All beta-glucans are believed to possess a wide spectrum of therapeutic and prophylactic potential, however, recent findings indicate that their properties largely depend on their origin and structure.Cereal β-glucans having a β-1,3 and 1,4 linkages are beneficial for reducing hyperglycaemia and hyperinsulinaemia; they reduce blood cholesterol and the risk of diseases associated with obesity such as hyperlipidaemia, hypercholesterolaemia, cardiovascular diseases, cancer, hypertension, and promote the growth of beneficial intestinal microflora (as a prebiotic).In the gastrointestinal tract, the stomach and small intestine, β-glucans do not undergo enzymatic degradation, but a mucilaginous protective layer is formed which delays the hydrolysis of starch and the absorption of glucose.They also cause the sense of satiety, while having protective benefits if there are gastrointestinal disorders present.The obtained mucus protects the mucous membrane from irritation and bacterial infections.
“Lowering cholesterol by 1% can minimize the risk of coronary heart disease by 2-3 times.”
It can be concluded that beta-glucan impedes the synthesis and absorption of cholesterol and fats, by reducing the quantity of assimilated glucose and delaying the sugar peak. Beta-glucans effectively reduce the caloric content and glycemic index of the meal. A very valuable characteristic of the beta-glucan derived from oats is its prebiotic properties. Beta-glucan is a medium for probiotic bacteria, which cause its partial degradation in the large intestine. In the process of disintegration, certain organic acids are formed, such as: acetone butanoic (butyric acid) and propionic acid (etanol carboxylic acid) which are very important for the proper functioning of the colon. Propionic acid has anti-inflammatory, analgesic and anti-mould properties whereas butyric acid stimulates the immune system of the large intestine and inhibits the growth of carcinogenic bacteria. Beta-glucan reduces the ‘bad’ LDL cholesterol levels, which translates into tangible health benefits. Lowering LDL cholesterol levels by 5-12%, and in people with high levels of LDL cholesterol by up to 20%, can positively influence the proper functioning of the heart and circulation. In one of the clinical trials, people with elevated cholesterol were given a drink with 5 g or 10 g of beta-glucan from oats or barley for 5 consecutive weeks. The levels of lipid, lipoprotein, insulin and glucose in the blood were controlled. It has been found that the consumption of 5 g of beta-glucan from oats improved glucose and lipid metabolism, with no significant effects in the case of the beta-glucan derived from barley.
In another study, beta-glucan form oats (5g) was added to a fruit drink. This cocktail was administered for 3 or 5 weeks to healthy volunteers. This resulted in a decrease in LDL and total cholesterol. A similar effect was observed in patients with high cholesterol levels and co-exisiting diabetes, who were given from 2 to 10 g of oat soluble fibre daily. Why beta-glucan helps to lower cholesterol is still not known for certain. Most likely, this effect is achieved because it mechanically blocks the absorption of cholesterol and glucose, and increases the diameter of the fat emulsion droplets in the small intestine. The results suggest that cereal beta-glucan lowers the absorption and reabsorption of cholesterol, bile acids and their metabolites by increasing the contents of gastrointestinal tract. The beneficial effect of beta-glucan on cholesterol levels may also result from its effects on carbohydrate metabolism.Metabolism of sugars and fats in the body are strongly connected. Insulin is responsible for the increased synthesis of cholesterol. Since beta-glucan reduces the absorption of sugars and secretion of insulin, it may also indirectly contribute to lower cholesterol levels. Furthermore, the presence of beta-glucan increases the diameter of the fat emulsion droplets, which further reduces the absorption of these compounds.
Glucans that do not undergo an enzymatic degradation form a protective mucous layer which delays hydrolysis of starch and the absorption of glucose, reduces the amount of assimilated glucose and also delays the appearance of the sugar peak. It reduces the effective calorific value and the glycemic index of the meal.
Beta-glucans are also used to control glycemic value (blood sugar concentration), which is used in the prophylaxis and treatment of diabetes. It happens because they reduce the glycemic and insulin response of the body after a meal (ie. an increase in blood sugar and insulin – a hormone lowering its concentration). This mechanism helps to avoid large fluctuations in blood sugar, which are particularly dangerous in this disease.
Some research reports that the consumption of beta-glucans improves carbohydrate metabolism to such an extent that it reduces the need for drug therapy.
Fibre consumed in a diet is rich in soluble fractions (betaglucans-glucans) and despite increasing the volume of food, it does not increase its energy value. At the same time, it acts as a filler of gastrointestinal tract which helps satisfy cravings and prolongs satiety
It was agreed that a daily intake of as little as 3 grams of beta-glucans offers beneficial effects (recommendations FDA – Food and Drug Administration).