2007 Annual Report
1a.Objectives (from AD-416)
To determine if black tea antioxidants reduce oxidative damage and inflammation, and improve endothelial function and lipoprotein profile in cigarette smokers, and to determine the relative antioxidant effect of caffeine and tea flavanoids, to determine acute effects of drinking green, oolong, and black tea and other sources of polyphenols on insulin sensitivity, plasma antioxidant status, plasma triglyceride concentration, and whole body cytokine response of diabetics following consumption of a moderately high glycemic meal, and to determine if longer-term consumption of green, oolong, and black tea and other sources of polyphenols improves plasma antioxidant status, cardiovascular disease risk factors and glucose metabolism for individuals at risk for type II diabetes (prediabetics).
1b.Approach (from AD-416)
Dietary intervention studies will be conducted with human volunteers who are increased risk for chronic, degenerative diseases, such as diabetes, cardiovascular disease, cancer and obesity. Dietary interventions will focus on sources of polyphenols that may decrease macromolecular and physiological oxidative stress and decrease inflammation.
This project focuses on Human Nutrition Program 107, component #3 (Diet, Genetics, Lifestyle, and the Prevention of Obesity and Disease) and component #7 (Health Promoting Properties of Plant and Animal Foods). Scientists in the Food Components and Health Laboratory have conducted two studies of polyphenols, one study of fiber, and one study of protein sources. A dietary intervention was completed investigating the relationship between polyphenols in cocoa and tea and their effect on insulin sensitivity, oxidative stress, and inflammation. In this study, individuals at risk for diabetes were provided different amounts or sources of polyphenols as part of a controlled diet. In a second study, individuals were provided different types of polyphenols from oolong tea. In this current study, insulin sensitivity, oxidation, oxidative stress, inflammation, and endothelial health are being measured. In addition, a dietary intervention study was designed to measure the effect of soluble fiber on nutrient absorption, microflora, and oxidation. Samples from this study are being analyzed.
Protein Intake and Risk Factors for Chronic Disease:
A dietary intervention study was completed in which volunteers consumed two sources of protein or carbohydrate at an equal level of energy: whey protein (found in milk), soy protein, and a complex carbohydrate daily over a period of 6 months to determine the effect of protein sources on body weight, body fat, markers of inflammation, and biomarkers of cardiovascular disease, diabetes, and obesity. There was a significant benefit of dietary protein supplementation with respect to body weight and fat. Protein intake also improved insulin response. These results suggest the dietary protein is associated with improving body composition, and that whey protein may help improve some risk factors for chronic diseases. This project falls under National Program 107 Component 3, “Diet, Genetics, Lifestyle, and the Prevention of Obesity and Disease” and Component 7, “Health Promoting Properties of Plant and Animal Foods."
5.Significant Activities that Support Special Target Populations
|Number of non-peer reviewed presentations and proceedings||9|
|Number of newspaper articles and other presentations for non-science audiences||5|
Stote, K.S., Baer, D.J., Spears, K., Paul, D.R., Rumpler, W.V., Strycula, P., Najjar, S.S., Ferrucci, L., Ingram, D.K., Longo, D.L., Mattson, M.P. 2007. A controlled trial of reduced meal frequency without caloric restriction in healthy, normal weight middle-aged men and women. American Journal of Clinical Nutrition. 85:981-988.
Mahabir, S., Baer, D.J., Johnson, L., Hartman, T., Dorgan, J., Campbell, W., Judd, J.T., Clevidence, B.A., Taylor, P. 2006. Usefulness of body mass index (BMI) as a sufficient adiposity measurement for sex hormone concentration associations in postmenopausal women. Cancer Epidemiology Biomarkers and Prevention. 15(12):2502-2507.