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ARS Home » Northeast Area » Beltsville, Maryland (BHNRC) » Beltsville Human Nutrition Research Center » Food Components and Health Laboratory » Research » Research Project #415242


Location: Food Components and Health Laboratory

2010 Annual Report

1a. Objectives (from AD-416)
Objective 1: Elucidate factors which influence bioavailability, metabolism, and kinetics of dietary phytonutrients, such as anthocyanins, ellagitannins, flavonoids, allylic sulfides, and isoflavones, and define the observed inter-individual variation as well as the genetic basis for the observed variation. Sub-objective 1.A: Characterize effects of postharvest processing on phytonutrient content. Sub-objective 1.B.: Determine the importance of aglycone structure on anthocyanin bioavailability. Sub-objective 1.C.: Determine the importance of acylation on anthocyanin bioavailability. Sub-objective 1.D.: Determine the influence of protein on anthocyanin bioavailability. Sub-objective 1.E.: Identify metabolites of anthocyanins. Sub-objective 1.F.: Develop methods to isotopically label quercetin in leaf lettuce. Sub-objective 1.G.: Identify metabolites of quercetin. Sub-objective 1.H.: Develop methods to isotopically label isoflavones in soy. Objective 2: Determine the ability of plant-based dietary components to influence oxidative stress, inflammation, DNA damage, glucoregulation, and blood pressure, and define the inter-individual variation in these responses as well as the genetic basis for the variation. Sub-objective 2.A.: Determine the effect of pomegranate juice on blood pressure, endothelial function, and inflammation. Sub-objective 2.B.: Discover mechanisms by which garlic phytonutrients affect risk factors for cancer and cardiovascular disease.

1b. Approach (from AD-416)
Epidemiological studies have repeatedly shown that diets high in fruits and vegetables are associated with decreased risk of chronic diseases that ultimately strike most Americans. However, the scientific foundation necessary to translate these epidemiological findings into dietary recommendations is weak. Research is needed to clarify specific health benefits of phytonutrients, to determine their bioavailability, to delineate rates of metabolism and elimination from the body, and to identify genetic differences among individuals that impact phytonutrient action in the body. This plan describes a five-year research project to investigate content, bioavailability, metabolism, and health benefits of selected phytonutrients. Studies will be conducted to determine the effect of postharvest processing on phytonutrient content. The initial focus of the postharvest studies will be leaf lettuce and tomatoes, and these studies will be expanded to include kale, spinach, swiss chard, and strawberries as funding is available. Several studies will be conducted to improve understanding of phytonutrient bioavailability and metabolism. The proposed focus of these studies is anthocyanins, building on previous work in our lab. Methods will be developed to isotopically label quercetin in lettuce and isoflavones in soy. These studies will expand our isotopic labeling program from carotenoids and anthocyanins to other phytonutrients. The influence of phytonutrients on biomarkers of chronic disease will be investigated, with an initial focus on garlic due to its promising role in cancer prevention. Genotyping will be included in clinical studies whenever sufficient scientific justification exists. This research will be conducted through plant growth and postharvest studies, human feeding trials, quantitative and qualitative chemistry, molecular biology, and kinetic mathematical modeling techniques. Information generated from this project can be used to develop recommendations for dietary intakes of phytonutrients that will improve health and reduce risk of chronic disease.

3. Progress Report
This is a project through which investigations into the health benefits of phytonutrients in humans are being conducted. Over the past year, new laboratory methods have been developed to analyze metabolites of anthocyanins (antioxidant pigments found in plant foods). In addition, three Institutional Review Board protocols have been submitted and approved. One protocol addresses anthocyanin bioavailability, one protocol addresses anthocyanins and heart disease risk, and one protocol addresses garlic and risk for chronic disease. Recruitment for the two anthocyanin studies is underway. Recruitment for the garlic study is complete and the intervention period is underway. Ultraviolet light experiments on enhancement of flavonoids in leaf lettuce showed about a 2.5 fold increase in quercetin-3-malonyl glucoside and cyanidin 3-malonyl glucoside after 48 hours of treatment. Potential labeling conditions were identified that produced 1.6 mg quercetin for 100 g fresh weight leaf lettuce.

4. Accomplishments