Stearidonic acid: is there a role in the prevention and management of type 2 diabetes mellitus?

Systems genetics of metabolic health in the BXD mouse genetic reference population

Susceptibility to metabolic syndrome (MetS) is dependent on genetics, environment, and gene-by-environment interactions, rendering the study of underlying mechanisms challenging. The majority of experiments in model organisms do not incorporate genetic variation and lack specific evaluation criteria for MetS. Here, we derived a continuous metric, the metabolic health score (MHS), based on standard clinical parameters and defined its molecular signatures in the liver and circulation. In human UK Biobank, the MHS associated with MetS status and was predictive of future disease incidence, even in individuals without MetS. Using quantitative trait locus analyses in mice, we found two MHS-associated genetic loci and replicated them in unrelated mouse populations. Through a prioritization scheme in mice and human genetic data, we identified TNKS and MCPH1 as candidates mediating differences in the MHS. Our findings provide insights into the molecular mechanisms sustaining metabolic health across species and uncover likely regulators. A record of this paper's transparent peer review process is included in the supplemental information.

Epigenome-wide association study of dietary fatty acid intake

BACKGROUND

Dietary intake of n-3 polyunsaturated fatty acids (PUFA) may have a protective effect on the development of cardiovascular diseases, diabetes, depression and cancer, while a high intake of n-6 PUFA was often reported to be associated with inflammation-related traits. The effect of PUFAs on health outcomes might be mediated by DNA methylation (DNAm). The aim of our study is to identify the impact of PUFA intake on DNAm in the Cooperative Health Research in the Region of Augsburg (KORA) FF4 cohort and the Leiden Longevity Study (LLS).

RESULTS

DNA methylation levels were measured in whole blood from the population-based KORA FF4 study (N = 1354) and LLS (N = 448), using the Illumina MethylationEPIC BeadChip and Illumina HumanMethylation450 array, respectively. We assessed associations between DNAm and intake of eight and four PUFAs in KORA and LLS, respectively. Where possible, results were meta-analyzed. Below the Bonferroni correction threshold (p < 7.17 × 10-8), we identified two differentially methylated positions (DMPs) associated with PUFA intake in the KORA study. The DMP cg19937480, annotated to gene PRDX1, was positively associated with docosahexaenoic acid (DHA) in model 1 (beta: 2.00 × 10-5, 95%CI: 1.28 × 10-5-2.73 × 10-5, P value: 6.98 × 10-8), while cg05041783, annotated to gene MARK2, was positively associated with docosapentaenoic acid (DPA) in our fully adjusted model (beta: 9.80 × 10-5, 95%CI: 6.25 × 10-5-1.33 × 10-4, P value: 6.75 × 10-8). In the meta-analysis, we identified the CpG site (cg15951061), annotated to gene CDCA7L below Bonferroni correction (1.23 × 10-7) associated with eicosapentaenoic acid (EPA) intake in model 1 (beta: 2.00 × 10-5, 95% CI: 1.27 × 10-5-2.73 × 10-5, P value = 5.99 × 10-8) and we confirmed the association of cg19937480 with DHA in both models 1 and 2 (beta: 2.07 × 10-5, 95% CI: 1.31 × 10-5-2.83 × 10-5, P value = 1.00 × 10-7 and beta: 2.19 × 10-5, 95% CI: 1.41 × 10-5-2.97 × 10-5, P value = 5.91 × 10-8 respectively).

CONCLUSIONS

Our study identified three CpG sites associated with PUFA intake. The mechanisms of these sites remain largely unexplored, highlighting the novelty of our findings. Further research is essential to understand the links between CpG site methylation and PUFA outcomes.

Integrated metabolome and transcriptome analyses provide insight into the effect of red and blue LEDs on the quality of sweet potato leaves

Red and blue light-emitting diodes (LEDs) affect the quality of sweet potato leaves and their nutritional profile. Vines cultivated under blue LEDs had higher soluble protein contents, total phenolic compounds, flavonoids, and total antioxidant activity. Conversely, chlorophyll, soluble sugar, protein, and vitamin C contents were higher in leaves grown under red LEDs. Red and blue light increased the accumulation of 77 and 18 metabolites, respectively. Alpha-linoleic and linolenic acid metabolism were the most significantly enriched pathways based on Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. A total of 615 genes were differentially expressed between sweet potato leaves exposed to red and blue LEDs. Among these, 510 differentially expressed genes were upregulated in leaves grown under blue light compared with those grown under red light, while the remaining 105 genes were expressed at higher levels in the latter than in the former. Among the KEGG enrichment pathways, blue light significantly induced anthocyanin and carotenoid biosynthesis structural genes. This study provides a scientific reference basis for using light to alter metabolites to improve the quality of edible sweet potato leaves.

Possible Health Effects of a Wax Ester Rich Marine Oil

The consumption of seafood and the use of fish oil for the production of nutraceuticals and fish feed have increased over the past decades due the high content of long-chain polyunsaturated omega-3 fatty acids. This increase has put pressure on the sustainability of fisheries. One way to overcome the limited supply of fish oil is to harvest lower in the marine food web. Calanus finmarchicus, feeding on phytoplankton, is a small copepod constituting a considerable biomass in the North Atlantic and is a novel source of omega-3 fatty acids. The oil is, however, different from other commercial marine oils in terms of chemistry and, possibly, bioactivity since it contains wax esters. Wax esters are fatty acids that are esterified with alcohols. In addition to the long-chain polyunsaturated omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the oil is also rich in stearidonic acid (SDA), long-chain monounsaturated fatty acids, and the long-chain fatty alcohols eicosenol and docosenol. Recent animal studies have indicated anti-inflammatory and anti-obesogenic actions of this copepod oil beyond that provided by EPA and DHA. This review will discuss potential mechanisms behind these beneficial effects of the oil, focusing on the impact of the various components of the oil. The health effects of EPA and DHA are well recognized, whereas long-chain monounsaturated fatty acids and long-chain fatty alcohols have to a large degree been overlooked in relation to human health. Recently, however the fatty alcohols have received interest as potential targets for improved health via conversion to their corresponding fatty acids. Together, the different lipid components of the oil from C. finmarchicus may have potential as nutraceuticals for reducing obesity and obesity-related metabolic disorders.

Dietary Fatty Acids and Their Potential for Controlling Metabolic Diseases Through Activation of FFA4/GPR120

It is well known that the amount and type of ingested fat impacts the development of obesity and metabolic diseases, but the potential for beneficial effects from fat has received less attention. It is becoming clear that the composition of the individual fatty acids in diet is important. Besides acting as precursors of potent signaling molecules, dietary fatty acids act directly on intracellular and cell surface receptors. The free fatty acid receptor 4 (FFA4, previously GPR120) is linked to the regulation of body weight, inflammation, and insulin resistance and represents a potential target for the treatment of metabolic disorders, including type 2 diabetes and obesity. In this review, we discuss the various types of dietary fatty acids, the link between FFA4 and metabolic diseases, the potential effects of the individual fatty acids on health, and the ability of fatty acids to activate FFA4. We also discuss the possibility of dietary schemes that implement activation of FFA4.

Consumption of echium oil increases EPA and DPA in blood fractions more efficiently compared to linseed oil in humans

Background

A plant-based strategy to improve long-chain (LC) omega (n)-3 PUFA supply in humans involves dietary supplementation with oils containing α-linolenic acid (ALA) alone or in combination with stearidonic acid (SDA). The study aimed to compare the effects of echium oil (EO) and linseed oil (LO) on LC n-3 PUFA accumulation in blood and on clinical markers.

Methods

In two double-blind, parallel-arm, randomized controlled studies, all volunteers started with 17 g/d run-in oil (2 weeks). Thereafter, subjects received diets enriched in study 1 with EO (5 g ALA + 2 g SDA; n = 59) or in study 2 with LO (5 g ALA; n = 59) daily for 8 weeks. The smaller control groups received fish oil (FO; n = 19) or olive oil (OO; n = 18). Participants were instructed to restrict their dietary n-3 PUFA intake throughout the studies (e.g., no fish). To investigate the influence of age and BMI on the conversion of ALA and SDA as well as clinical markers, the subjects recruited for EO and LO treatment were divided into three subgroups (two age groups 20–35 y; 49–69 y with BMI 18–25 kg/m² and one group with older, overweight subjects (age 49–69 y; BMI >25 kg/m²).

Results

In plasma, red blood cells (RBC), and peripheral blood mononuclear cells (PBMC), EPA and docosapentaenoic acid (DPA) were ~25 % higher following EO compared to LO. Comparing all treatments, the effectiveness of increasing EPA and DPA in plasma, RBC, and PBMC was on average 100:25:10:0 and 100:50:25:0 for FO:EO:LO:OO, respectively. EO led to a lower arachidonic acid/EPA-ratio compared to LO in plasma, RBC, and PBMC. Following EO, final DHA was not greater compared to LO. Higher BMI correlated negatively with increases in plasma EPA and DPA after EO supplementation, but not after LO supplementation. Decreasing effect on plasma LDL-C and serum insulin was greater with EO than with LO.

Conclusions

Daily intake of SDA-containing EO is a better supplement than LO for increasing EPA and DPA in blood. However, neither EO nor LO maintained blood DHA status in the absence of fish/seafood consumption.

Trial registration

ClinicalTrials.gov Reg No. NCT01856179; ClinicalTrials.gov Reg No. NCT01317290.

The impact of polyunsaturated fatty acid-based dietary supplements on disease biomarkers in a metabolic syndrome/diabetes population

Background

Ingestion of polyunsaturated fatty acids (PUFAs) has been proposed to influence several chronic diseases including coronary heart disease (CHD) and type-2 diabetes (T2D).There is strong evidence that omega-3 (n-3) PUFAs provide protection against CHD and biomarkers of atherosclerosis. In contrast, there is more limited and inconsistent data for T2D. Few studies have examined the impact of n-3 PUFA-containing botanical oils on T2D.

Methods

Fifty-nine subjects with early-stageT2D or metabolic syndrome participated in an 8-week, randomized, single-blind, parallel intervention study and were provided PUFA-containing oils. Individuals received either corn oil (CO), a botanical oil (BO) combination (borage [Borago officinalis L.]/echium oil [Echium plantagineum L.]) or fish oil (FO). The BO combination was enriched in alpha-linolenic, gamma-linolenic, and stearidonic acids and the FO in eicosapentaenoic and docosahexaenoic acids. Serum fatty acids and other serum lipids(triglycerides and total, HDL and LDL cholesterol), as well as markers of inflammation (leptin, and C-reactive protein) and glucose regulation (glucose and hemoglobin A1c) were assessed from fasting participants at baseline and after the intervention.

Results

Compliance was verified by expected increases in specific PUFAs in each of the three oil arms. Participants in the CO group showed no differences in serum lipids, markers of inflammation or glucose regulation between pre- and post-treatment measures. Supplementation with BO significantly lowered total and LDL cholesterol levels and FO reduced serum triglycerides, hemoglobin A1c and increased HDL-cholesterol.

Conclusion

Short-term dietary supplementation with BO and FO improved biomarkers associated with T2D/metabolic syndrome.

Trial registration

Clinicaltrial.gov NCT01145066

Dietary echium oil increases long-chain n-3 PUFAs, including docosapentaenoic acid, in blood fractions and alters biochemical markers for cardiovascular disease independently of age, sex, and metabolic syndrome

Dietary supplementation with echium oil (EO) containing stearidonic acid (SDA) is a plant-based strategy to improve long-chain (LC) n-3 (ω-3) polyunsaturated fatty acid (PUFA) status in humans. We investigated the effect of EO on LC n-3 PUFA accumulation in blood and biochemical markers with respect to age, sex, and metabolic syndrome. This double-blind, parallel-arm, randomized controlled study started with a 2-wk run-in period, during which participants (n = 80) were administered 17 g/d run-in oil. Normal-weight individuals from 2 age groups (20-35 and 49-69 y) were allotted to EO or fish oil (FO; control) groups. During the 8-wk intervention, participants were administered either 17 g/d EO (2 g SDA; n = 59) or FO [1.9 g eicosapentaenoic acid (EPA); n = 19]. Overweight individuals with metabolic syndrome (n = 19) were recruited for EO treatment only. During the 10-wk study, the participants followed a dietary n-3 PUFA restriction, e.g., no fish. After the 8-wk EO treatment, increases in the LC n-3 metabolites EPA (168% and 79%) and docosapentaenoic acid [DPA (68% and 39%)] were observed, whereas docosahexaenoic acid (DHA) decreased (-5% and -23%) in plasma and peripheral blood mononuclear cells, respectively. Compared with FO, the efficacy of EO to increase EPA and DPA in blood was significantly lower (∼25% and ∼50%, respectively). A higher body mass index (BMI) was associated with lower relative and net increases in EPA and DPA. Compared with baseline, EO significantly reduced serum cholesterol, LDL cholesterol, oxidized LDL, and triglyceride (TG), but also HDL cholesterol, regardless of age and BMI. In the FO group, only TG decreased. Overall, daily intake of 15-20 g EO increased EPA and DPA in blood but had no influence on DHA. EO lowered cardiovascular risk markers, e.g., serum TG, which is particularly relevant for individuals with metabolic syndrome. Natural EO could be a noteworthy source of n-3 PUFA in human nutrition.

Alternative sources of omega-3 fats: can we find a sustainable substitute for fish?

Increasing demand for eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) containing fish oils is putting pressure on fish species and numbers. Fisheries provide fish for human consumption, supplement production and fish feeds and are currently supplying fish at a maximum historical rate, suggesting mass-scale fishing is no longer sustainable. However, the health properties of EPA and DHA long-chain (LC) omega-3 polyunsaturated fatty acids (PUFA) demonstrate the necessity for these oils in our diets. EPA and DHA from fish oils show favourable effects in inflammatory bowel disease, some cancers and cardiovascular complications. The high prevalence of these diseases worldwide indicates the requirement for alternative sources of LC-PUFA. Strategies have included plant-based fish diets, although this may compromise the health benefits associated with fish oils. Alternatively, stearidonic acid, the product of α-linolenic acid desaturation, may act as an EPA-enhancing fatty acid. Additionally, algae oils may be a promising omega-3 PUFA source for the future. Algae are beneficial for multiple industries, offering a source of biodiesel and livestock feeds. However, further research is required to develop efficient and sustainable LC-PUFA production from algae. This paper summarises the recent research for developing prospective substitutes for omega-3 PUFA and the current limitations that are faced.

Omega-3 fatty acid supplementation and cardiovascular disease

Epidemiological studies on Greenland Inuits in the 1970s and subsequent human studies have established an inverse relationship between the ingestion of omega-3 fatty acids [C(20-22) ω 3 polyunsaturated fatty acids (PUFA)], blood levels of C(20-22) ω 3 PUFA, and mortality associated with cardiovascular disease (CVD). C(20-22) ω 3 PUFA have pleiotropic effects on cell function and regulate multiple pathways controlling blood lipids, inflammatory factors, and cellular events in cardiomyocytes and vascular endothelial cells. The hypolipemic, anti-inflammatory, anti-arrhythmic properties of these fatty acids confer cardioprotection. Accordingly, national heart associations and government agencies have recommended increased consumption of fatty fish or ω 3 PUFA supplements to prevent CVD. In addition to fatty fish, sources of ω 3 PUFA are available from plants, algae, and yeast. A key question examined in this review is whether nonfish sources of ω 3 PUFA are as effective as fatty fish-derived C(20-22) ω 3 PUFA at managing risk factors linked to CVD. We focused on ω 3 PUFA metabolism and the capacity of ω 3 PUFA supplements to regulate key cellular events linked to CVD. The outcome of our analysis reveals that nonfish sources of ω 3 PUFA vary in their capacity to regulate blood levels of C(20-22) ω 3 PUFA and CVD risk factors.

Conclusions and recommendations from the symposium, Heart Healthy Omega-3s for Food: Stearidonic Acid (SDA) as a Sustainable Choice

Faculty who had presented at the symposium "Heart Healthy Omega-3s (n-3 fatty acids) for Food: Stearidonic Acid (SDA) as a Sustainable Choice" met and agreed upon conclusions and recommendations that could be made on the basis of evidence provided at the symposium. The participants also submitted manuscripts relating to their topics and these are presented in this supplement. These manuscripts were reviewed and also contributed to the conclusions and recommendations presented herein. The three major objectives of the symposium were to: 1) increase understanding of the current and emerging knowledge regarding the health benefits of (n-3) fatty acids (FA) including a focus on stearidonic acid (SDA) and EPA; 2) evaluate the importance of increasing (n-3) FA consumption in the US and the current challenge of doing so via mainstream foods; and 3) consider the health and food application benefits of SDA as a precursor to EPA and a plant-based sustainable source of highly unsaturated (n-3) FA for mainstream foods. Specific areas for future research were defined and included in the summary and conclusions herein. Overall evidence-based conclusions included: the current evidence provides a strong rationale for increasing (n-3) FA intakes in the US and other populations; current consumption of (n-3) FA in most populations is either insufficient or not efficient at providing adequate tissue levels of the long-chain (n-3) FA EPA and DHA; SDA in soybean oil appears to be a cost-effective and sustainable plant-based source that could contribute to reaching recommended levels of (n-3) FA intake, but more research and surveillance is needed; and adding SDA-enriched soybean oil to foods should be considered as a natural fortification approach to improving (n-3) FA status in the US and other populations. References for these conclusions and recommendations can be found in the articles included in the supplement.