 This fermentation impacts the expression of many genes within the large intestine, which further affects digestive function and cholesterol and glucose metabolism, as well as the immune system and other systemic functions.Cereal β-glucans from oat, barley, wheat, and rye have been studied for their effects on cholesterol levels in people with normal cholesterol levels and in those with hypercholesterolemia.Intake of oat β-glucan at daily amounts of at least 3 grams lowers total and low-density lipoprotein cholesterol levels by 5 to 10% in people with normal or elevated blood cholesterol levels.