Yeast β-glucan in the human diet

In recent years, there has been increasing interest in the effect of the use of β-glucan as a dietary supplement. Different studies seek to prove the use of this polysaccharide in the diet has several health benefits. The beneficial effects of consistent intake of β-glucan and its action in reducing cholesterol levels in the blood have been systematically studied. A study of 20 hypercholesterolemic patients, who received daily dietary supplement containing 5.8 g of β-glucan for 4 weeks, reported a 9% decrease in cholesterol level in the intervention group, while there was no difference in the placebo (maltodextrin) group . Nicolosi et al. observed a significant reduction in total and LDL cholesterol in hypercholesterolemic obese patients after 8 weeks of intake of orange juice supplemented with β-glucan. The action of β-glucan on cholesterol reduction can be explained in terms of the reduction in bile reabsorption or the increase in viscosity in the small intestine. However, a more likely explanation relates to the size of the molecule and its subsequent absorption by the intestine. According to Kim et al., molecules of small size, which are consequently less viscous, are less effective in lowering cholesterol. Studies with β-glucan of low molecular size (370,000–1,000,000) reported this polysaccharide ineffective in reducing the cholesterol level , whereas Braaten et al.  reported a significant reduction in cholesterol levels in the blood of patients who included β-glucan of molecular size above 1.2 million in their diet. β-glucans become a great special food in a diet designed to adjunct in diabetic patients. The action of this polymer in lowering blood glucose level is also reported in the literature. Research has demonstrated the antidiabetic effect of IL-1 cytokine, which increases insulin production, resulting in the lowering of blood glucose levels . Since the β-glucan acts on the activation of macrophages, and these are considered the major source of IL-1 in the human body, this polymer becomes useful in diets designed for diabetic patients. According to Regand et al., the physiological activity of β-glucan in reducing glycemic responses has been mostly attributed to its effect in increasing viscosity in the upper digestive tract. The introduction of β-glucan in the diet may decrease the incidence of colds, respiratory diseases, in addition to alleviating the symptoms caused by these diseases, since this polymer increases the body’s potential to defend against invading pathogens. A study with seventy-five marathon runners showed that daily administration of β-glucan can prevent upper respiratory tract (URTI) symptoms and improve overall health and mood following a competitive marathon. More recently, a study of 162 healthy participants with recurring infections who received a diet supplemented with β-(1-3),(1-6) glucan showed a reduction in the number of symptomatic common cold infections by 25% and the mean symptom score was 15% lower compared to the control group.