2008 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.
In FY 08 three human studies were completed. One study was to determine the effect of different types of tea polyphenols on insulin sensitivity, inflammation and antioxidant status; data from this study have been submitted for publication. A second study was undertaken to collect additional information on tea polyphenols and insulin sensitivity: specifically to compare data collected on black tea polyphenols with those from oolong tea. In this study, the acute effects of different tea polyphenols (i.e., simple catechins such as those found in green tea, theaflavins such as those found in oolong tea, and thearubigins such as those found in black tea) were studied, investigating the effects on inflammation, oxidative status, and insulin sensitivity. During FY 08 samples and statistical analyses were completed from this study. The third study, an intervention study of resistant maltodextrin, continued research on the relationship between macronutrient sources and their effects on body composition. During FY 08 research on protein sources and body composition were submitted for publication. These studies are providing new information about how dietary manipulations affect insulin sensitivity and risk for cardiovascular disease.
This research focuses on all three areas of the Human Nutrition Program 107. These include component #3 (Diet, Genetics, Lifestyle, and the Prevention of Obesity and Disease), component #6 (Health Promoting Intervention Strategies for Targeted Populations), and component #7 (Health Promoting Properties of Plant and Animal Foods).
5.Significant Activities that Support Special Target Populations
Carlson, O., Martin, B., Stote, K.S., Golden, E., Maudsley, S., Najjar, S.S., Ferrucci, L., Ingram, D.K., Longo, D.L., Rumpler, W.V., Baer, D.J., Egan, J., Mattson, M.P. 2007. Impact of reduced meal frequency without caloric restriction on glucose regulation in healthy, normal weight middle-aged men and women. Metabolism. 56:1729-1734.