through delivery. In this analysis, we included offspring with information on maternal genotype and neurodevelopment at 5 years (DHA = 316; Control = 306) and used generalized linear models to assess interactions between FADS2 SNPs rs174602 or rs174575 and prenatal DHA on neurodevelopment at 5 years measured with McCarthy Scales of Children's Abilities (MSCA).

RESULTS

Maternal and offspring characteristics were similar between groups. At baseline, mean (±standard deviation) maternal age was 26 ± 5 years and schooling was 12 ± 4 years. Forty-six percent (46%) of the children were female. Maternal minor allele frequencies were 0.37 and 0.33 for SNPs rs174602 and rs174575, respectively. There were significant variations by SNP rs174602 and intervention group (p for interactions <0.05) where children in the intervention group had higher MSCA scores on the quantitative (DHA: mean ± SEM = 22.6 ± 0.9 vs. Control = 19.1 ± 0.9, mean difference (Δ) = 3.45; p = 0.01) and memory (DHA = 27.9 ± 1.1 vs. Control = 23.7 ± 1.1, Δ = 4.26; p = 0.02) scales only among offspring of TT (minor allele homozygotes).

CONCLUSIONS

Maternal FADS2 SNP rs174602 modified the effect of prenatal DHA on cognitive development at 5 years. Variations in the genetic make-up of target populations could be an important factor to consider for prenatal DHA supplementation interventions.

The effects of a high eicosapentaenoic acid multinutrient supplement on measures of stress, anxiety and depression in young adults: Study protocol for NutriMOOD, a randomised double-blind placebo-controlled trial

Anxiety disorders affect nearly 20% of young adults aged 18-29 years. First-line treatment for anxiety disorders comprises pharmacotherapy and Cognitive Behavioural Therapy, options often criticised for their low efficacy and safety. In contrast, fish-oil-based supplements comprising omega-3 polyunsaturated fatty acids and supporting nutrients are gaining recognition as safe and effective alternatives. Here we present the protocol for a randomised, double-blind, placebo-controlled trial investigating the effects of a high eicosapentaenoic acid multinutrient supplement on validated measures of anxiety and depression in healthy university students experiencing non-clinical levels of anxiety and depression. The primary outcome is improvement in anxiety compared to the placebo group assessed via the Generalised Anxiety Disorder Assessment-7 scale. The participants will be randomised to active treatment comprising a daily dose of 1125 mg eicosapentaenoic acid, 441 mg docosahexaenoic acid, 330 mg magnesium and 7.5 mg vitamin E, or placebo, for 24 weeks, and will complete validated questionnaires and tablet-based tasks sensitive to mood at baseline and end of intervention. Circulating fatty acids and key biomarkers will also be assessed. The students will be genotyped for polymorphisms thought to influence the relationship between long-chain omega-3 polyunsaturated fatty acids and affect. Trial registration; ClinicalTrials.gov, NCT04844034.

Nutritional, Anthropometric and Sociodemographic Factors Affecting Fatty Acids Profile of Pregnant Women's Serum at Labour-Chemometric Studies

Diet influences the health of pregnant women and their children in prenatal, postnatal and adult periods. GC-FID fatty acids profile analysis in maternal serum and a survey of dietary habits were performed in 161 pregnant patients from the II Faculty and Clinic of Obstetrics and Gynaecology of the Medical University of Warsaw. Their diet did not fulfil all nutritional recommendations regarding dietary fat sources. Olive and rapeseed oil were the most popular edible oils. High usage of sunflower oil as well as high consumption of butter were also observed, whereas fish and fish oil intake by pregnant women was low. A chemometric approach for nutritional data, connected with anthropometric, sociodemographic and biochemical parameters regarding mothers and newborns, was conducted for diet and its impact estimation. It revealed four clusters of patients with differing fatty acids profile, which resulted from differences in their dietary habits. Multiparous women to a lesser extent followed dietary recommendations, which resulted in deterioration of fatty acids profile and higher frequency of complications. Observed high usage of sunflower oil is disquieting due to its lower oxidative stability, whereas high butter consumption is beneficial due to conjugated linoleic acids supply. Pregnant women should also be encouraged to introduce fish and fish oil into their diet, as these products are rich sources of long chain polyunsaturated fatty acids (LC PUFA). Multiparous women should be given special medical care by medical providers (physicians, midwifes and dietitians) and growing attention from the government to diminish the risk of possible adverse effects affecting mother and child.

Genome-Wide Association Study for Fatty Acid Composition in American Angus Cattle

Livestock is an important commodity playing a major role in the global economy. Red meat plays an important role in human life, as it is a good source of animal protein and energy. The fatty acid content of beef has been shown to impact the eating experience and nutritional value of beef. Therefore, this study aimed to identify genomic regions which can account for genetic variation in meat fatty acid content. Genotypes imputed to the Illumina BovineHD 770K BeadChip were used in this study. Thirty-six 1-Mb genomic regions with a posterior probability of inclusion (PPI) greater than 0.90 were identified to be associated with variation in the content of at least one fatty acid. The genomic regions (1Mb) which were associated with more than one fatty acid trait with high genetic variance and harbored good candidate genes were on Chromosome (Chr) 6 (fatty acid binding protein 2), Chr 19 (thyroid hormone receptor alpha, fatty acid synthase), Chr 26 (stearoyl-CoA desaturase), and Chr 29 (thyroid hormone responsive, fatty acid desaturase 2, and fatty acid desaturase 3). Further studies are required to identify the causal variants within the identified genomic regions. Findings from the present study will help to increase understanding of the variation in fatty acid content of beef and help to enhance selection for beef with improved fatty acid composition.

FADS1 gene polymorphism(s) and fatty acid composition of serum lipids in adolescents

Polyunsaturated fatty acids (PUFA) influence many physiological functions. Associations have been found between single nucleotide polymorphisms (SNP) in the FADS1 (Fatty acid desaturase 1) gene and the relative abundance of PUFA in serum lipids. This study examines the relationship between two SNPs in the FADS1 gene (rs174546, rs174537) and the fatty acid (FA) composition of serum lipids in adolescents (13-18 years). We used DNA samples (670 children; 336 girls and 334 boys) from the Childhood Obesity Prevalence and Treatment (COPAT) project. Genomic DNA was extracted from peripheral blood leukocytes in whole blood samples. For genotype analysis, TaqMan SNP Genotyping assays (Applied Biosystems) were used. Fatty acid composition of serum lipids was assessed using gas chromatography. The T-statistic and regression were used for statistical evaluations. Minor allele T carriers in both SNPs had significant lower level of palmitic acid (16:0, phospholipids) and arachidonic acid (20:4[n-6], phospholipids) in both sexes. In girls, we found a significant positive association between minor allele T carriers and eicosadienoic acid (20:2[n-6], cholesteryl esters) in both SNPs. Being a minor allele T carrier was significantly positively associated with dihomo-γ-linolenic acid (20:3[n-6], phospholipids) in boys in both SNPs. SNPs (including rs174546, rs174537) in the FADS gene cluster should have impacted desaturase activity, which may contribute to different efficiency of PUFA synthesis.

The Role of Resolvins, Protectins and Marensins in Non-Alcoholic Fatty Liver Disease (NAFLD)

Increased triacylglycerols' (TAG) synthesis, insulin resistance, and prolonged liver lipid storage might lead to the development of non-alcoholic fatty liver disease (NAFLD). Global prevalence of NAFLD has been estimated to be around 25%, with gradual elevation of this ratio along with the increased content of adipose tissue in a body. The initial stages of NAFLD may be reversible, but the exposition to pathological factors should be limited. As dietary factors greatly influence various disease development, scientists try to find dietary components, helping to alleviate the steatosis. These components include n-3 polyunsaturated (PUFA) fatty acids, especially eicosapentaenoic acid (EPA) and docosahexaenoic acids (DHA). This review focused on the role of resolvins, protectins and merensins in NAFLD.

Association between the Polymorphisms of fads2a and fads2b and Poly-Unsaturated Fatty Acids in Common Carp (Cyprinus carpio)

Simple Summary

Fishes are the major dietary source of polyunsaturated fatty acids (PUFAs) for humans. The limited availability of PUFAs derived from fish represents a critical bottleneck in food production systems, one that numerous research institutions and aqua-feed companies in this field are trying to overcome. This problem could be minimized by select-bred fish to be capable of more effectively producing endogenous PUFAs. Fatty acid desaturase 2 (fads2) is one of the rate-limiting enzymes in the synthesis of PUFAs. The common carp, one of the most important food and ornamental allo-tetraploid fish, encodes two fads2 genes (fads2a and fads2b). The PUFA contents among common carp individuals were numerous, suggesting that there might exist polymorphisms in fads2a and fads2b. However, selective breeding of common carp with high PUFA contents was hindered due to a lack of effective molecular markers. This study investigated the contents of PUFAs in common carp and identified polymorphisms in the CDS regions of fads2a and fads2b. The association study identified three cSNPs associated with the PUFA contents and suggested that fads2b might be the major gene responding for common carp PUFA contents. These cSNPs would be potential markers for future selection to improve the PUFA contents in common carp.

Abstract

Fatty acid desaturase 2 (fads2) is one of the rate-limiting enzymes in PUFAs biosynthesis. Compared with the diploid fish encoding one fads2, the allo-tetraploid common carp, one most important food fish, encodes two fads2 genes (fads2a and fads2b). The associations between the contents of different PUFAs and the polymorphisms of fads2a and fads2b have not been studied. The contents of 12 PUFAs in common carp individuals were measured, and the polymorphisms in the coding sequences of fads2a and fads2b were screened. We identified five coding single nucleotide polymorphisms (cSNPs) in fads2a and eleven cSNPs in fads2b. Using the mixed linear model and analysis of variance, a synonymous fads2a cSNP was significantly associated with the content of C20:3n-6. One non-synonymous fads2b cSNP (fads2b.751) and one synonymous fads2b cSNP (fads2b.1197) were associated with the contents of seven PUFAs and the contents of six PUFAs, respectively. The heterozygous genotypes in both loci were associated with higher contents than the homozygous genotypes. The fads2b.751 genotype explained more phenotype variation than the fads2b.1197 genotype. These two SNPs were distributed in one haplotype block and associated with the contents of five common PUFAs. These results suggested that fads2b might be the major gene responding to common carp PUFA contents and that fads.751 might be the main effect SNP. These cSNPs would be potential markers for future selection to improve the PUFA contents in common carp.

The evolutionary ecology of fatty-acid variation: Implications for consumer adaptation and diversification

The nutritional diversity of resources can affect the adaptive evolution of consumer metabolism and consumer diversification. The omega-3 long-chain polyunsaturated fatty acids eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) have a high potential to affect consumer fitness, through their widespread effects on reproduction, growth and survival. However, few studies consider the evolution of fatty acid metabolism within an ecological context. In this review, we first document the extensive diversity in both primary producer and consumer fatty acid distributions amongst major ecosystems, between habitats and amongst species within habitats. We highlight some of the key nutritional contrasts that can shape behavioural and/or metabolic adaptation in consumers, discussing how consumers can evolve in response to the spatial, seasonal and community-level variation of resource quality. We propose a hierarchical trait-based approach for studying the evolution of consumers' metabolic networks and review the evolutionary genetic mechanisms underpinning consumer adaptation to EPA and DHA distributions. In doing so, we consider how the metabolic traits of consumers are hierarchically structured, from cell membrane function to maternal investment, and have strongly environment-dependent expression. Finally, we conclude with an outlook on how studying the metabolic adaptation of consumers within the context of nutritional landscapes can open up new opportunities for understanding evolutionary diversification.

Ablation of fatty acid desaturase 2 (FADS2) exacerbates hepatic triacylglycerol and cholesterol accumulation in polyunsaturated fatty acid-depleted mice

Deficiency of polyunsaturated fatty acids (PUFAs) is known to induce hepatic steatosis. However, it is not clearly understood which type of PUFA is responsible for the worsening of steatosis. This study observed a marked accumulation of hepatic triacylglycerol and cholesterol in fatty acid desaturase 2 knockout (FADS2^-/- ) mice lacking both C18 and ≥ C20 PUFAs that were fed a PUFA-depleted diet. Hepatic triacylglycerol accumulation was associated with enhanced sterol regulatory element-binding protein (SREBP)-1-dependent lipogenesis and decreased triacylglycerol secretion into the plasma via very-low-density lipoprotein (VLDL). Furthermore, upregulation of cholesterol synthesis contributed to increased hepatic cholesterol content in FADS2^-/- mice. These results suggest that ≥ C20 PUFAs synthesized by FADS2 are important in regulating hepatic triacylglycerol and cholesterol accumulation during PUFA deficiency.