This review provides an overview of the major findings of clinical studies on hypocholesterolemic effects of soluble dietary fibers (SDFs). The extent of cholesterol lowering depends on the type of dietary fiber, amount of fiber consumed, length of adaptation period, and nature of the diet. The mechanism of action of SDFs in lowering cholesterol levels is not yet fully delineated. Studies carried out so far support the role of increased bile acid excretion. SDF produces short chain fatty acids (SCFAs) which may impact cholesterol synthesis. Flaxseed contains about 30 % dietary fibers with water-soluble polymers including arabinoxylans and various amounts of galactose and fructose. Flaxseed fibers form highly viscous solutions upon hydration.
Consumption of dietary soluble fibers has been associated with health benefits such as reduced lipid levels, lower blood pressure, improved blood glucose control, weight loss, improved immune function, and reduced inflammation. Many of these health benefits relate to a reduced risk of developing cardiovascular disease. In this paper, we have reviewed recent studies on the hypocholesterolemic effects of dietary soluble fibers as well as fiber-rich foods. Findings include the following: (a) consumption of water-soluble, viscous-forming fibers can reduce total and low-density lipoprotein cholesterol levels by about 5-10 %; (b) minimal changes of high-density lipoprotein cholesterol or triglyceride levels were observed; (c) cholesterol-lowering properties of soluble fibers depend on their physical and chemical properties; and (d) medium to high molecular weight fibers are more effective in reducing lipid levels. Hypocholesterolemic benefits were also observed with some fiber-rich foods, such as whole oats, whole barley, legumes, peas, beans, flax seeds, apples, and citrus foods.Link to Full Text