Over the past 20 y dietary fiber has emerged as a leading dietary factor in the prevention and treatment of chronic diseases. High fiber intakes are associated with lower serum cholesterol concentrations, lower risk of coronary heart disease, reduced blood pressure, enhanced weight control, better glycemic control, reduced risk of certain forms of cancer, and improved gastrointestinal function. Dietary fiber can be categorized into water-soluble and water-insoluble components. Dried beans, oat products, and certain fruits and vegetables are good sources of soluble fiber. Most plant foods are good sources of insoluble fiber and wheat bran is a concentrated form of insoluble fiber. Current guidelines advise a doubling of dietary fiber intake for Americans. Inclusion of ample servings of fruits and vegetables, whole grains, and dried beans and peas will help individuals meet these guidelines.

Dried beans lower serum lipid concentrations in healthy and hyperlipidemic subjects. To determine the effects of canned beans on serum lipid concentrations, 24 hyperlipidemic men ate one of three bean diets for 21 d in a metabolic ward. Diets A and B included 227 g canned beans (120 g beans with 107 g tomato sauce) daily, in a single dose for diet A and in a divided dose for diet B. Diet C included 182 g canned beans (162 g beans with 20 g tomato sauce) daily in a divided dose. All bean diets combined lowered serum cholesterol and triglyceride concentrations 10.4% (p less than 0.001) and 10.8% (p less than 0.025), respectively. Diet B was as effective as diet C, and the groups on those diets had greater cholesterol reductions than did the group on diet A. Serum cholesterol reduction was positively correlated (p less than 0.01) with intake of total dietary fiber and soluble fiber. The ratios of low- to high-density-lipoprotein cholesterol remained constant for all groups. Body weight decreased 1.0-1.5 kg for all groups despite constant energy intakes. Canned beans may make an important contribution to hyperlipidemia management.

With new diabetes diet guidelines recommending high carbohydrate intake, questions arise regarding acceptable intake of simple sugars. Whereas several short-term studies report flattened glycemic and insulin response to fructose consumption, some also report increased serum triglyceride levels. Few studies examine the effects of long-term fructose consumption. We evaluated the long-term safety of fructose consumption in 14 middle-aged men with diabetes. Subjects followed an ambulatory high-fiber high-carbohydrate control diet at home for 8 wk, entered the hospital for 5 days on this diet, and spent the next 7 days on a similar diet supplemented with 50-60 g fructose. They continued the fructose diet at home for 23 wk, then resumed a postcontrol diet for an additional 16 wk. In the hospital, glycemic control improved significantly on the fructose-supplemented diet compared with the hospital control diet. In the ambulatory setting, no significant differences in plasma glucose, glycohemoglobin, serum cholesterol, triglycerides, lactate, or urate occurred between precontrol, fructose, or postcontrol periods. Fasting serum lactate was higher by 0.5 meq/L during the ambulatory fructose period than during the precontrol period. Body weight also increased during the ambulatory fructose period due to higher calorie intake. Adherence to fructose consumption was excellent and improved adherence to carbohydrate and fat recommendations. If total calorie intake is controlled to promote desirable body weight, crystalline fructose used with a high-carbohydrate high-fiber low-fat diet appears to be safe and acceptable for diabetic individuals.

Oat and bean products, which contain large amounts of water-soluble fiber, are particularly effective hypocholesterolemic agents. Recent experiments with human subjects using these products as supplements to the diet are reviewed. High-carbohydrate, high-fiber diets offer a nutritious, economical, and readily accepted means to reduce serum cholesterol.

Both food-containing and supplement diets providing 800 kcal a day effectively promote weight loss for obese individuals with NIDDM.