Oatmeal contains soluble fiber (pectin, glucan, gums, psyllium), which reduces low-density lipoprotein (LDL) cholesterol, the "bad" cholesterol. In clinical studies the effect varies from 0% to 18% dependent upon the type of soluble fiber, dosage, background diet and dietary control.
The first study to reveal that oat consumption reduced plasma cholesterol levels goes back to 1963. By enriching bread with rolled oat, the authors observed an 11% reduction in total cholesterol levels. Since then, a multitude of in vivo and in vitro investigations have been conducted to understand the reasons behind this positive effect.
Oat β-glucan, the main soluble fiber found in oats, is seen as the main active component responsible for their cholesterol-lowering effect. Beta-glucan occurs naturally in the bran of grasses such as barley, oats and rye. Barley bran is 7% beta-glucan, oat bran 5%, and rye bran 2%. However, barley is less palatable than oats and eaten less frequently in the diet, therefore majority of research has been carried out into the cholesterol-lowering effect on oat β-glucan.
It has been established that subjects with mildly elevated cholesterol levels have to consume at least 3 g of β-glucan per day to observe a significant reduction in their serum total- and low-density lipoprotein- (LDL) cholesterol levels.
β-glucan is located primarily in the endosperm cell wall of oats. It is composed of glucose molecules with mixed β -(1→4) and β -(1→3) bonds. This specific chemical structure is responsible for physical properties, such as viscosity and solubility, as well as the potential to influence cholesterol metabolism.
During digestion β-glucan is believed to increase intestinal viscosity and bind the bile acids and cholesterol from food, carrying them out of the body in faeces. As a result the liver must increase synthesis of bile acids, requiring increased LDL cholesterol uptake from the bloodstream and lowering blood cholesterol levels as a result.
Eating oats can lower blood cholesterol levels
