The Role of Consumption of Alpha-Linolenic, Eicosapentaenoic and Docosahexaenoic Acids in Human Metabolic Syndrome and Type 2 Diabetes- A Mini-Review

Abstract

The human metabolic syndrome and its frequent sequela, type 2 diabetes are epidemic around the world. Alpha-linolenic acid (ALA, 18:3 n-3), eicosapentaenoic acid (EPA, 20:5 n-3) and docosahexaenoic acid (DHA, 22:6 n-3) consumption ameliorates some of these epidemics' features thus leading one to question if consumption of EPA and DHA, and their metabolic precursor ALA reduce the conversion of metabolic syndrome to type 2 diabetes and reduce the major cause of death in the metabolic syndrome and type 2 diabetes-myocardial infarction. Contributing to myocardial infarction are metabolic syndrome's features of dyslipidemia (including elevated total cholesterol and LDL-c), oxidation, inflammation, hypertension, glucose intolerance, overweight and obesity. Inflammation, glucose and lipid levels are variously influenced by disturbances in various adipocytokines which are in turn positively impacted by n-3 polyunsaturated fatty acid consumption. Type 2 diabetes has all these features though elevated total cholesterol and LDL-c are rarer. It is concluded that EPA and DHA consumption significantly benefits metabolic syndrome and type 2 diabetes primarily in terms of dyslipidemia (particularly hypertriglyceridemia) and platelet aggregation with their impact on blood pressure, glucose control, inflammation and oxidation being less established. There is some evidence that EPA and/or DHA consumption, but no published evidence that ALA reduces conversion of metabolic syndrome to type 2 diabetes and reduces death rates due to metabolic syndrome and type 2 diabetes. ALA's only published significance appears to be platelet aggregation reduction in type 2 diabetes.

Docosahexaenoic Acid Content in Plasma Phospholipids and Desaturase Indices in Obese Children

“…There is some evidence that EPA and DHA consumption significantly benefits metabolic syndrome in terms of dyslipidemia, particularly hypertriglyceridemia 32) . In animal studies, various mechanisms have been reported: increased fatty acid oxidation in the liver 33) , inhibition of hormone-sensitive lipase and VLDL secretion, and increased lipoprotein lipase activity 34) .…”

Polyunsaturated Fatty Acid Levels of Serum and Red Blood Cells in Apparently Healthy Japanese Subjects Living in an Urban Area

“…Although the precise mechanisms are still unknown, a recent paper reported that n-3 PUFA exerts a tissue-specific regulatory effect on phosphatidylinositol 3'-kinase, which acts as an important regulator of insulin signaling in rats 39) . In addition, inflammatory responses, including interleukin-6, tumor necrosis factor-, and adipocytokines, might be involved in the association between PUFA and insulin resistance 40) . In the present study, no significant associations in EPA/AA levels in serum or RBCs between subjects with and without MetS were observed.…”

A high-protein low-fat diet is more effective in improving blood pressure and triglycerides in calorie-restricted obese individuals with newly diagnosed type 2 diabetes

“…Liu et al (2002) in a metaanalysis of nine cross-sectional studies found a significant inverse association between dietary protein and blood pressure in both genders. It has been suggested that potentially protein intake could influence arterial BP through the actions of its constituent amino acids (Ginsberg, 2000;Barre, 2007). In addition, insulin's role in hypertension may be somewhat more direct, with hyperinsulinemia potentially leading to salt and water retention (Storlien et al, 1996).…”