Location: Food Components and Health Laboratory2011 Annual Report
1a. Objectives (from AD-416)
Objective 1: Investigate macronutrient modulation of biomarkers of chronic disease. Sub-objective 1.A.: Investigate the role of individual fatty acids (such as alphalinolenic, stearic, conjugated linoleic, and/or vaccenic acids) on markers of inflammation and oxidation related to chronic disease. Delineate their metabolic pathways. Sub-objective 1.B.: Determine the differential effects of protein sources and macronutrient profiles on post-prandial oxidation, oxidative stress, insulin signaling,and blood pressure regulation. Objective 2: Improve biomarkers and indicators of nutritional adequacy through investigation of micronutrient metabolism. Sub-objective 2.A.: Investigate the differential in vivo metabolism of various forms of micronutrients (such as tocopherol and/or folate) through mathematical modeling.
1b. Approach (from AD-416)
Appropriate macro- and micronutrient intake is fundamental to a diet that will maintain health and reduce risk of chronic, degenerative diseases. For many nutrients or classes of nutrients, qualitative and quantitative estimates of intake to maintain health are available. However, for other nutrients, where there are a variety of dietary sources, specific sources may offer additional health benefits as compared to others. Many observations of the health effects of specific sources of food are based on epidemiologic data and therefore do not provide an opportunity to show a cause and effect. For example, epidemiologic data suggest that there is no association between consumption of naturally occurring trans fatty acids and risk for coronary heart disease whereas trans fatty acids from partially hydrogenated vegetable sources do increase risk for coronary heart disease and death. Epidemiologic data suggest that a decrease in body weight is associated with low-fat dairy food consumption but identification of the specific component(s) (such as proteins) found in low-fat dairy foods that may be responsible for this effect is needed. This five-year project will investigate the effects of different sources of trans fatty acids and protein on risk factors associated with cardiovascular disease, and diabetes in humans and will assess the relative bioavailability of synthetic and natural sources of vitamin E in humans using mathematical modeling. This research will fill knowledge gaps in macro and micronutrient metabolism and provide a scientific basis for dietary recommendations and nutrition policy.
3. Progress Report
A highly-controlled dietary intervention of different sources of trans fatty acids was conducted, the samples were analyzed and the findings were reported to stakeholders. Briefly, the naturally occurring trans fatty acid isomer from ruminant animal products (vaccenic acid) raised LDL cholesterol in a quantitatively comparable manner as mixed trans fatty acid isomers from partially hydrogenated vegetable oils (PHVO) at 3% of energy intake. Vaccenic acid (VA) raises LDL cholesterol to a greater extent that PHVO. However, it was also observed that VA raises HDL cholesterol compared to the control diet whereas PHVO does not. The predominant animal-derived isomer of conjugated linoleic acid (cis-9, trans-11 conjugated linoleic acid) did not change LDL cholesterol compared to the control diet. Compared to the control diet, this isomer had little effect on lipoproteins. However, triacylglyceride concentration did increase after consumption of cis-9, trans-11 conjugated linoleic acid compared to the control diet. Analyses of the results of a highly controlled dietary intervention of different protein sources relevant significant effects of protein on blood pressure and these effects persistent over time. Little effect of protein source was observed on substrate oxidation.
1. Pistachio nuts contain less energy than previously thought. Accurate food labeling is important for consumer to make appropriate food choices especially for energy (calories). Previous methods of estimating the energy value of pistachio nuts resulted in an overestimation of their energy value. Using appropriate methods, ARS researchers at the Beltsville, MD Human Nutrition Research Center measured the energy value and found it to be 5% lower. This research finding has lead to a change in food label of pistachios. Of note is the fact the nuts are an good source of several key nutrients and nut consumption is linked to decreased risk of some disease but some consumers avoid nuts because of the perceived high calorie content.
2. Whey protein supplementation compared to carbohydrate resulted in a lower body weight and body fat in overweight and obese men and women. Obesity is pandemic and dietary interventions to help maintain a healthy body weight are essential. ARS researchers at the Beltsville, MD Human Nutrition Research Center demonstrated that whey protein reduced a hormone associated with hunger and volunteers lost body weight, fat and waist circumference after consuming supplemental whey protein compared to carbohydrate at the end of a 5 month study. This potential health benefit associated with whey protein has significant positive impact on the US dairy industries efforts to market whey internationally resulting in an increased demand for U.S. dairy ingredients.
Baer, D.J., Novotny Dura, J., Harris, K., Stote, K., Clevidence, B.A., Rumpler, W.V. 2010. Oolong tea does not improve glucose metabolism in non-diabetic adults. European Journal of Clinical Nutrition. 65:87-93.