2010 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.
Objective 3: Develop a mathematical model relating blood glucose kinetics to whole body substrate oxidation.
Sub-objective 3.A.: Determine the effect of physical activity, gender and age on postprandial and 24-h substrate oxidation and glycemic control.
Sub-objective 3.B.: Develop predictive models and algorithms for existing ambulatory physiological monitoring systems to estimate real-time blood glucose and substrate oxidation based on continuous estimates of energy expenditure and duration and intensity of physical activity.
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. In an effort to better understand macronutrient metabolism, mathematical modeling techniques will be used to estimate substrate oxidation from glucose monitoring techniques. This research will fill knowledge gaps in macro and micronutrient metabolism and provide a scientific basis for dietary recommendations and nutrition policy.
Institutional Review Board approvals were received to study trans fatty acids from different dietary sources and the conversion of monomers of trans fatty acids to isomers of conjugated linoleic acids, a fatty acid with purported health benefits. A highly-controlled dietary intervention was conducted. A total of 119 participants were randomized and 95 completed the entire intervention. Each subject received one of four treatments consisting of:.
1)a base diet containing approximately 0.1% of energy as mixed trans fatty acid isomers (base diet),.
2)the base diet with 3.0% energy from vaccenic acid (18:1 trans-11, found naturally in dairy products),.
3)the base diet with 3.0% energy as mixed isomers of trans fatty acids from partially hydrogenated vegetable oil, and.
4)the base diet with 1.0% of energy from cis-9, trans-11 conjugated linoleic acid (converted from vaccenic acid by mammals; also called rumenic acid). Energy from trans fatty acids replaced energy from stearic acid so that all diets had a fat content of 33.6% of energy from fat, 17% of energy from protein, and the balance from carbohydrate. The length of feeding of each treatment was 24 days with blood sampling occurring on days 22 and 24 of each period.
Institutional Review Board approval was also obtained to investigate how different sources of protein affect risk factors for cardiovascular disease and diabetes, including blood pressure and insulin sensitivity. A double-blind, randomized, controlled-feeding study in 33 adults (22F, 11M; BMI 25-42 kg/m2, ages 28-70, blood pressure between 120/80 and 150/100 mm Hg) was conducted to compare the effects of a controlled, typical American diet supplemented with whey protein, soy protein, or maltodextrin (carbohydrate control) on inflammatory biomarkers. Participants consumed treatment powders reconstituted into beverages twice daily, at breakfast and dinner, for 4 weeks. Each participant consumed 40 g/d of either whey protein (n = 12), soy protein (n = 10), or carbohydrate (n = 11), as part of a weight-maintenance diet.
Analysis of the results of these studies is on-going.