Why whole grains are protective: biological mechanisms

• Published in: Proceedings of the Nutrition Society Vol. 62; no. 1; pp. 129 - 134
• Main Author: Slavin, Joanne
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.02.2003; CABI Pub. on behalf of the Nutrition Society
• Subjects: Antioxidants; Antioxidants - physiology; Barley; Biological effects; biomarkers; Blood; blood lipids; breast neoplasms; Cancer; Carbohydrates; Cardiovascular diseases; chemistry; chronic diseases; Chronic illnesses; Colon; Colon - metabolism; Colon - microbiology; colorectal neoplasms; Diabetes; Dietary Carbohydrates; Dietary Carbohydrates - metabolism; Dietary fiber; Dietary Fiber - metabolism; Dietary minerals; dietary nutrient sources; digestion; Disease; disease prevention; Edible Grain; Edible Grain - chemistry; Edible Grain - physiology; energy; epidemiological studies; Fatty acids; Fermentation; Glucose; Glucose - metabolism; Glycemic index; Grain; grain consumption; Health risks; Human subjects; Humans; Insulin; Insulin - metabolism; lignans; Lipids; metabolism; microbiology; Minerals; Nutrients; Nutrition research; Obesity; oligosaccharides; Oligosaccharides - metabolism; Phenols; Physiology; phytic acid; Phytochemicals; plant stanols; resistant starch; risk; Session: Health effects of whole grains; short chain fatty acids; small intestine; Starch; Starch - metabolism; trace elements; Vitamins; Weight control; weight loss; whole grain foods; United States > US; Glucose and insulin: Antioxidants; Large bowel; Whole grains; Bioactive compounds
• ISSN: 0029-6651; 1475-2719
• DOI: 10.1079/PNS2002221

Epidemiological studies find that whole-grain intake is protective against cancer, cardiovascular disease, diabetes and obesity. Potential mechanisms for this protection are diverse since whole grains are rich in nutrients and phytochemicals. First, whole grains are concentrated sources of dietary fibre, resistant starch and oligosaccharides, carbohydrates that escape digestion in the small intestine and are fermented in the gut, producing short-chain fatty acids (SCFA). SCFA lower colonic pH, serve as an energy source for the colonocytes and may alter blood lipids. These improvements in the gut environment may provide immune protection beyond the gut. Second, whole grains are rich in antioxidants, including trace minerals and phenolic compounds, and these compounds have been linked to disease prevention. Additionally, whole grains mediate insulin and glucose responses. Although lower glycaemic load and glycaemic index have been linked to diabetes and obesity, risk of cancers such as colon and breast cancer have also been linked to high intake of readily-available carbohydrate. Finally, whole grains contain many other compounds that may protect against chronic disease. These compunds include phytate, phyto-oestrogens such as lignan, plant stanols and sterols, and vitamins and minerals. As a consequence of the traditional models of conducting nutrition studies on isolated nutrients, few studies exist on the biological effects of increased whole-grain intake. The few whole-grain feeding studies that are available show improvements in biomarkers with whole-grain consumption, such as weight loss, blood lipid improvement and antioxidant protection.