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United States Department of Agriculture

Agricultural Research Service

Related Topics

Research Project: Linking Foods, Behavior and Metabolism to Promote a Healthy Body Weight

Location: Obesity and Metabolism Research Unit

2012 Annual Report


4.Accomplishments
1. Unique neural-adipocyte genes. Synuclein gamma (SNCG) is a factor uniquely expressed in both fat cells and peripheral neurons that sense temperature, pain, and other signals. In collaborative work with ARS scientists, it was discovered that mice lacking SNCG display an altered metabolic response to high-fat diet-induced obesity. This suggests that some lipid-modifying, obesity-regulated genes found in fat cells, also present in peripheral nerves, could integrate environmental and dietary cues with the brain. This integration is critical to establishing metabolic health through its impact on whole-body physiology.

2. Intermediary metabolism of sugar & fats. Blood metabolite analyses pointed to perturbed amino acid metabolism in obese insulin-resistant and diabetic states. Also, enzymes associated with select amino acid breakdown were found to be significantly reduced in the fat of obese individuals. Some protein-derived blood metabolites tracked status of gut bacterial populations, highlighting the importance of non-self gut organisms and diet in driving systemic metabolism of amino acids in the obese state. This suggests that inefficient fat tissue amino acid breakdown for energy, and changes in the gut microbe signature, underlie health phenotypes in response to diet.

3. Food choices in children. Poor development of decision-making skills early in life may increase risk for emotional-based food choices later in life. In preschoolers, greater palatable snack food intake was associated with poor inhibitory control. Eating in the absence of hunger was also associated with emotional arousal measured by skin conductance and salivary hormones. Thus, even in very young children a shift from executive to more emotional decision-making may promote excess calorie consumption.

4. Breakfast and insulin action. Regular breakfast consumption is linked to better health outcomes across the population. The specific health benefits of eating breakfast have remained elusive. It was found that individuals who skipped breakfast consistently were more insulin-resistant than their breakfast-eating counterparts. This demonstrates that habitually omitting breakfast is related to compromised insulin action, a risk factor for type 2 diabetes and impaired blood sugar regulation.

5. Omega-3 fatty acid recommendations. A diet rich in long chain omega-3 fatty acids is associated with reduced risk for cardiovascular disease, and recommended intake of fatty fish are based on this health benefit. The efficiency of omega-3 fatty acid consumption in regulating changes in beneficial lipids in blood components were found to decrease as a person’s omega-3 fatty acid status reached the levels associated with this health benefit. Based on the small study performed, current dietary recommendations appear to be in the right range to maintain a healthful omega-3 status for an average sized individual. However, individual recommendations would be improved by accounting for differences in body weight.

6. Development of bioinformatics tool. New technologies generate a large amount of information about physiological functions, genetics, and metabolism. High information content data analysis is a critical component of modern biological research. A new open source software package was developed allowing access to the statistical power of R within a user-friendly Microsoft Excel environment. The software has been made free to download on the internet and has been accessed over 2,000 times by the public.

7. Lipid phenotyping to assess metabolic health. Obesity and type 2 diabetes are often coincident conditions making the segregation of their metabolic consequences difficult. In a study comparing overweight African-American women with and without type 2 diabetes, it was discovered that independent of weight, diabetes elevated blood plasma free fatty acids, increased markers of hepatic lipogenesis, decreased markers of very long chain fatty acids synthesis and altered specific classes of endocannabinoid metabolites. These findings demonstrate the usefulness of “lipidomics” which involves the analysis of a broad spectrum of lipid-soluble compounds circulating in blood. The application of “lipidomics” provides a means to directly assess the metabolic health of overweight individuals, going beyond the traditional determination of blood glucose alone.

8. Zinc and blood glucose control. Although type 2 diabetes is often associated with obesity, it can occur in lean subjects. Possible links to diabetes in lean individuals may be poor nutritional status, including imbalanced micronutrient metabolism. A mouse model was developed that lacks a key zinc transporter, and this led to poor blood sugar control in the mice despite that they remained lean on a high fat diet. The study revealed that zinc, an essential micronutrient, is an important player in maintaining normal secretion and function of the blood glucose-regulating hormone insulin.

9. Zinc and glucose uptake in muscle. Muscle tissue requires a constant source of energy, including glucose, to function optimally. Micronutrient status may impinge upon pathways involved in tissue glucose uptake. A rat skeletal muscle cell line with enhanced zinc transporter proteins was developed to test this concept. The results demonstrated that the zinc transporter ZnT7 has an insulin-sensitizing effect leading to increased glucose uptake in muscle.


Review Publications
Adams, S.H. 2011. Emerging perspectives on essential amino acid metabolism in obesity and the insulin-resistant states 1,2. Advances in Nutrition. doi:10.3945.

Laugero, K.D., Tryon, M.S. 2011. Stress and food intake: What's the deal with your meal?. CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources. doi: 10.1079/PAVSNNR20116034.

Krishnan, S., Newman, J.W., Hembrooke, T.A., Keim, N.L. 2012. Variation in metabolic responses to meal challenges differing in glycemic index in healthy women: Is it meaningful?. Journal of Nutrition and Metabolism. 9(1):26.

Cox, C., Stanhope, K.L., Schwarz, J.M., Graham, J.L., Havel, P.J., Keim, N.L. 2011. Consumption of fructose-sweetened beverages for 10 weeks reduces net fat oxidation and energy expenditure in overweight/obese men and women. American Journal of Clinical Nutrition. Eur J Clin Nutr. 2012 Feb;66(2):201-8.

Banna, J.C., Keim, N.L., Townsend, M.S. 2011. Assessing face validity of a physical activity questionnaire for Spanish-speaking women in California. Journal of Extension. Vol.49:5.

Thomas, A.P., Dunn, T.N., Drayton, J.B., Oort, P.J., Adams, S.H. 2012. A high calcium diet containing nonfat dry milk reduces weight gain and associated adipose tissue inflammation in diet-induced obsed mice when comparated to high calcium alone. Nutrition and Metabolism. 9:3.

Hirahatake, K.M., Meissen, J., Fiehn, O., Adams, S.H. 2011. Comparative effects of fructose and glucose on lipogenic gene expression and intermediary metabolism in HepG2 liver cells. PLoS One. 10.1371.

Viscarra, J.A., Vazquez-Medina, J.P., Rodriguez, R., Champagne, C.D., Adams, S.H., Crocker, D.E., Ortiz, R.M. 2012. Decreased expression of adipose CD36 and FATP1 are associated with increased plasma nonesterified fatty acids during prolonged fasting in northern elephant seal pups (Mirounga angustirostris) . Experimental Biology. 215(Pt 14):2455-64.

Huang, S., Rutkowsky, J.M., Snodgrass, R.G., Ono-Moore, K., Schneider, D.A., Newman, J.W., Adams, S.H., Hwang, D.H. 2012. Saturated fatty acids activate TLR-mediated pro-inflammatory signaling pathways. Journal of Lipid Research. Epublished. DOI: 10.1194/jlr.D029546.

Grapov, D., Newman, J.W. 2012. imDEV: a graphical user interface to R multivariate analysis tools in Microsoft Excel. Oxford University Press. doi:10.1093.

Keenan, A.H., Pedersen, T.L., Fillaus, K., Larson, M.K., Shearer, G.C., Newman, J.W. 2012. Basal omega-3 fatty acid status affects fatty acid and oxylipin responses to high-dose n3-HUFA in healthy volunteers. Journal of Lipid Research. doi: 10.1194.

Last Modified: 9/1/2014
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