Location: Food Components and Health Laboratory
2016 Annual Report
Objectives
Diet is a lifestyle factor that is fairly easy to change and can have a significant impact on health. The human diet contains thousands of bioactive food components which have a multitude of physiologic actions, some of which can interrupt processes in the development of a host of chronic diseases. The goal of this project plan is to enhance the understanding of biological actions of food-based bioactive compounds to improve their efficacy in promoting health and preventing disease. We have organized the research team to broadly address the main factors affecting health benefits of dietary bioactive compounds: how much is in the food (content), how much we absorb from the food and how well we retain it (bioavailability/metabolism/elimination), and how the bioactive compounds work in the body (mechanisms of action). With respect to content, we intend to address agricultural practices that impact the amount of bioactive compounds present in crops and how to extend the shelf life of agricultural products. With respect to bioavailability, metabolism, and elimination, we intend to study both phenotypic and genotypic characteristics of individuals that impact the body’s nutrient handling. With respect to mechanisms of action, we will address reduction of risk for cancer, as well as other obesity related diseases. Bioactive compounds will include polyphenols, carotenoids, and sulfur compounds, because all demonstrate promising health benefits, and work with these compounds capitalizes on previous progress in our laboratory.
Objective 1. Delineate bioavailability, pathways of metabolism, and rates of elimination of bioactive substances from common foods (e.g., polyphenols, sulfur compounds, and other compounds as appropriate), and identify characteristics of humans that influence the body’s utilization of those bioactive substances.
Objective 2. Determine the impact of bioactive substances from common foods (e.g., polyphenols, sulfur compounds, and other compounds as appropriate) on markers of cancer risk in human and cell models.
Objective 3. Elucidate efficacy of bioactive substances from common foods (e.g. polyphenols, sulfur compounds, and other compounds as appropriate) on risk factors for diseases related to obesity.
Objective 4. Determine the impact of food composition heterogeneity (as influenced by genetics, environment, and agricultural production) on the variability in response of biomarkers of chronic disease to consumption of specific bioactive substances and its interaction with an individual’s nutrigenomic profile.
Objective 5. Determine the impact of agriculture, food production, and post-harvest practices on bioactive component content and variability, nutrient-nutrient interactions, and shelf life, with emphasis on fruits and vegetables.
Approach
Epidemiological studies have shown that diets high in fruits and vegetables are associated with decreased risk of chronic diseases. However, the scientific foundation necessary to translate these epidemiological findings into dietary recommendations is weak. 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/or strawberries. Several studies will be conducted on phytonutrient (anthocyanins) bioavailability and metabolism. Methods will be developed to isotopically label quercetin in lettuce and isoflavones in soy. The influence of phytonutrients on biomarkers of chronic disease will be investigated, with an initial focus on phytonutrients found in garlic due to possible roles 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.
Progress Report
Progress was made for objectives of this National Program 107 plan, which focuses on Component 3 to provide a Scientific Basis for Dietary Guidance. Progress has been made addressing Problem Statement 1A (Determine Agricultural Practices that Influence the Nutritional Status of Americans), 3A (Improve the Scientific Basis for Updating National Dietary Standards and Guidelines), 3B (Identify Roles of Food, Food Components and Physical Activity in Promoting Health and Preventing Disease), and 4A (Understand the Causes and Effects of Obesity and Obesity-Related Disorders) through studies on polyphenol availability in lean and obese individuals.
With the continuing rise in obesity come increases in many chronic diseases. Consumption of dietary bioactives, such as polyphenols, provides protection against multiple chronic diseases associated with obesity. However, polyphenol bioavailability appears to differ dramatically in at-risk obese compared to healthy individuals, and long term exposure appears to further influence bioavailability, a difference likely in part related to gut health.
The continued apparent beneficial effects of carotenoids and their metabolites on cancer processes, and their inverse association with cancer risk justify further studies to determine how and when carotenoids may be cancer preventative. Four recent studies have demonstrated an association between dietary carotenoid intake or plasma/serum carotenoid levels and decreased cancer incidence. However, some large intervention studies have suggested carotenoid intake may actually increase cancer risk. The difference in biological effects of carotenoids may be associated with differential formation of metabolites called apo-carotenoids and apo-lycopenoids, which can bind to nuclear receptors. Since methodology for measuring apo-carotenoids and apo-lycopenoids in blood have just recently been developed, very little is known about circulating levels of these compounds. A human intervention study was conducted to determine circulating levels of carotenoid metabolites after consumption of high carotenoid tomato juice. Using tomato cultivars developed by ARS scientists that contain high concentrations of either beta-carotene or lycopene, a six-week intervention study was conducted with thirty-six volunteers. As part of a controlled diet, participants consumed one of three beverages: placebo beverage (control), high beta-carotene tomato juice, and high-lycopene tomato juice. Blood, urine and feces were collected and analyses are ongoing.
A clinical intervention study is being conducted to investigate the effect of blackberries, a rich source of anthocyanin polyphenols, on the body’s fuel management (oxidation of protein, fat and carbohydrate for energy). The most recent statistics from the World Health Organization show that 1.5 billion adults are overweight, with 500 million of these adults being classified as obese. Worldwide, obesity has more than doubled in the last 30 years. The aim of this work is to seek dietary influences that can alter the body’s fuel management to reduce body fatness. Berries are a rich source of flavonoids, especially the bright pigments called anthocyanins. Animal studies have suggested that berry preparations or anthocyanin-rich berry extracts can reduce body fatness in animal studies, but human studies are lacking. The ongoing study is a randomized cross-over intervention with two 1-week controlled feeding periods. All volunteers consume the same base diet, with the treatment food or control food item being the only difference. The treatment food is blackberries daily or a calorie & fiber matched control food. Rates of protein, fat and carbohydrate oxidation are measured using respiratory-exchange calorimetry conducted in room-size calorimeters for a 24 hour period, and biochemical indicators of metabolism are being measured in the blood.
Accomplishments
1. Garlic consumption in humans activates genes associated with immune function and with decreasing cancer risk. Animal and epidemiological studies suggest that garlic intake is inversely associated with the progression of cancer and cardiovascular disease, whereas human study results have been ambiguous. One of the problems may be that the biomarkers used to measure risk for disease are not closely enough linked to disease outcome. ARS researchers at the Beltsville Human Nutrition Research Center, Beltsville, Maryland, showed how the body responds to garlic consumption by probing the deepest physiologic response, gene expression, focusing on pathways that affect cancer and cardiovascular disease. The data indicate that the bioactivity of garlic is multifaceted and includes activation of genes related to immunity, apoptosis (a cancer related process), and xenobiotic metabolism. These results will be useful to scientists who study the role of diet in cancer prevention and policy makers involved in making dietary recommendations to reduce risk for cancer and other chronic diseases.
2. Consumption of low calorie cranberry juice improves several risk factors for cardiometabolic health. Cardiometabolic risk is the risk for cardiovascular disease, diabetes, or stroke, which are leading causes of mortality and morbidity worldwide. ARS researchers at the Beltsville Human Nutrition Research Center, Beltsville, Maryland, conducted a double-blind, placebo controlled study to determine the effect of daily consumption of low calorie cranberry juice on cardiometabolic health. An important marker of inflammation (c-reactive protein), triglycerides, blood sugar, and diastolic blood pressure were lowered after consumption of low-calorie cranberry juice compared to the placebo (a flavor, color, and calorie matched beverage). These results demonstrate that juices prepared from polyphenol-rich berries can lower risk for cardiometabolic diseases. These results are of interest to food manufacturers, public health scientists formulating dietary guidance, dieticians, and consumers.
Review Publications
Moran, N.E., Cichon, M., Riedl, K., Grainger, E., Schwartz, S., Novotny Dura, J., Erdman, J., Clinton, S. 2015. Compartmental and noncompartmental modeling of 13C-lycopene absorption, isomerization, and distribution kinetics in healthy adults. American Journal of Clinical Nutrition. 102:1436-1449.
Charron, C.S., Dawson, H.D., Albaugh, G.P., Solverson, P.M., Vinyard, B.T., Solano Aguilar, G., Molokin, A., Novotny Dura, J. 2015. A single meal containing raw, crushed garlic influences expression of immunity- and cancer-related genes in whole blood of humans. Journal of Nutrition. 145:2448-2455.
Moran, N.E., Novotny Dura, J., Cichon, M., Riedl, K., Rogers, R., Grainger, E., Schwartz, S., Erdman, J., Clinton, S. 2016. Absorption and distribution kinetics of the 13C-labeled tomato carotenoid phytoene in healthy adults. Journal of Nutrition. 146:368-376.
