The health implications of changing linoleic acid intakes

Comprehensive evaluation of the chemical profile and antioxidant potential of buritirana (Mauritiella armata) an underexplored fruit from Brazilian Cerrado

Buritirana (Mauritella armata) is a fruit from a native Brazilian palm tree whose economic and industrial potential is still little explored. The nutritional composition and carbohydrates; organic acids; fatty acids; triacylglycerol; and phenolics profile of buritirana pulp, shells, and seeds were performed in this study. In addition, pH, color, ant total carotenoid, phenolic, flavonoids, flavonols, tannins, and antioxidant potential (ABTS, DPPH, ILP, FRAP, CUPRAC, and TRC) were determined in these parts of the fruit. The results indicated high lipid content and energy value for pulp (30.53 g 100 g-1, and 351.21 kcal 100 g-1, respectively) and shells (18.41 g 100 g-1, and 276.73 kcal 100 g-1, respectively). On the other hand, high fiber (63.09 g 100 g-1), starch (2.66 g 100 g-1), and carbohydrates (28.60 g 100 g-1) contents were observed for the seeds. Glucose was the main carbohydrate found in pulp and seed, while sucrose was the main sugar in shells. Tartaric acid was the predominant organic acid in pulp and shells (16.60 and 10.96 mg 100 g-1, respectively), while malic acid was the main organic acid in seeds (58.78 mg 100 g-1). Oleic and palmitic acid were the main fatty acids detected in buritirana pulp, shells, and seeds. Buritirana pulp and shells showed a high content of total phenolic and total flavonoid (918.58 and 940.63 mg GAE 100 g-1; and 679.31 and 444.94 mg CE 100 g-1, respectively). Moreover, a high antioxidant potential (DPPH•, CUPRAC, and ILP) was observed in the extracts obtained from pulp and shells. The pulp showed a significant content of carotenoids (270.23 μg g-1). Among the 28 phenolic compounds determined in buritirana pulp and seeds, and 27 in shells, 22 (pulp and seeds), and 21 (shells) were reported by first time in the literature. Ferulic acid in pulp and shells (99.39 and 111.69 μg g-1) and pinocembrin in seeds (19.21 μg g-1) were the main phenolic compounds identified in buritirana. Multivariate analysis showed high correlation of phenolic compounds on antioxidant potential. The results showed that buritirana is rich in nutrients and bioactive products and can be fully utilized. The products resulting from buritirana processing can be applied in the food, cosmetics, and pharmaceutical industries.

The re-emerging role of linoleic acid in paediatric asthma

Asthma is the most common chronic disease within the paediatric population. Although it is multifactorial, its onset may be linked to early-life exposures with subsequent impact on immune system development. Microbial and dietary metabolic products have been implicated in the development and exacerbation of paediatric asthma. Linoleic acid is the most common omega-6 polyunsaturated fatty acid in the Western diet. In this review, we summarise the literature regarding the involvement of linoleic acid in the development of and its impact on existing paediatric asthma. First, we summarise the existing knowledge surrounding the relationship between human microbial metabolism and allergic diseases in children. Next, we examine cellular or animal model-based mechanistic studies that investigated the impact of dietary- and microbial-derived linoleic acid metabolites on asthma. Finally, we review the literature investigating the impact of linoleic acid metabolites on the development and exacerbation of childhood asthma. While there is conflicting evidence, there is growing support for a role of linoleic acid in the onset and pathophysiology of asthma. We recommend that additional cellular, animal, and longitudinal studies are performed that target linoleic acid and its metabolites.

Non-esterified erythrocyte linoleic acid, arachidonic acid, and subjective sleep outcomes

OBJECTIVE

This study investigated whether non-esterified erythrocyte omega-6 PUFAs were associated with subjective assessment of sleep quality and duration, and risk for obstructive sleep apnea.

METHODS

In this secondary analysis of the cross-sectional OPPERA-II study, 538 adults completed the Pittsburgh Sleep Quality Index (PSQI), reported their usual hours of sleep, and answered STOP screening questions for obstructive sleep apnea. Circulating non-esterified erythrocyte concentrations of omega-6 PUFA linoleic acid and arachidonic acid were quantified by liquid chromatography tandem mass spectroscopy. Sleep outcomes were dichotomized as poor (PSQI ≤5) vs good (PSQI ≥6) sleep quality, insufficient or excessive (≤6 or >9 h) vs good (7-9 h) sleep duration, and high (≥2 affirmative responses) vs low (<2 affirmative responses) risk for obstructive sleep apnea. Non-esterified omega-6 PUFAs and the continuous covariates of body mass index, Short Form (SF) 12 Health Survey Physical and Mental Component scores and resting measures of systolic and diastolic blood pressure were standardized for multivariable analysis. Categorical covariates were study site, age, sex, and race/ethnicity. Multivariable-adjusted logistic regression first estimated odds ratios (OR) and 95% confidence limits (CL) for sleep outcomes using linoleic acid as the main exposure. Analysis was then repeated using arachidonic acid as the main exposure.

RESULTS

In the multivariable-adjusted model, each standard deviation increase in non-esterified erythrocyte linoleic acid was associated with higher odds of poor sleep quality (OR=1.2, 95% CL: 1.1, 1.5), insufficient or excessive sleep (OR= 1.3, 95% CL: 1.1, 1.6) and high-risk for obstructive sleep apnea (OR=1.3, 95% CL: 1.1, 1.6). Likewise, for each standard deviation increase in non-esterified erythrocyte arachidonic acid, odds increased of poor sleep quality (OR=1.2, 95% CL: 1.1, 1.5), and insufficient or excessive sleep (OR=1.2, 95% CL: 1.1, 1.5). Odds of being high risk for obstructive sleep apnea increased with greater circulating arachidonic acid, but the association did not reach statistical significance (OR=1.1, 95% CL: 0.9, 1.4).

CONCLUSION

Non-esterified erythrocyte linoleic acid and arachidonic acid were associated with poor sleep quality and insufficient or excessive sleep duration. Linoleic acid, but not arachidonic acid, was also associated with high risk for obstructive sleep apnea.

Antioxidative Role of Hygrophila erecta (Brum. F.) Hochr. on UV-Induced Photoaging of Dermal Fibroblasts and Melanoma Cells

Antioxidants are an important strategy for treating photoaging because excessive reactive oxygen species (ROS) are produced during UV irradiation. The therapeutic effects of methanol extracts of Hygrophila erecta (Brum. F.) Hochr. (MEH) against UV-induced photoaging were examined by monitoring the changes in the antioxidant defense system, apoptosis, extracellular matrix (ECM) modulation, inflammatory response, and melanin synthesis in normal human dermal fibroblast (NHDF) cells and melanoma B16F1 cells. Four bioactive compounds, including 4-methoxycinnamic acid, 4-methoxybenzoic acid, methyl linoleate, and asterriquinone C-1, were detected in MEH, while the DPPH free radical scavenging activity was IC₅₀ = 7.6769 µg/mL. UV-induced an increase in the intracellular ROS generation, NO concentration, SOD activity and expression, and Nrf2 expression were prevented with the MEH treatment. Significant decreases in the number of apoptotic cells, the ratio of Bax/Bcl-2, and cleaved Cas-3/Cas-3 were observed in MEH-treated NHDF cells. The MEH treatment induced the significant prevention of ECM disruption and suppressed the COX-2-induced iNOS mediated pathway, expression of inflammatory cytokines, and inflammasome activation. Finally, the expression of the melanin synthesis-involved genes and tyrosinase activity decreased significantly in the α-melanocyte-stimulating hormone (MSH)-stimulated B16F1 cells after the MEH treatment. MEH may have an antioxidative role against UV-induced photoaging by suppressing ROS-induced cellular damage.

Title: Involvement of unsaturated fatty acid biosynthesis in CRC progression based on in vitro and in silico studies

Obesity is one of the risk factors concerns of colorectal cancer (CRC), the most common type of gastrointestinal cancer, due to the changing lifestyle and especially diet. There are various molecular pathways associated with obesity and the risk of CRC incidence, such as insulin resistance or elevated plasma free fatty acids, which alter the signaling pathways of intestinal epithelial cells. The aim of this study was to better understand the significance of unsaturated fatty acid biosynthesis on pathogenesis of colon cancer in obese. Based on GSE20931 dataset, obese individuals affected by CRC had higher increased gene expression than non-obese individuals. The analysis showed that in obese individuals, the 16 signaling pathway genes were activated and increased (FDR <0.05) significantly. The biosynthetic pathway of unsaturated fatty acids showed a cross-talk with the arachidonic acid metabolism pathway and the PPAR signaling pathway is influenced and regulated via these pathways. The biosynthetic pathway of unsaturated fatty acids consisting of 22 genes, were analyzed using GEO data and revealed that 4 genes (HSD17B12, TECR, FADS2, ELOVL5) from this pathway were significantly increased (FDR <0.05). These data were validated based on TCGA data (Adj.p.value <0.001). The expression level of candidate genes in HT-29 cells decreased significantly (P.value <0.01), and PPARγ expression increased under linoleic acid treatment (200 μM) compared to control cells. Moreover, in presence of linoleic acid treatment, migration, colony formation, and proliferation decreased (P.value <0.01) in presence of treatment. In summary, the Biosynthesis pathway of unsaturated fatty acids is an interesting and critical pathway in CRC.

A plasma fatty acid profile associated to type 2 diabetes development: from the CORDIOPREV study

Purpose

The prevalence of type 2 diabetes mellitus (T2DM) is increasing worldwide. For this reason, it is essential to identify biomarkers for the early detection of T2DM risk and/or for a better prognosis of T2DM. We aimed to identify a plasma fatty acid (FA) profile associated with T2DM development.

Methods

We included 462 coronary heart disease patients from the CORDIOPREV study without T2DM at baseline. Of these, 107 patients developed T2DM according to the American Diabetes Association (ADA) diagnosis criteria after a median follow-up of 60 months. We performed a random classification of patients in a training set, used to build a FA Score, and a Validation set, in which we tested the FA Score.

Results

FA selection with the highest prediction power was performed by random survival forest in the Training set, which yielded 4 out of the 24 FA: myristic, petroselinic, α-linolenic and arachidonic acids. We built a FA Score with the selected FA and observed that patients with a higher score presented a greater risk of T2DM development, with an HR of 3.15 (95% CI 2.04–3.37) in the Training set, and an HR of 2.14 (95% CI 1.50–2.84) in the Validation set, per standard deviation (SD) increase. Moreover, patients with a higher FA Score presented lower insulin sensitivity and higher hepatic insulin resistance (p < 0.05).

Conclusion

Our results suggest that a detrimental FA plasma profile precedes the development of T2DM in patients with coronary heart disease, and that this FA profile can, therefore, be used as a predictive biomarker.

Clinical Trials.gov.Identifier

NCT00924937.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00394-021-02676-z.

Prepubertal Dietary and Plasma Phospholipid Fatty Acids Related to Puberty Timing: Longitudinal Cohort and Mendelian Randomization Analyses

Dietary intakes of polyunsaturated, monounsaturated and saturated fatty acids (FAs) have been inconsistently associated with puberty timing. We examined longitudinal associations of prepubertal dietary and plasma phospholipid FAs with several puberty timing traits in boys and girls. In the Avon Longitudinal Study of Parents and Children, prepubertal fat intakes at 3-7.5 years and plasma phospholipid FAs at 7.5 years were measured. Timings of Tanner stage 2 genital or breast development and voice breaking or menarche from repeated reports at 8-17 years, and age at peak height velocity (PHV) from repeated height measurements at 5-20 years were estimated. In linear regression models with adjustment for maternal and infant characteristics, dietary substitution of polyunsaturated FAs for saturated FAs, and higher concentrations of dihomo-γ-linolenic acid (20:3n6) and palmitoleic acid (16:1n7) were associated with earlier timing of puberty traits in girls (n = 3872) but not boys (n = 3654). In Mendelian Randomization models, higher genetically predicted circulating dihomo-γ-linolenic acid was associated with earlier menarche in girls. Based on repeated dietary intake data, objectively measured FAs and genetic causal inference, these findings suggest that dietary and endogenous metabolic pathways that increase plasma dihomo-γ-linolenic acid, an intermediate metabolite of n-6 polyunsaturated FAs, may promote earlier puberty timing in girls.

The Effects of Linoleic Acid Consumption on Lipid Risk Markers for Cardiovascular Disease in Healthy Individuals: A Review of Human Intervention Trials

Cardiovascular disease (CVD) is the leading cause of death worldwide. Risk factors for developing this disease include high serum concentrations of total cholesterol, triglycerides, low-density lipoproteins, very-low density lipoproteins, and low concentrations of high-density lipoproteins. One proposed dietary strategy for decreasing risk factors involves replacing a portion of dietary saturated fatty acids with mono- and polyunsaturated fatty acids (PUFAs). The essential omega-6 PUFA, linoleic acid (LA), is suggested to decrease the risk for CVD by affecting these lipid risk markers. Reviewing human intervention trials will provide further evidence of the effects of LA consumption on risk factors for CVD. PubMed was used to search for peer-reviewed articles. The purpose of this review was: (1) To summarize human intervention trials that studied the effects of LA consumption on lipid risk markers for CVD in healthy individuals, (2) to provide mechanistic details, and (3) to provide recommendations regarding the consumption of LA to decrease the lipid risk markers for CVD. The results from this review provided evidence that LA consumption decreases CVD lipid risk markers in healthy individuals.

Distribution of Free and Esterified Oxylipins in Cream, Cell, and Skim Fractions of Human Milk

Human milk contains oxylipins involved in infant development. Although oxylipins have been identified in whole or skim milk, their localization within human milk cream, cell, and skim fractions is not known. This study determined the distribution of free and esterified oxylipins in cream, cell, and skim fractions of human milk. Out of 72 oxylipins probed by mass-spectrometry, 42, 29, and 41 oxylipins (free or bound) were detected in cream, cell, and skim fractions, respectively. Over 90% of free and bound oxylipins were derived from linoleic acid in all milk fractions. Other oxylipins were derived from n-6 arachidonic acid and dihomo-gamma-linolenic acid, and n-3 alpha-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid. Free oxylipins were more abundant in skim milk (59.9% of total oxylipins) compared to cream and cell pellet, whereas esterified oxylipins were most abundant in milk cream and cell pellets (74.9-76.9%). The heterogenous distribution of oxylipins in different fractions of human milk may regulate the guided release of these bioactive signaling molecules within infants.

Chemical composition, antioxidant and antitumor activities of sub-fractions of wild and cultivated Pleurotus ferulae ethanol extracts

Pleurotus ferulae is an edible and medicinal mushroom with various bioactivities. Here, the ethanol extracts of wild and cultivated P. ferulae (PFEE-W and PFEE-C) and their subfractions including petroleum ether (Pe-W/Pe-C), ethyl acetate (Ea-W/Ea-C) and n-butanol (Ba-W/Ba-C) were prepared to evaluate their antioxidant and antitumor activities. Both PFEE-W and PFEE-C show the antioxidant activity and PFEE-W is stronger than PFEE-C. The antioxidant activities of their subfractions are in the following order: Ea > Ba > Pe. Moreover, PFEE-W and PFEE-C significantly inhibit the proliferation of murine melanoma B16 cells, human esophageal cancer Eca-109 cells, human gastric cancer BGC823 cells and human cervical cancer HeLa cells through induction of apoptosis, which partially mediated by reactive oxygen species. The antitumor activities of their subfractions are in the following order: Ea ≥ Pe > Ba. Pe-W shows higher antitumor activity compared with Pe-C, which might be correlated with the difference of their components identified by gas chromatography-mass spectrometry. These results suggest that both wild and cultivated P. ferulae have antioxidant and antitumor activities, and cultivated P. ferulae could be used to replace wild one in some functions.

The Mulberry (Morus alba L.) Fruit-A Review of Characteristic Components and Health Benefits

Mulberry (Morus alba L.) fruit has a high yield in one fruiting season in many countries, especially in Asia, and a long history of use as an edible fruit and traditional medicine. A great diversity of nutritive compounds such as fatty acids, amino acids, vitamins, minerals, and bioactive compounds, including anthocyanins, rutin, quercetin, chlorogenic acid, and polysaccharides have been found in mulberry fruit depending on the cultivars and maturity stages. Furthermore, the extracts and active components of mulberry fruit have demonstrated numerous biological activities, including antioxidant, neuroprotective, antiatherosclerosis, immunomodulative, antitumor, antihyperglycemic, and hypolipidemic activities in in vitro and in vivo studies, and they have received increasing interest from researchers and pharmaceutical companies. Although some mechanistic studies further substantiate these potential health benefits of mulberry fruit, a need exists to make a better understanding of the roles of these compounds in traditional medicine and the diet. This review provides recent findings regarding the chemical constituents and biological activities of mulberry fruit, which may be useful for stimulating deep research of mulberry fruit and for predicting their uses as important and safe contributors to benefit human health.

Effects of eicosapentaenoic acid and docosahexaenoic acid on anxiety-like behavior in socially isolated rats

The effects of fish oil for improving mental health have been reported. The present study was undertaken to compare the effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on anxiety-like behavior using a rat model. Experimental diets enriched in EPA or DHA as glycerides were prepared. Rats were exposed to social isolation stress and fed the experimental diet for 14 days. The results of behavioral tests revealed that rats fed the EPA-enriched diet exhibited less anxiety-like behavior than rats fed the control or DHA-enriched diets. Furthermore, EPA suppressed anxiety-like behavior only in socially isolated rats. The increase in EPA contents in the brain phospholipid fraction by feeding EPA-enriched diet was more significant than that of DHA by feeding DHA-enriched diet. These results suggest that dietary EPA is more anxiolytic than DHA in rats exposed to social isolation stress and is effective in increasing EPA content in brain membranes.

Serum polyunsaturated fatty acids and risk of psychiatric disorder after acute coronary syndrome: A prospective cohort study

BACKGROUND

Around 20% of patients with acute coronary syndrome (ACS) develop depression. Furthermore, some observational studies revealed baseline polyunsaturated fatty acids (PUFAs) may affect the prognosis of depression after ACS. This prospective cohort study examined the association between psychiatric disorder and PUFAs after ACS.

METHODS

Subjects were ACS patients admitted to a Tokyo teaching hospital. Psychiatric morbidity as a primary endpoint was measured using structured interview 3 months after admission. At admission, serum n-3 and n-6 PUFAs were measured by gas chromatography and patients were interviewed to evaluate medical information. Multiple logistic regression analysis was performed to calculate odds ratios (ORs) and 95% confidence intervals to examine the association between PUFAs at baseline and psychiatric disorder after ACS.

RESULTS

Between March 2014 and August 2016, 100 patients completed the follow-up assessment. Eleven patients (11%) showed some form of new-onset psychiatric disorder at 3 months, mainly depressive episode (major, 5; minor, 1) and PTSD (full, 1; partial, 2). Psychiatric disorder was predicted by serum linoleic acid level (OR=3.96) and Hospital Anxiety and Depression Scale total score (OR=1.34) at baseline. No significant associations were seen with other PUFAs.

LIMITATIONS

The results were obtained from a single hospital and based on a small number of participants. There might be some patients with new-onset psychiatric disorder among the refused patients.

CONCLUSIONS

Psychiatric disorder incidence in ACS patients might be lower in Japan than in Western countries. Reduced intake of linoleic acid-containing foods might prevent depression or PTSD after ACS.

Effect of DHA supplementation on oxylipin levels in plasma and immune cell stimulated blood

INTRODUCTION

EPA and DHA cause different physiological effects, which are in many cases mediated via their oxidative metabolites (oxylipins). However, metabolism studies investigating the effect of either EPA or DHA on comprehensive oxylipin patterns are lacking.

MATERIAL AND METHODS

The short and long term (1, 3, 6, and 12 week) effect of 1076mg/d DHA (free of EPA) on free (unesterified) oxylipin concentrations in plasma and lipopolysacharid (LPS) stimulated blood of 12 healthy men (mean age 25.1 ± 1.5 years) was investigated.

RESULTS

After DHA supplementation, plasma levels of all DHA-oxylipins (HDHAs, EpDPEs, DiHDPEs) significantly increased (up to 600%) in a time-dependent fashion. Oxylipins of EPA and arachidonic acid (AA) were also affected. Whereas a slight increase in several EPA-derived hydroxy-FAs (including the RvE1 precursor 18-HEPE) and dihydroxy-FAs was observed after DHA supplementation, a trend to a slight decline in AA-derived oxylipin levels was found. In LPS stimulated blood, it is shown that DHA supplementation significantly reduces the ability of immune cells to form AA-derived COX (TXB2 and PGB2) and 12-LOX (12-HETE) eicosanoids. While no increase in EPA COX metabolites was found, n-3 PUFA 12-LOX metabolites of EPA (12-HEPE) and DHA (14-HDHA) were highly induced.

CONCLUSION

We demonstrated that DHA supplementation causes a time-dependent shift in the entire oxylipin profile suggesting a cross-linked metabolism of PUFAs and subsequent formation of oxygenated lipid mediators.

Effects of docosahexaenoic acid supplementation on PUFA levels in red blood cells and plasma

INTRODUCTION

Polyunsaturated fatty acids (PUFA) are metabolized in a complex network of elongation, desaturation and beta oxidation.

MATERIAL AND METHODS

The short (1 and 3 wk), and long term (6 and 12 wk) effect of 1076mg/d docosahexaenoic acid (DHA, free of eicosapentaenoic acid (EPA)) on (absolute) PUFA concentrations in plasma and red blood cells (RBC) of 12 healthy men (mean age 25.1±1.5 years) was investigated.

RESULTS

RBC DHA concentrations significantly (p<0.001) increased from 28±1.6µg/mL to 38±2.0µg/mL (wk 1), 52±3.3µg/mL (wk 3), 68±2.6µg/mL (wk 6), and 79±3.5µg/mL (wk 12). Arachidonic acid (AA) concentrations declined in response to DHA treatment, while the effect was more pronounced in plasma (wk 0: 183±9.9µg/mL, wk 12: 139±8.0µg/mL, -24%, p<0.001) compared to RBC (wk 0: 130±3.7µg/mL, wk 12: 108±4.0µg/mL, -16%, p=0.001). Furthermore, an increase of EPA concentrations in plasma (wk 0: 15±1.5µg/mL, wk 1:19±1.6µg/mL, wk 3: 27±2.3µg/mL, wk 6: 23±1.2µg/mL, wk 12: 25±1.7µg/mL, p<0.001) and RBC (wk 0: 4.7±0.33µg/mL, wk 1: 6.7±1.3µg/mL, wk 3: 8.0±0.66µg/mL, wk 6: 6.9±0.44µg/mL, wk 12: 6.7±0.45µg/mL, n.s.) was observed suggesting a retroconversion of DHA to EPA.

CONCLUSION

Based on PUFA concentrations we showed that DHA supplementation results in increased EPA levels, whereas it is not known if this impacts the formation of EPA-derived lipid mediators. Furthermore, shifts in the entire PUFA pattern after supplementation of EPA or DHA should be taken into account when discussing differential physiological effects of EPA and DHA.

Lipid production by yeasts grown on crude glycerol from biodiesel industry

The main carbon source used for growth by four yeast strains (Yarrowia lipolytica CCMA 0357, Y. lipolytica CCMA 0242, Wickerhamomyces anomalus CCMA 0358, and Cryptococcus humicola CCMA 0346) and their lipid production were evaluated, using different concentrations of crude and pure glycerol and glucose. Whereas crude glycerol (100 g/L) was the main carbon source used by Y. lipolytica CCMA 0357 (nearly 15 g/L consumed at 120 hr) and W. anomalus CCMA 0358 (nearly 45.10 g/L consumed at 48 hr), pure glycerol (150 g/L) was the main one used by C. humicola CCMA 0346 (nearly 130 g/L consumed). On the other hand, Y. lipolytica CCMA 0242 used glucose (100 g/L) as its main source of carbon (nearly 96.48 g/L consumed). Y. lipolytica CCMA 0357 demonstrated the highest lipid production [about 70% (wt/wt)], forming palmitic (45.73% of fatty acid composition), stearic (16.43%), palmitoleic (13.29%), linolenic (10.77%), heptadecanoic (4.07%), and linoleic (14.14%) acids. Linoleic acid, an essential fatty acid, was produced by all four yeast strains but in varying degrees, representing 70.42% of the fatty acid profile of lipids produced by C. humicola CCMA 0346.

Association of Plasma Phospholipid n-3 and n-6 Polyunsaturated Fatty Acids with Type 2 Diabetes: The EPIC-InterAct Case-Cohort Study

BACKGROUND

Whether and how n-3 and n-6 polyunsaturated fatty acids (PUFAs) are related to type 2 diabetes (T2D) is debated. Objectively measured plasma PUFAs can help to clarify these associations.

METHODS AND FINDINGS

Plasma phospholipid PUFAs were measured by gas chromatography among 12,132 incident T2D cases and 15,919 subcohort participants in the European Prospective Investigation into Cancer and Nutrition (EPIC)-InterAct study across eight European countries. Country-specific hazard ratios (HRs) were estimated using Prentice-weighted Cox regression and pooled by random-effects meta-analysis. We also systematically reviewed published prospective studies on circulating PUFAs and T2D risk and pooled the quantitative evidence for comparison with results from EPIC-InterAct. In EPIC-InterAct, among long-chain n-3 PUFAs, α-linolenic acid (ALA) was inversely associated with T2D (HR per standard deviation [SD] 0.93; 95% CI 0.88-0.98), but eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were not significantly associated. Among n-6 PUFAs, linoleic acid (LA) (0.80; 95% CI 0.77-0.83) and eicosadienoic acid (EDA) (0.89; 95% CI 0.85-0.94) were inversely related, and arachidonic acid (AA) was not significantly associated, while significant positive associations were observed with γ-linolenic acid (GLA), dihomo-GLA, docosatetraenoic acid (DTA), and docosapentaenoic acid (n6-DPA), with HRs between 1.13 to 1.46 per SD. These findings from EPIC-InterAct were broadly similar to comparative findings from summary estimates from up to nine studies including between 71 to 2,499 T2D cases. Limitations included potential residual confounding and the inability to distinguish between dietary and metabolic influences on plasma phospholipid PUFAs.

CONCLUSIONS

These large-scale findings suggest an important inverse association of circulating plant-origin n-3 PUFA (ALA) but no convincing association of marine-derived n3 PUFAs (EPA and DHA) with T2D. Moreover, they highlight that the most abundant n6-PUFA (LA) is inversely associated with T2D. The detection of associations with previously less well-investigated PUFAs points to the importance of considering individual fatty acids rather than focusing on fatty acid class.

Low Dietary c9t11-Conjugated Linoleic Acid Intake from Dairy Fat or Supplements Reduces Inflammation in Collagen-Induced Arthritis

Dietary cis-9,trans-11 (c9t11) conjugated linoleic acid (CLA) fed at 0.5 % w/w was previously shown to attenuate inflammation in the murine collagen-induced (CA) arthritis model, and growing evidence implicates c9t11-CLA as a major anti-inflammatory component of dairy fat. To understand c9t11-CLA's contribution to dairy fat's anti-inflammatory action, the minimum amount of dietary c9t11-CLA needed to reduce inflammation must be determined. This study had two objectives: (1) determine the minimum dietary anti-inflammatory c9t11-CLA intake level in the CA model, and (2) compare this to anti-inflammatory effects of dairy fat (non-enriched, naturally c9t11-CLA-enriched, or c9t11-CLA-supplemented). Mice received the following dietary fat treatments (w/w) post arthritis onset: corn oil (6 % CO), 0.125, 0.25, 0.375, and 0.5 % c9t11-CLA, control butter (6 % CB), c9t11-enriched butter (6 % EB), or c9t11-CLA-supplemented butter (6 % SB, containing 0.2 % c9t11-CLA). Paw arthritic severity and pad swelling were scored and measured, respectively, over an 84-day study period. All c9t11-CLA and butter diets decreased the arthritic score (25-51 %, P < 0.01) and paw swelling (8-11 %, P < 0.01). Throughout the study, plasma tumor necrosis factor (TNFα) was elevated in CO-fed arthritic mice compared to non-arthritic (NA) mice but was reduced in 0.5 % c9t11-CLA- and EB-fed mice. Interleukin-1β and IL-6 were increased in arthritic CO-fed mice compared to NA mice but were reduced in 0.5 % c9t11-CLA- and EB-fed mice through day 42. In conclusion, 0.125 % c9t11-CLA reduced clinical arthritis as effectively as higher doses, and decreased arthritis in CB-fed mice suggested that the minimal anti-inflammatory levels of c9t11-CLA might be below 0.125 %.

Excessive dietary linoleic acid induces proinflammatory markers in rats

Following the historical dietary recommendations, the substitution of polyunsaturated fatty acids (PUFAs) for saturated fatty acids (SFAs) resulted in a dramatic increase of linoleic acid (LA) in the Western diet. While proatherogenic properties of SFAs have been described, the involvement of LA on the inflammatory process remains controversial. Herein, we evaluated the effects of an excessive LA intake on the cytokine-induced expression of endothelial adhesion molecules vascular cell adhesion molecule-1 (VCAM-1) and intercellular cell adhesion molecule-1 (ICAM-1), through the nuclear factor (NF)-κB pathway, in comparison with a control diet and regarding a "positive" SFA diet. Wistar rats were fed experimental diets - a control diet or diets enriched with LA or SFA - for 11 weeks. Plasma lipid parameters and proinflammatory cytokine production such as interleukin-1β and tumor necrosis factor (TNF)-α were analyzed. Expression of endothelial adhesion molecules and NF-κB was determined by immunohistochemical analysis. No difference was observed in body weight. The enriched diets did not affect triglyceride and total cholesterol levels in plasma. Our results demonstrated that excessive dietary LA intake increased TNF-α levels (P<.05) in plasma. Rats fed the LA-enriched diet showed a significantly higher expression of VCAM-1, ICAM-1 and NF-κB in aortas. In addition, our results demonstrated that an excess of LA is more efficient to activate endothelial molecular process than an excess of SFA. The present study provides further support for the proinflammatory properties of LA and suggests an LA-derivatives pathway involved in the inflammatory process.

Consumption of a high n-3 polyunsaturated fatty acid diet during gradual mild physiological stress in rats

n-3 Polyunsaturated fatty acids (n-3PUFAs) may be beneficial for anxiety and depression under stressful conditions. Studies however, typically utilise physical or sudden physiological stress, while gradual physiological stress is also relevant to human conditions. Using deoxycorticosterone acetate (DOCA) administration to induce gradual physiological stress, this study investigated the impact of n-3PUFAs under gradual physiological stress in rats. Animals (aged 2 months) (N=8-12/group) received daily injections of DOCA or vehicle and were concurrently fed a high n-3PUFA or control diet for eight weeks. Behavioural measures were taken throughout. Behavioural tests and physiological measures were conducted after six and eight weeks respectively. DOCA administration decreased plasma renin, plasma proteins and relative adrenal weight, and increased water intake, relative kidney weight, and anxiety in the open field. These findings demonstrate disruptions to the renin-angiotensin-aldosterone system, a result of mild physiological stress, that also impact on anxiety behaviours. No effects of n-3PUFAs were found.

Dietary linoleic acid requirements in the presence of α-linolenic acid are lower than the historical 2 % of energy intake value, study in rats

Previous studies on rats and human subjects have established that the linoleic acid (LA) requirement is 2 % of the total energy intake (en%), but is obtained in the absence of α-linolenic acid (ALA) and consequently appear to be overestimated. This raises questions since a recent study including ALA has suggested to divide the historical value by four. However, this recent study has remained inconclusive because the animals used were not totally LA-deficient animals. For the first time, the present study was especially designed using physiological and biochemical markers and performed in two steps: (1) to achieve a specific n-6 fatty acid deficiency model using growing male rats fed either a 0 en% from LA/0 en% from ALA (0LA/0ALA), 0LA/0·5ALA or 2LA/0·5ALA diet, born from female rats fed a 0LA/0·5ALA diet; and (2) to refine the required level of LA in the presence of ALA using rats fed either a 0LA/0ALA, 0·5LA/0·5ALA, 1LA/0·5ALA, 1·5LA/0·5ALA diet, born from female rats fed a 0LA/0·5ALA diet. The first step shows that the best LA deficiency model was obtained using rats fed the 0LA/0ALA diet, born from female rats fed the 0LA/0·5ALA diet. The second step demonstrates that in growing rats, LA deficiency was corrected with an intake of 1-1·5 en% from LA and 0·5 en% from ALA. These data suggest that the requirements in humans should be revisited, considering the presence of ALA to set up the recommendation for LA.

Bioactivity and phytochemical characterization of Arenaria montana L

An aqueous extract ofA. montanamay be used as a functional food due to the high antioxidant and cytotoxic activities, and due to the presence of bioactive compounds.

Differential effects of adulterated versus unadulterated forms of linoleic acid on cardiovascular health

According to the classic "diet-heart" hypothesis, high dietary intake of saturated fats and cholesterol combined with low intake of polyunsaturated fats can increase levels of serum cholesterol and lead to the development of atherogenic plaques and ultimately cardiovascular diseases. Recently, the beneficial health effects of omega-6 polyunsaturated fatty acids, particularly linoleic acid (LA), on cardiovascular health have been called into question with some scientists suggesting that consumption of LA should be reduced in Western countries. The focus of this critical review is on the controversy surrounding the effects of dietary intake of LA on cardiovascular health. Specifically, we critically examined the effects of both unadulterated and adulterated forms of LA on cardiovascular health outcomes based on findings from epidemiological studies and randomized controlled trials. Additionally, we address common concerns surrounding dietary intake of LA regarding its relationship with arachidonic acid, the ratio of omega-6 to omega-3 fatty acids, and its relationship with inflammation. Our critical review indicates that unadulterated forms of LA are cardioprotective and should be consumed as part of a healthy diet. In contrast, abundant evidence now indicates that adulterated forms of LA, predominantly hydrogenated vegetable oils, are atherogenic and should not be considered part of a healthy diet. The ability to adulterate the natural omega-6 fatty acid, LA, has contributed to mixed findings regarding the effects of this fatty acid on cardiovascular health. Thus, it is critical that the source of LA be taken into account when drawing conclusions about the physiological effects of this fatty acid. The findings of the present review are in line with current dietary recommendations of the American Heart Association.

Linoleic acid: between doubts and certainties

Linoleic acid is the most abundant polyunsaturated fatty acid in human nutrition and represents about 14 g per day in the US diet. Following the discovery of its essential functions in animals and humans in the early 1920's, studies are currently questioning the real requirement of linoleic acid. It seems now overestimated and creates controversy: how much linoleic acid should be consumed in a healthy diet? Beyond the necessity to redefine the dietary requirement of linoleic acid, many questions concerning the consequences of its excessive consumption on human health arise. Linoleic acid is a direct precursor of the bioactive oxidized linoleic acid metabolites. It is also a precursor of arachidonic acid, which produces pro-inflammatory eicosanoids and endocannabinoids. A majority of the studies on linoleic acid and its derivatives show a direct/indirect link with inflammation and metabolic diseases. Many authors claim that a high linoleic acid intake may promote inflammation in humans. This review tries to (i) highlight the importance of reconsidering the actual requirement of linoleic acid (ii) point out the lack of knowledge between dietary levels of linoleic acid and the molecular mechanisms explaining its physiological roles (iii) demonstrate the relevance of carrying out further human studies on the single variable linoleic acid.

Comparison of free serum oxylipin concentrations in hyper- vs. normolipidemic men

Oxylipins, the oxidation products of unsaturated fatty acids (FA), are potent endogenous mediators being involved in the regulation of various biological processes such as inflammation, pain and blood coagulation. Compared to oxylipins derived from arachidonic acid (AA) by cyclooxygenase action, i.e. prostanoides, only limited information is available about the endogenous levels of hydroxy-, epoxy- and dihydroxy-FA of linoleic acid (LA), AA, α-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in humans. Particularly, it is unknown how metabolic disorders affect endogenous oxylipin levels in humans. Therefore, in the present study we compared the serum concentrations of 44 oxylipins in 20 normolipidemic with 20 hyperlipidemic (total cholesterol >200 mg/dl; LDL-C>130 mg/dl; TG>150 mg/dl) men (age 29-51 y). The serum concentration varied strongly among subjects. For most hydroxy-, epoxy- and dihydroxy-FA the concentrations were comparable to those in plasma reported in earlier studies. Despite the significant change in blood lipid levels the hyperlipidemic group showed only minor differences in oxylipin levels. The hyperlipidemic subjects had a slightly higher serum concentration of 8,9-DiHETrE, 5-HEPE, 10,11-DiHDPE, and a lower concentration of 12,13-DiHOME, 12-HETE, 9,10-DiHODE, and 12,13-DiHODE compared to normolipidemic subjects. Overall the hydroxy-, epoxy- and dihydroxy-FA levels were not changed suggesting that mild combined hyperlipidemia has no apparent effect on the concentration of circulating oxylipins. By contrast, serum levels of several hydroxy-, epoxy-, and dihydroxy-FA are dependent on the individual status of the parent FA. Particularly, a strong correlation between the EPA content in the erythrocyte membrane and the serum concentration of EPA derived oxylipins was observed. Given that the synthesis of EPA from other n-3 FA in humans is low; this suggests that oxylipin levels can be directly influenced by the diet.

Lowering dietary linoleic acid reduces bioactive oxidized linoleic acid metabolites in humans

Linoleic acid (LA) is the most abundant polyunsaturated fatty acid in human diets, a major component of human tissues, and the direct precursor to the bioactive oxidized LA metabolites (OXLAMs), 9- and 13 hydroxy-octadecadienoic acid (9- and 13-HODE) and 9- and 13-oxo-octadecadienoic acid (9- and 13-oxoODE). These four OXLAMs have been mechanistically linked to pathological conditions ranging from cardiovascular disease to chronic pain. Plasma OXLAMs, which are elevated in Alzheimer's dementia and non-alcoholic steatohepatitis, have been proposed as biomarkers useful for indicating the presence and severity of both conditions. Because mammals lack the enzymatic machinery needed for de novo LA synthesis, the abundance of LA and OXLAMs in mammalian tissues may be modifiable via diet. To examine this issue in humans, we measured circulating LA and OXLAMs before and after a 12-week LA lowering dietary intervention in chronic headache patients. Lowering dietary LA significantly reduced the abundance of plasma OXLAMs, and reduced the LA content of multiple circulating lipid fractions that may serve as precursor pools for endogenous OXLAM synthesis. These results show that lowering dietary LA can reduce the synthesis and/or accumulation of oxidized LA derivatives that have been implicated in a variety of pathological conditions. Future studies evaluating the clinical implications of diet-induced OXLAM reductions are warranted.

ω-6 lipids regulate PPAR turnover via reciprocal switch between PGC-1 alpha and ubiquitination

OBJECTIVE

Dietary ω-6 lipids such as linoleic acid and its oxidized forms (13-HPODE OxLA) interact with peroxisome proliferator-activated receptors (PPARs) and elicit pro and anti-atherogenic effects in vascular cells. Ligand-dependent PPAR protein turnover is promoted by ubiquitination, but attenuated by binding to its co-activator, peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1α). The objective of our study was to investigate if the dual atherogenic effects of ω-6 lipids are due to its regulation of PPAR turnover.

METHODS AND RESULTS

In rat aortic smooth muscle cells (RASMCs), oxidized linoleic acid (OxLA) at 10-50 μM induced and stabilized PPARα protein at earlier time points (0-4 h) but suppressed it at 12 h. Conversely, it activated PPARγ protein turnover at a later time point (12 h). Pre-treatment with the proteasome inhibitor (MG132) prevented OxLA mediated loss of PPAR stability and transactivity. Co-immunoprecipitation studies indicated a ligand mediated time-dependent reciprocal exchange of PPAR interaction between ubiquitination and PGC-1α. This ω-6 lipid mediated time-dependent switch between PPAR degradation versus stability helped modulate the pro and anti-atherogenic effects of these dietary lipids.

CONCLUSION

Our findings provide insights into the dual pro and anti-atherogenic effects of dietary ω-6 lipids on vascular cells by the regulation of PPAR turnover.

Transcriptomic analyses of intestinal gene expression of juvenile Atlantic cod (Gadus morhua) fed diets with Camelina oil as replacement for fish oil

For aquaculture of marine species to continue to expand, dietary fish oil (FO) must be replaced with more sustainable vegetable oil (VO) alternatives. Most VO are rich in n-6 polyunsaturated fatty acids (PUFA) and few are rich in n-3 PUFA but Camelina oil (CO) is unique in that, besides high 18:3n-3 and n-3/n-6 PUFA ratio, it also contains substantial long-chain monoenes, commonly found in FO. Cod (initial mass ~1.4 g) were fed for 12 weeks diets in which FO was replaced with CO. Growth performance, feed efficiency and biometric indices were not affected but lipid levels in liver and intestine tended to increase and those of flesh, decrease, with increasing dietary CO although only significantly for intestine. Reflecting diet, tissue n-3 long-chain PUFA levels decreased whereas 18:3n-3 and 18:2n-6 increased with inclusion of dietary CO. Dietary replacement of FO by CO did not induce major metabolic changes in intestine, but affected genes with potential to alter cellular proliferation and death as well as change structural properties of intestinal muscle. Although the biological effects of these changes are unclear, given the important role of intestine in nutrient absorption and health, further attention should be given to this organ in future.

Atherogenic ω-6 Lipids Modulate PPAR- EGR-1 Crosstalk in Vascular Cells

Atherogenic ω-6 lipids are physiological ligands of peroxisome proliferator-activated receptors (PPARs) and elicit pro- and antiatherogenic responses in vascular cells. The objective of this study was to investigate if ω-6 lipids modulated the early growth response-1 (Egr-1)/PPAR crosstalk thereby altering vascular function. Rat aortic smooth muscle cells (RASMCs) were exposed to ω-6 lipids, linoleic acid (LA), or its oxidized form, 13-HPODE (OxLA) in the presence or absence of a PPARα antagonist (MK886) or PPARγ antagonist (GW9662) or PPAR-specific siRNA. Our results demonstrate that ω-6 lipids, induced Egr-1 and monocyte chemotactic protein-1 (MCP-1) mRNA and protein levels at the acute phase (1-4 hrs) when PPARα was downregulated and at subacute phase (4-12 hrs) by modulating PPARγ, thus resulting in altered monocyte adhesion to RASMCs. We provide novel insights into the mechanism of action of ω-6 lipids on Egr-1/PPAR interactions in vascular cells and their potential in altering vascular function.

Comparison of lipid content and fatty acid composition between Tuber fermentation mycelia and natural fruiting bodies

A comparison of lipid content and fatty acid (FA) composition between Tuber fermentation mycelia and natural fruiting bodies indicates that the lipid content in Tuber fermentation mycelia is higher than that in fruiting bodies. Unsaturated FAs (particularly linoleic acid and oleic acid) were the predominant constituents in total FAs in both Tuber fermentation mycelia and fruiting bodies. A total of 23 FAs, including arachidonic, eicosapentaenoic, docosahexaenoic, and γ-linolenic acids, were first identified in the Tuber species. A hierarchical clustering analysis showed that the FA profile of fermentation mycelia was quite similar, regardless of Tuber species. However, the FA profile of the fruiting bodies was significantly influenced by its species and habitat environments. Interestingly, the FA profile of the Tuber indicum and Tuber aestivum fruiting bodies was nearly identical to that of the Tuber fermentation mycelia, which partially confirms the similarity between the Tuber fermentation mycelia and the fruiting bodies.

Determinants of the omega-3 index in a Mediterranean population at increased risk for CHD

The omega-3 index, defined as the sum of EPA and DHA in erythrocyte membranes expressed as a percentage of total fatty acids, has been proposed as both a risk marker and risk factor for CHD death. A major determinant of the omega-3 index is EPA+DHA intake, but the impact of other dietary fatty acids has not been investigated. In a cross-sectional study on 198 subjects (102 men and 96 women, mean age 66 years) at high cardiovascular risk living in Spain, the country with low rates of cardiac death despite a high prevalence of cardiovascular risk factors, dietary data were acquired from FFQ and blood cell membrane fatty acid composition was measured by GC. The average consumption of EPA+DHA was 0·9 g/d and the mean omega-3 index was 7·1 %. In multivariate models, EPA+DHA intake was the main predictor of the omega-3 index but explained only 12 % of its variability (P < 0·001). No associations with other dietary fatty acids were observed. Although the single most influential determinant of the omega-3 index measured here was the intake of EPA+DHA, it explained little of the former's variability; hence, the effects of other factors (genetic, dietary and lifestyle) remain to be determined. Nevertheless, the high omega-3 index could at least partially explain the paradox of low rates of fatal CHD in Spain despite a high background prevalence of cardiovascular risk factors.

Linoleic acid and butyrate synergize to increase Bcl-2 levels in colonocytes

The biological properties of polyunsaturated fatty acid (PUFA) classes have been the source of much contention. For example, n-3 PUFA are chemoprotective, whereas n-6 PUFA may promote tumor development. Since dietary components can have combinatorial effects, we further examined the apoptotic properties of n-3 or n-6 fatty acids when combined with different fiber sources. Mice were fed diets supplemented with either fish oil (FO; enriched in n-3 PUFA) or corn oil (CO; enriched in n-6 PUFA) and nonfermentable (cellulose) or fermentable (pectin) fiber sources. In complementary experiments, immortalized young adult mouse colonic (YAMC) cells were treated with docosahexaenoic acid (DHA; 22:6n-3) or linoleic acid (LA; 18:2n-6) with or without butyrate. Mice fed a FO and pectin diet had significantly (p < 0.05) increased levels of apoptosis in colonocytes compared to all other diets. Similarly, apoptosis was highly induced in DHA and butyrate cotreated YAMC cells. In contrast, in both YAMC and mouse models, LA/CO with butyrate/pectin treatment reduced apoptosis and enhanced expression of bcl-2. The LA and butyrate induced antiapoptotic phenotype was reversed by knocking down bcl-2 using targeted siRNA. In comparison, overexpression of bcl-2 blocked the proapoptotic effect of DHA and butyrate. These data provide new mechanistic insights into the regulation of apoptosis by dietary PUFA and fiber.

Polyunsaturated fatty acids and cardiovascular disease

Replacing saturated with polyunsaturated (PUFAs) rather than monounsaturated fatty acids or carbohydrates results in cardiovascular prevention over a wide range of intakes. The mechanisms by which PUFAs reduce cardiovascular risk are manifold, and the extent and precise nature of their activities is the subject of several investigations, spanning from in vitro mechanistic studies to human intervention trials. This article reviews the most up-to-date evidence of the association between PUFA consumption and reduced cardiovascular mortality.