Increase in obesity and metabolic syndrome are associated with increases in insulin resistance (IR) and type 2 diabetes mellitus. Results from animal intervention studies and human epidemiological studies suggest that n-3 polyunsaturated fatty acids can prevent and reverse IR, but results from human intervention studies have varied. Results from some human and animal studies suggest that docosahexaenoic acid (22:6n-3; DHA) may be more effective than eicosapentaenoic acid (20:5n-3; EPA) in the prevention of IR.
By using a placebo-controlled, parallel study design, we examined the effects of DHA supplementation (3 grams/day, 90 days) in the absence of EPA on glucocentric and lipocentric markers of IR in hypertriglyceridemic men (n=14-17/group).
DHA supplementation increased fasting plasma glucose concentration by 4.7% (P<0.05), but did not alter other indices of IR based on fasting (insulin and homeostasis model assessment of insulin resistance [HOMA-IR]) or postprandial insulin and glucose concentrations (areas under curves for insulin and glucose, Matsuda index). Glucose increased by 2.7% in the placebo group and was not significant; increases in glucose in the two groups did not differ from each other. DHA decreased circulating concentrations of several lipocentric markers of IR, including plasma concentrations of nonesterified fatty acids (13.0%), small, dense low-density lipoprotein (LDL) particles (21.7%), and ratio of tryglycerides to high-density lipoprotein cholesterol (TG/HDL-C) (34.0%) (P<0.05). None of the variables changed in the placebo group.
Our results suggest that lipocentric markers of IR are more responsive to DHA supplementation than the glucocentric markers. Future studies with DHA in prediabetic subjects and direct measures of insulin sensitivity are needed.
"It is universally agreed that ω3 FA decrease the production of VLDL, thereby reducing plasma triglycerides by as much as 30-50% . The effects on lipoprotein particle distribution, including a decrease in VLDL size, increases in LDL and HDL size, and increases or decreases in LDL and HDL cholesterol are inconsistent and may be due to differences in the specific effects of the individual long chain ω3 EPA and DHA [10-12] as well as genetic factors , however, the variability in these responses has not been well characterized to date. Additionally, ω3 FA have been implicated in decreasing inflammation via direct effects on lipid signaling mediators, or oxylipins. "
[Show abstract][Hide abstract] ABSTRACT: Conflicting findings in both interventional and observational studies have resulted in a lack of consensus on the benefits of ω3 fatty acids in reducing disease risk. This may be due to individual variability in response. We used a multi-platform lipidomic approach to investigate both the consistent and inconsistent responses of individuals comprehensively to a defined ω3 intervention.
The lipidomic profile including fatty acids, lipid classes, lipoprotein distribution, and oxylipins was examined multi- and uni-variately in 12 healthy subjects pre vs. post six weeks of ω3 fatty acids (1.9 g/d eicosapentaenoic acid [EPA] and 1.5 g/d docosahexaenoic acid [DHA]).
Total lipidomic and oxylipin profiles were significantly different pre vs. post treatment across all subjects (p=0.00007 and p=0.00002 respectively). There was a strong correlation between oxylipin profiles and EPA and DHA incorporated into different lipid classes (r(2)=0.93). However, strikingly divergent responses among individuals were also observed. Both ω3 and ω6 fatty acid metabolites displayed a large degree of variation among the subjects. For example, in half of the subjects, two arachidonic acid cyclooxygenase products, prostaglandin E2 (PGE2) and thromboxane B2 (TXB2), and a lipoxygenase product, 12-hydroxyeicosatetraenoic acid (12-HETE) significantly decreased post intervention, whereas in the other half they either did not change or increased. The EPA lipoxygenase metabolite 12-hydroxyeicosapentaenoic acid (12-HEPE) varied among subjects from an 82% decrease to a 5,000% increase.
Our results show that certain defined responses to ω3 fatty acid intervention were consistent across all subjects. However, there was also a high degree of inter-individual variability in certain aspects of lipid metabolism. This lipidomic based phenotyping approach demonstrated that individual responsiveness to ω3 fatty acids is highly variable and measurable, and could be used as a means to assess the effectiveness of ω3 interventions in modifying disease risk and determining metabolic phenotype.
PLoS ONE 10/2013; 8(10):e76575. DOI:10.1371/journal.pone.0076575 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Omega-3 fatty acids and fenofibrate are both used to treat patients with hypertriglyceridemia. However, a head-to-head comparison of the lipoprotein and metabolic effects of these two medicines has not been published.
This was a randomized, single-blind, placebo-controlled, parallel study. Age, sex, and body mass index were matched among groups. All patients were recommended to maintain a low fat diet. Fifty patients in each group were given placebo, omega-3 fatty acids 2 g (most commonly used dosage in Korean patients), or fenofibrate 160 mg, respectively daily for 2 months.
Omega-3 fatty acids therapy decreased triglycerides by 21% and triglycerides/HDL cholesterol and improved flow-mediated dilation (P<0.01), however, did not significantly change insulin, plasma adiponectin levels, and insulin sensitivity (determined by QUICKI) relative to baseline measurements. Fenofibrate therapy decreased total cholesterol, triglycerides by 29%, and triglycerides/HDL-cholesterol (all P<0.01) and improved flow-mediated dilation when compared with baseline. When compared with placebo and omega-3 fatty acids, fenofibrate therapy decreased non-HDL cholesterol (P<0.001) and triglycerides/HDL cholesterol (P=0.016) while increasing HDL cholesterol (P<0.001) and apolipoprotein AI (P=0.001). Of note, when compared with omega-3 fatty acids, fenofibrate therapy decreased fasting insulin (P=0.023) and increased plasma adiponectin (P=0.002) and insulin sensitivity (P=0.015).
Omega-3 fatty acids and fenofibrate therapy promoted similar changes in triglycerides and endothelium-dependent dilation. However, fenofibrate therapy had substantially better effects on lipoprotein and metabolic profiles in patients with hypertriglyceridemia.
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVE
Long-chain n-3 polyunsaturated fatty acids supplements (n-3 PUFA) may have renoprotective effects in patients with diabetes, but previous trials have been inconsistent. We performed a randomized controlled trial of n-3 PUFA supplementation on urine albumin excretion and markers of kidney injury in adults with type 2 diabetes.RESEARCH DESIGN AND METHODS
We conducted a randomized, placebo-controlled, two-period crossover trial to test the effects of 4 g/day of n-3 PUFA supplementation on markers of glomerular filtration and kidney injury in adults with adult-onset diabetes and greater than or equal to trace amounts of proteinuria. Each period lasted 6 weeks and was separated by a 2-week washout. The main outcome was urine albumin excretion and, secondarily, markers of kidney injury (kidney injury molecule-1, N-acetyl β-d-glucosaminidase [NAG], neutrophil gelatinase-associated lipocalin [NGAL], and liver fatty acid-binding protein [LFABP]), serum markers of kidney function (cystatin C, β(2)-microglobulin, and creatinine), and estimated glomerular filtration rate (eGFR).RESULTSOf the 31 participants, 29 finished both periods. A total of 55% were male, and 61% were African American; mean age was 67 years. At baseline, mean BMI was 31.6 kg/m(2), median eGFR was 76.9 mL/min/1.73 m(2), and median 24-h urine albumin excretion was 161 mg/day. Compared with placebo, n-3 PUFA had nonsignificant effects on urine albumin excretion (-7.2%; 95% CI -20.6 to 8.5; P = 0.35) and significant effects on urine NGAL excretion (-16% [-29.1 to -0.5%]; P = 0.04). There was no effect on serum markers of kidney function or eGFR. In subgroup analyses, there were significant decreases in 24-h urinary excretion of albumin, NGAL, LFABP, and NAG among participants taking medications that block the renin-angiotensin-aldosterone system (RAAS).CONCLUSIONS
These results suggest a potential effect of n-3 PUFA supplementation on markers of kidney injury in patients with diabetes and early evidence of kidney disease. In the context of prior studies, these results provide a strong rationale for long-term trials of n-3 PUFA on chronic kidney disease progression.
Diabetes care 12/2012; 36(6). DOI:10.2337/dc12-1940 · 8.42 Impact Factor
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