1a. Objectives (from AD-416)
LAB: ANTIOXIDANTS Objective 1. Identify and quantify the flavonoid content of: blueberries, cranberries, and grapes; almonds, pistachios, and walnuts; and cocoa-based foods and contribute to future updates of the USDA Database for the Flavonoid Content of Selected Foods. Objective 2. Determine tissue bioavailability and chemopreventive properties of anthocyanin-rich extracts of blueberries, cranberries, and grapes in a mouse model. Objective 3. Investigate the effect of age on quercetin bioavailability and metabolism due to changes in phase II enzyme activity. Objective 4. Test whether exposure of rat dams to a “Western” diet during pregnancy and lactation will increase obese phenotypes in their pups and whether dietary flavonoids, particularly isoflavones, will decrease the obese phenotype. LAB: CAROTENOIDS Objective 1: Determine the ability of bioactive plant-based foods, including carotenoid-rich foods to exert biological functions and affect genomic stability. Objective 2: Determine the vitamin A requirement of healthy U.S. adults.
1b. Approach (from AD-416)
LAB: ANTIOXIDANTS Using advanced chromatographic methods, we will measure the flavonoid content and evaluate the total antioxidant capacity of selected plant foods and the influence of geographical regions, agricultural practices, and processing and storage. We will also investigate the bioavailability and chemopreventive properties of flavonoids, particularly anthocyanins, from berry fruit in a mouse model by examining their actions to reduce oxidative stress, modulate cell signaling pathways, decrease inflammation, and promote phase II detoxification. A rat model as well as microsomes from various rat tissues will be utilized to determine the effect of age on quercetin bioavailability and metabolism due to changes in phase II enzyme activity. We will explore the possible fetal origins of chronic disease by feeding obesigenic diets to rat dams during pregnancy and lactation and examine the change in obese phenotypes in their pups and test whether dietary flavonoids, particularly isoflavones, will decrease this phenotype. Using healthy older adults, we will determine the bioavailability and distribution of cranberry anthocyanins to blood, urine, and feces. Employing volunteers with coronary heart disease, we will test the effect of almond consumption on biomarkers of oxidative stress, inflammation, and vascular reactivity. LAB: CAROTENOIDS By recruiting older adults (>60 yr, men and post-menopausal women) without and with metabolic syndrome to ingest bioactive plant foods or histidine dipeptide rich foods, we will measure plasma total antioxidant performance, plasma in vivo oxidative stress biomarkers, plasma water-soluble and fat-soluble antioxidants (carotenoids, tocopherol, ascorbic acid, and uric acid), plasma biomedical parameters to determine the ability of bioactive plant-based foods, including carotenoid-rich foods, to exert biological functions and affect genomic stability. Also, to explore a possible correlation between a change in serum apoE and a change in Macular Pigment (MP) density, we will measure HDL subpopulations by non-denaturing 2d gel electrophoresis, immuno-blotting, and image analysis. We will measure lipoproteins, antioxidative capacity, and markers of inflammation in order to better define the mechanism by which decreased body weight is associated with increased MP in humans. Using the stable isotope labeled vitamin A (labeled in three different levels, ^13 C_4 , ^13 C_8 , ^13 C_12 – retinyl acetate) and aphereses-autologues technique on human volunteers, we will measure the enrichment of these labeled retinols in human circulations and mathematical modeling to determine vitamin A bioavailability and the requirement of vitamin A through an intervention trial with various levels of vitamin A.
3. Progress Report
This project includes the work of two subordinate projects at the HNRCA funded through a Specific Cooperative Agreement with Tufts University. For further information and progress reports see 1950-51000-073-01S, Phytochemicals and Aging: Bioavailability, Metabolomics and Bioactivity, and 1950-51000-073-02S, Dietary Carotenoids, Retinoids and Bioactivates on Healthy Aging.
1. Food constituents other than antioxidants affect the results of "Total Antioxidant Capacity" assays. (LAB: ANTIOXIDANTS RESEARCH). Assays of Total Antioxidant Capacity (TAC) have been employed to rank or standardize foods and beverages for research and marketing purposes. However, the manner in which their ingredients impact TAC values has been little studied. ARS-funded researchers from Tufts University in Boston used four different TAC assays to test grape and pomegranate juices and found their different antioxidant constituents as well as sugars and organic acids and interactions between these components affected the assay results. Testing different concentrations of the same juice for TAC also resulted in different outcomes. Thus, without a careful understanding of these complex relationships within these assays, simple rankings of the TAC value of foods and beverages may be misleading, especially with regard to their potential impact on health.
2. Values from "Total Antioxidant Capacity" assays are subject to variation from dilution factors. (LAB: ANTIOXIDANTS RESEARCH). Flavonoids are antioxidants found in most plant foods. Consuming more flavonoids has been associated with a reduced risk of some forms of cancer and heart disease. However, little is known about whether aging influences the metabolism and potential health benefits of flavonoids. Using young, middle-aged, and old rats, ARS-funded researchers from Tufts University in Boston found that age affected the rate and type of metabolism of flavonoids in the gastrointestinal tract and liver. As the metabolism of flavonoids is important to determining their bioactivity, these findings suggest that different amounts of these nutrients might need to be consumed by people of different ages to achieve a health benefit.
3. Identification of major bioactive components in plant foods (Angel's plant leaves and black soybeans). (LAB: CAROTENOIDS AND HEALTH). Phytochemicals are compounds found in plant foods that have shown to have certain health benefits; however, the availability of phytochemicals in Angel’s plant leaves and black soybeans was unknown. In order to determine the ability of bioactive functional foods to exert biological functions and affect genomic stability, ARS-funded researchers from Tufts University in Boston, MA, have developed a database on phytochemicals in these functional plant foods using highly sensitive state-of-the-art methods (high resolution LC-MS and informatics approach) and determined stability of major phytochemicals in these plant foods. They also developed nutrition bars using these functional plant foods to be made available to the public and consumed conveniently. This will allow the public to easily incorporate more phytochemicals into their diet and benefit from their protective properties.
Botero, D., Ebbeling, C.B., Blumberg, J.B., Ribaya-Mercado, J.D., Creager, M.A., Swain, J.F., Feldman, H.A., Ludwig, D.S. 2009. Acute effects of dietary glycemic index on antioxidant capacity in nutrient-controlled feeding study. Obesity. 17(9):1664-1670.