Location: Food Components and Health Laboratory2017 Annual Report
Diet is a modifiable factor that can influence the multitude of chronic health disorders that face the U.S. adult population, including type 2 diabetes, cardiovascular disease, some cancers, arthritis, endothelial dysfunction, and others. Through the experiments planned for this project, we will attempt to improve the understanding of the influence of diet on chronic disease. We will investigate direct effects of diet on cardiometabolic profile and additionally factors that influence weight gain, which increases risk for chronic disease. Objective 1. Determine the energy content of specific foods in the context of a mixed diet, and the absorption, metabolism and impact on biomarkers for health promotion of these foods or their macro and micro components. Objective 2. Determine the influence and interaction of the composition of food intake and exercise on glucoregulation, cardiometabolic profile, and metabolic flexibility (fuel management). Objective 3. Determine the extent to which the day-to-day variation in daily voluntary food intake, measured over at least 3 months, is related to diet composition, physical activity, and changes in physiological and metabolic markers related to energy balance, satiety and hunger.
Diet is a modifiable lifestyle factor that can influence the multitude of chronic diseases faced by an increasing proportion of the U.S. population, including type 2 diabetes, hypertension, vascular dysfunction, cardiovascular disease, cancer, and arthritis. Moreover, the widespread global prevalence of these diseases threatens the quality of life and places additional stresses on an already overburdened health care system. This project, through highly controlled human feeding studies, will target specific factors which influence risk for and development of chronic disease. First, research will be conducted to improve accuracy of the energy value of foods, which can impact weight gain, a risk factor for chronic disease. Second, research will be conducted to investigate dietary factors that can influence cardiometabolic profile, i.e. risk for cardiovascular disease, stroke, or diabetes. Third, we will study how diet influences voluntary food intake, again impacting weight gain, a risk factor for chronic disease. The outcomes of this research will provide a better understanding of 1) the energy content of specific foods in the context of a mixed diet, and the absorption, metabolism and impact on biomarkers for health promotion of these foods or their components, 2) dietary and lifestyle influences on diabetes and cardiovascular disease risk, and 3) the extent to which the day-to-day variation in daily voluntary food intake is related to diet composition. This research will fill knowledge gaps in the metabolism of macro and micro food components related to the development and management of obesity and chronic diseases, and provide a scientific basis for dietary recommendations and nutrition policy.
Progress was made for both objectives of this project plan linked to National Program 107 Plan, focusing on Component 3 to provide a Scientific Basis for Dietary Guidance. Progress has been made addressing Problem Statement 3B: Identify Roles of Food, Food Components and Physical Activity in Promoting Health and Preventing Disease through studies on tree nuts and energy metabolism. Under Objective 1, two studies were completed. These studies were conducted to provide more accurate values for metabolizable energy of nuts. Metabolizable energy represents the energy available to the body, and accounts for energy losses in feces and urine, mostly associated with incomplete digestion of a food. Metabolizable energy is calculated as the difference in the gross energy of a food (measured using bomb calorimetry) and urine and fecal energy (also measured using bomb calorimetry). A study with almonds established how food processing (roasting, chopping and grinding) affects the metabolizable energy content of a serving of almonds. The metabolizable energy content of a 28 g serving of whole dry-roasted almonds is higher than that of whole natural almonds. Chopping roasted almonds and whole roasted almonds have similar metabolizable energy values. However, almond butter has a higher metabolizable energy value than whole or chopped almonds. Except for almond butter, all forms of almonds have a lower metabolizable energy value than what is currently listed on the food label for almonds. Gross energy of these different forms of almonds is similar – the measured differences are those of the metabolizable energy (accounting for incomplete digestion). Compared to unroasted almonds, the force needed to break apart roasted almonds is less, and roasting also results in a greater number of smaller particles being produced when the almond is broken. Thus, roasting almonds increases the brittleness of the almond, allowing them to break apart more easily and presumably increase digestibility. Additional research with cashews was completed. Research continues on investigating how new varieties of soybeans can reduce risk for cardiovascular disease and provide functional properties for frying, baking and sautéing. Soybean oil is an important oil for many food preparation processes. Because of its high (and healthful) polyunsaturated fatty acid content, it has a limited shelf-life. Certain food preparation processes, such as frying, further decrease the shelf-life of oils that contain high amounts of polyunsaturated fatty acids. Historically, partial hydrogenation has been used to increase shelf-life but the U.S. Food & Drug Administration has determined that partially hydrogenated oils are no longer “generally recognized as safe” due to the presence of trans fatty acids. Plant scientists have developed cultivars of high oleic soybean oil that have higher concentrations of monounsaturated fatty acids and lower concentration of polyunsaturated fatty acids. Oils from these soybeans are more shelf stable without the need of partial hydrogenation. In a large, randomized control, double-blind study, consumption of high-oleic soybean oil improved blood lipids compared to alternative oils with similar functional properties. A study investigating the Mediterranean dietary pattern was completed. The Mediterranean dietary pattern has gained widespread popularity because of an impressive evidence base showing health benefits in the prevention of many chronic diseases including CVD, diabetes, metabolic syndrome, and obesity. In this study, lean beef is being consumed at three levels of intake to determine if lean beef in a Mediterranean-style dietary pattern will provide similar cardioprotective benefits when compared to an average American diet. Sample analyses is underway. Under objective 2, research continues on metabolic fuel use (the burning of protein, fat or carbohydrate for energy). The modern-day lifestyle is characterized by a majority of time spent sitting throughout the day. Metabolic flexibility and glucose control decline progressively with aging; however, this can be attributed primarily to factors secondary to aging. Indeed, sedentary living is a challenge to metabolic control – especially in older age when insufficient insulin secretion and multi-tissue insulin resistance are also important contributors to impaired glucose control. Research was conducted investigating the effects of prolonged sitting and sedentary lifestyle, and whether minimal intensity walking can improve resistance to such dysregulation and improve metabolic fuel use.
1. The metabolizable energy content of almonds is lower than stated on food labels. The data used to determine the calorie content of almonds is over 100 years old. If these data are inaccurate, then food labels will not provide accurate information to consumers. Almonds are commonly consumed whole, roasted, chopped and as butter, and all of these forms use the same data for labeling their calorie content (which represents the metabolaizble energy fo the food, accounting for incompelte digestion). ARS researchers at the Beltsville Human Nutrition Research Center, Beltsville, Maryland, conducted a study to determine the accuracy of the food labeling data and the effect of food processing on almond metabolizable energy (calorie) content. Dry-roasting increases the metabolizable energy (calorie) content of almonds, and chopping and grinding to make almond butter also increases the metabolizable energy (calorie) content; however, except for butter, all forms of almonds have less metabolizable energy (fewer calories) than currently stated on food labels. The food industry is updating food labels so consumers will have more accurate information on the calorie content of their food.