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United States Department of Agriculture

Agricultural Research Service

Research Project: BIOAVAILABILITY AND HEALTH BENEFITS OF PHYTONUTRIENTS

Location: Food Components and Health Laboratory

2013 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:
Progress was made for both objectives of this NP 107 plan, focusing on Component II and III to provide a Scientific Basis for Dietary Guidance for Health Promotion and Disease Prevention and for the Prevention of Obesity and Related Diseases. Progress has been made addressing Problem Statement 2A: Identify Roles of Food, Nutrients, Food Components, and Physical Activity in Promoting Health and Preventing Disease through studies on garlic, blackberries, grapes, cranberry juice, and lettuce.

Blackberries contain compounds that may reduce risk of cancer by reducing DNA damage. A feeding intervention was conducted to investigate the effect of blackberries in humans. Three hours after consuming blackberries compared to gelatin (control), there was a decrease in urinary 8-oxo-7’8-dihydro-2’-deoxyguanosine (8-oxodG), a marker of DNA damage. After 6 days of consuming blackberries or gelatin, there was no difference in 8-oxodG. These findings demonstrate that blackberries may be effective protecting against short-term DNA damage but this effect appeared to disappear after six days.

Epidemiological data suggest that garlic intake is inversely associated with the progression of heart disease and cancer. We conducted a randomized crossover feeding trial in which 17 volunteers consumed a garlic-containing meal or a garlic-free control meal after 10 days of a controlled, garlic-free diet. Seven genes were found to be increased by garlic intake. The biological significance of these results is likely to be multifaceted.

Repeated dosing of grape polyphenols has been found to affect bioavailability and metabolism of catechin and epicatechin. In addition, obesity may influence intestinal function and xenobiotic metabolism, which could alter polyphenol bioavailability. An intervention was conducted with 12 adults who were either normal weight or obese. Relative bioavailability was greater for grape flavonoids on day 11 compared to day 1 for the normal weight but not the obese volunteers. This study suggests that that repeated dosing and body composition likely influences polyphenol bioavailability.

Cranberry juice is rich in a variety of phenolic compounds, including flavonoids. We conducted a randomized clinical trial to investigate the effect of daily consumption of a low calorie cranberry juice beverage on cardiovascular disease risk factors. After 8 weeks of cranberry juice beverage consumption, markers of systemic inflammation were lower compared to that after consumption of the placebo beverage. Incorporation of a low calorie cranberry juice beverage into the diet of healthy adults appears to reduce risk factors of cardiovascular disease.

Leaf lettuce cultivars representing both red and green lines were exposed to supplemental UV radiation in several different controlled environments using deep ultraviolet light-emitting diodes (DUV-LEDs). Treatments enhanced foliar accumulation of flavonoids but not phenolic acid esters. The most effective wavelength for all lines was about 290 nm, but growth inhibition at shorter wavelengths could interfere with the response at wavelengths shorter than 290 nm.


4.Accomplishments
1. Postharvest storage of store-bought strawberries was approximately doubled under home refrigerator conditions when the strawberries were exposed to continuous dim ultraviolet light using a novel method incorporating light-emitting diodes. Storage time was evaluated based on mold growth, dry and fresh weight, and phytochemical composition, including anthocyanins, soluble solids and titratable acidity. Data were used to support a patent application.


Review Publications
Hursel, R., Viechbauer, W., Dulloo, A.G., Tremblay, A., Tappy, L., Rumpler, W.V., Westerterp-Plantenga 2011. The effects of catechin rich teas and caffeine on energy expenditure and fat oxidation: a meta-analysis. Obesity Reviews. 12:e573-e581.

Charron, C.S., Clevidence, B.A., Albaugh, G.P., Milner, J., Novotny Dura, J. 2012. Assessment of DNA damage and repair in adults consuming allyl isothiocyanate or Brassica vegetables. Journal of Nutritional Biochemistry. 24:894-902.

Novotny Dura, J., Baer, D.J., Chen, K., Gonzalo, R., Kim, S., Holstege, D., Owens, J., Liu, B., Muller, H., Medrano, J., Fadel, J., Clifford, A., Mcwade, L., Moshfegh, A.J. 2012. Gender and single nucleotide polymorphisms in MTHFR, BHMT, SPTLC1, CRBP2, and SCARB1 are significant predictors of plasma homocysteine normalized by RBC folate in healthy adults. Journal of Nutrition. 142:1764-1771.

Last Modified: 7/31/2014
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