Lipids and Lipoproteins as Biomarkers of Vascular Complications in Diabetes and Their Modulation by Dietary Phytochemicals

Abstract

Lipids and lipoproteins are predictive biomarkers of vascular events in diabetes and play a critical role in the pathogenesis of macro- and microvascular complications associated with this condition. Diabetic dyslipidemia is principally characterized by quantitative and qualitative lipid abnormalities, such as elevated fasting and postprandial triglycerides, increased production of VLDL and chylomicrons, increased glycation and oxidation of LDL and production of small dense LDL particles that are taken up by macrophages, and low HDL-cholesterol (HDL-C) and increased triglyceride content of HDL. Plant-based diets and dietary phytochemical-containing functional foods and beverages and herbs and spices have been shown to reduce LDL-cholesterol (LDL-C) and triglycerides and/or increase HDL-C in clinical studies of patients with type 2 diabetes. Plant-based diets, especially the Mediterranean diet rich in monounsaturated fats, fiber, and polyphenols, functional foods and beverages such as berries, cocoa, pomegranates, soy, and tea rich in several classes of phytochemicals and soluble fiber, and spices such as cinnamon have been shown to improve atherogenic lipid profiles in clinical studies and thus deserve special attention in the nutritional management of diabetic dyslipidemia. These phytochemical-containing diets and functional foods and beverages have been shown to modulate many pathways of lipid and lipoprotein metabolism, such as inhibiting hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase, the rate-limiting step in cholesterol synthesis, inhibiting cholesterol absorption and chylomicron synthesis, inhibiting action of fat digestive enzymes, and via improving glycemic control in diabetes. These clinical observations need further research in larger studies of patients with diabetic vascular complications.