Statement from Dr. Claude Lenfant, Director, National Heart, Lung, and Blood Institute
High fiber diets may protect against obesity and cardiovascular disease (CVD) in healthy young adults by lowering insulin levels. This is one of the findings of an analysis of participants in the CARDIA Study (Coronary Artery Risk Development in Young Adults), sponsored by the National Heart, Lung, and Blood Institute (NHLBI). CARDIA is a long-term study examining the evolution of CVD risk factors in young adults. The new analysis indicates that fiber consumption is independently and inversely associated with insulin levels, weight gain and other CVD risk factors among healthy, young black and white adults. A report of this analysis, "Dietary Fiber, Weight Gain, and Cardiovascular Disease Risk Factors in Young Adults," appears in the October 27, 1999 edition of the Journal of the American Medical Association (JAMA).
The CARDIA Study, a multi-center, population-based study, is following young black and white adults in four US areas: Birmingham, AL, Chicago, IL, Minneapolis, MN, and Oakland, CA. The new analysis looked at 2,909 of the CARDIA participants over the 10 years between 1985-1986 to 1995-1996. Its purpose was to examine the role of fiber compared to fat and other major dietary components in the development of hyperinsulinemia (an abnormally high level of insulin in the blood), obesity and other CVD risk factors (e.g. hypertension, high blood cholesterol). Insulin resistance and hyperinsulinemia are associated with many of these risk factors.
The health benefits of dietary fiber have been the subject of research interest for some time. Findings from this new study support the positive effects of diets high in fiber. The authors discuss how fiber may affect the risk of CVD. They note that dietary fiber slows the rate of nutrient absorption following a meal, and may reduce insulin secretion. This study's findings need to be confirmed in long-term interventional studies which more fully examine the relationship between dietary fiber, insulin levels, and CVD risk factors.