Interest has been recently rekindled in short chain fatty acids (SCFAs) with the emergence of prebiotics and probiotics aimed at improving colonic and systemic health. Dietary carbohydrates, specifically resistant starches and dietary fiber, are substrates for fermentation that produce SCFAs, primarily acetate, propionate, and butyrate, as end products. The rate and amount of SCFA production depends on the species and amounts of microflora present in the colon, the substrate source and gut transit time. SCFAs are readily absorbed. Butyrate is the major energy source for colonocytes. Propionate is largely taken up by the liver. Acetate enters the peripheral circulation to be metabolized by peripheral tissues. Specific SCFA may reduce the risk of developing gastrointestinal disorders, cancer, and cardiovascular disease. Acetate is the principal SCFA in the colon, and after absorption it has been shown to increase cholesterol synthesis. However, propionate, a gluconeogenerator, has been shown to inhibit cholesterol synthesis. Therefore, substrates that can decrease the acetate: propionate ratio may reduce serum lipids and possibly cardiovascular disease risk. Butyrate has been studied for its role in nourishing the colonic mucosa and in the prevention of cancer of the colon, by promoting cell differentiation, cell-cycle arrest and apoptosis of transformed colonocytes; inhibiting the enzyme histone deacetylase and decreasing the transformation of primary to secondary bile acids as a result of colonic acidification. Therefore, a greater increase in SCFA production and potentially a greater delivery of SCFA, specifically butyrate, to the distal colon may result in a protective effect. Butyrate irrigation (enema) has also been suggested in the treatment of colitis. More human studies are now needed, especially, given the diverse nature of carbohydrate substrates and the SCFA patterns resulting from their fermentation. Short-term and long-term human studies are particularly required on SCFAs in relation to markers of cancer risk. These studies will be key to the success of dietary recommendations to maximize colonic disease prevention.

The glycemic index concept is an extension of the fiber hypothesis, suggesting that fiber consumption reduces the rate of nutrient influx from the gut. The glycemic index has particular relevance to those chronic Western diseases associated with central obesity and insulin resistance. Early studies showed that starchy carbohydrate foods have very different effects on postprandial blood glucose and insulin responses in healthy and diabetic subjects, depending on the rate of digestion. A range of factors associated with food consumption was later shown to alter the rate of glucose absorption and subsequent glycemia and insulinemia. At this stage, systematic documentation of the differences that exist among carbohydrate foods was considered essential. The resulting glycemic index classification of foods provided a numeric physiologic classification of relevant carbohydrate foods in the prevention and treatment of diseases such as diabetes. Since then, low-glycemic-index diets have been shown to lower urinary C-peptide excretion in healthy subjects, improve glycemic control in diabetic subjects, and reduce serum lipids in hyperlipidemic subjects. Furthermore, consumption of low-glycemicindex diets has been associated with higher HDL-cholesterol concentrations and, in large cohort studies, with decreased risk of developing diabetes and cardiovascular disease. Case-control studies have also shown positive associations between dietary glycemic index and the risk of colon and breast cancers. Despite inconsistencies in the data, sufficient, positive findings have emerged to suggest that the dietary glycemic index is of potential importance in the treatment and prevention of chronic diseases.

Given the high prevalence of diabetes and pre-diabetes worldwide and the consistency of the scientific evidence reviewed, the expert panel confirmed an urgent need to communicate information on GI and GL to the general public and health professionals, through channels such as national dietary guidelines, food composition tables and food labels.

OST DIETARY MANIPULAtions result in modest cholesterol reductions of 4% to 13%, 1-10 and diet has been considered by some as a relatively ineffective therapy. 11 In contrast, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) repeatedly have been shown to reduce mean serum low-density lipoprotein cholesterol (LDL-C) concentrations by 28% to 35% in long-term trials, [12][13][14] with corresponding reductions in cardiovascular death of 23% to 32% in both primary and secondary prevention trials. 13,14 Recently, to boost effectiveness of diet for primary prevention of cardiovascular disease, the Adult Treatment Panel (ATP III) of the National Cholesterol Education Program has recommended addition of plant sterols (2 g/d) and viscous fibers (10-25 g/d) to the diet. 15 The American Heart Association has also drawn atten-Author Affiliations and Financial Disclosures are listed at the end of this article.

The cell walls of almond seeds reduce lipid bioaccessibility by hindering the release of lipid available for digestion.

Obesity is a major risk factor for development of diabetes, and excessive energy intake is a major contributor to poor glycemic control in Type 2 diabetes. The impact of obesity on risk for diabetes as well as coronary heart disease (CHD) risk factors and the benefits of weight loss in decreasing risk for developing diabetes and improving glycemia and CHD risks were reviewed. A systematic review of the medical literature to assess the impact of obesity and weight gain on risk for diabetes and CHD was done. We performed a meta-analysis of the effects of weight loss for obese diabetic individuals. Controlled clinical trials assessing lifestyle changes on risk for developing diabetes and weight loss effects on glycemia and CHD risk factors were reviewed. Obesity and weight gain can increase risk for diabetes by greater than ninetyfold and CHD by about sixfold. Very-low-energy diets (VLED) decrease fasting plasma glucose values by approximately 50% within two weeks and these changes are sustained with continued energy restriction. Twelve weeks of energy-restricted diets were associated with these significant decreases: body weight, 9.6%; fasting plasma glucose, 25.7%; serum cholesterol, 9.2%; serum triglycerides, 26.7%; systolic blood pressure, 8.1%; and diastolic blood pressure, 8.6%. Larger weight losses were associated with larger reductions in these values. The reviewed data suggest that US health care providers should endorse the American Heart Association's and European diabetes associations' recommendations that diabetic persons achieve and maintain a BMI of

In patients with type 2 diabetes, 6-month treatment with a low-glycemic index diet resulted in moderately lower HbA(1c) levels compared with a high-cereal fiber diet. Trial Registration clinicaltrials.gov identifier: NCT00438698.

No abstract