Project : USDA ARS

ARS Home » Pacific West Area » Davis, California » Western Human Nutrition Research Center » Obesity and Metabolism Research » Research » Research Project #436165

Research Project: Improving Public Health by Understanding Metabolic and Bio-Behavioral Effects of Following Recommendations in the Dietary Guidelines for Americans

Location: Obesity and Metabolism Research

2020 Annual Report

Accomplishments
1. Benefits of lower sodium and more vegetables in a whole food diet based on the Dietary Guidelines for Americans. Psychological stress is a growing public health concern. Nutritional habits may affect vulnerability or resilience to stress-related disease risk. Stress and how one reacts to stress are linked to increased risk for developing chronic diseases, such as diabetes, cardiovascular diseases, and neurological conditions and diseases. However, the factors that connect increased stress and disease risk remain unknown. In an eight-week randomized control trial that compared effects of a healthy Dietary Guidelines for Americans (DGA)-based diet and a relatively unhealthy diet (based on the typical American diet), ARS researchers in Davis, California, learned that adopting and adhering to a diet of higher quality (DGA) for eight weeks was shown to be generally more stressful in the absence of improvements in vegetable or sodium consumption. These study findings, which were published in the journal, “Nutrients”, supplies further evidence for the mental health benefits of maximizing vegetable and minimizing sodium consumption.

2. Behavioral importance of dietary carbohydrate as part of a Dietary Guidelines for Americans based diet. Vulnerability to mental stress is linked to chronic disease risk and exacerbation of chronic disease status. In an eight-week randomized control trial that compared effects of a healthy Dietary Guidelines for Americans (DGA)-based diet and relatively more unhealthy diet (based on the typical American diet), ARS researchers in Davis, California, learned that increasing dietary carbohydrate as part of the DGA-based diet reduced concentrations of a key stress response hormone, cortisol, and dampened psychological stress-induced cortisol reactions. These novel findings provide new evidence suggesting that, in the context of a healthy whole food diet, carbohydrate consumption may provide some protection from stress-related disease risk in some people. Furthermore, this apparent stress and cortisol dampening effect could reduce stress-related eating and improve the ability to sustain a healthier diet based on the DGA.

3. Omega-3 supplement doses to reduce cardiovascular risk. The omega-3 index is a simple status marker of long-chain omega-3 fatty acid consumption that is negatively associated with cardiovascular risk. From a clinical research study of long chain omega-3 fatty acid supplementation, predictive algorithms were developed by ARS researchers in Davis, California, using factors that influence how omega-3 supplementation influences the omega-3 fatty index. It was determined that body mass index, supplement dose, and the baseline omega-3 index explained over 60% of the variability in individual responses, and that consuming omega-3 fatty acids as triglycerides was approximately one and a half times more efficient than consuming phospholipids. The models generated can be used by clinicians to recommend efficacious omega-3 fatty acid doses and by researchers to estimate appropriate doses to reach beneficial omega-3 index levels in their study population. These findings, which were reported in the journal, “Nutrients”, provide important tools to both understand and improve cardiovascular health through the use of dietary supplements.

4. ALA-enriched butter reduces insulin resistance and supports omega-3 rich food consumption. Consuming butter enriched with the plant derived omega-3 fatty acid, alpha-linolenic acid (ALA), can reduce obesity and insulin resistance, which may decrease the risk for diabetes and cardiovascular diseases in overweight individuals. ALA cannot be synthesized in the human body and must be obtained from the diet to produce long chain omega-3 fatty acids which have diverse beneficial roles in human health. In collaboration with researchers at the University of Nebraska, ARS researchers in Davis, California, conducted experiments to determine if consuming ALA-enriched butter would reduce diet-induced obesity and its associated inflammation in a rodent model. ALA feeding reduced liver triglyceride accumulation and inflammation in body fat tissue and reduced insulin resistance. These findings suggest that consuming ALA-enriched butter conferred metabolic benefits against obesity-induced inflammation. These results also further support the cardioprotective benefits of consuming plant-based omega-3 fatty acids, and will be valuable to biomedical researchers, health care providers, and food manufacturers.

5. Blood lipid lowering effects of consuming chardonnay grape pomace powder. Grape pomace, a byproduct of winemaking, is a valuable, nutrient-rich agricultural resource that is underutilized, used mainly as landfill, animal feed, or recycled as compost. A study of healthy adults by ARS researchers in Davis, California, showed that consuming chardonnay grape pomace mixed with soluble extracts of the grape altered the blood lipid response after participants were challenged with a mixed breakfast meal. The pomace blend with higher fiber content produced lower triglycerides in the circulation following the meal, compared to the blend with higher extract content or the control. The significance of this finding is that circulating triglyceride concentrations are recognized as an important risk factor for cardiovascular disease. The higher fiber blend has greater nutritional complexity as it also contains essential micronutrient minerals, flavonoids, essential fatty acids, sterols, and stanols, making it a potentially important food ingredient to be used in heart-healthy food products.

6. Efficient analysis of multiple nutrients in human milk. Human milk composition, including its nutrient content, is now recognized to be affected by maternal diet and/or nutritional status. To provide Reference Values for the usual range of nutrients in milk from well-nourished women, ARS investigators in Davis, California, have developed and validated analytical methods that measure multiple nutrients simultaneously in small volumes of sample. Novel analytical methods have been developed, which now allow the accurate measurement of milk vitamins and minerals using lowest sample volumes to date, and providing accurate data in less time, including for concentrations of the many micronutrients and metabolites in milk previously not analyzable or measured with inaccurate methods. The new methods include ultra performance liquid chromatography (UPLC)-mass spectrometry, high pressure liquid chromatography coupled to fluorescence or ultraviolet detection, immunoassays, inductively coupled plasma mass spectrometry, and targeted metabolomics. These analytical methods are being used to measure milk composition in a four-country research project supervised by the ARS researchers in Davis, California.

7. Methods and protocols to validate the genetic regulation of the microbiome. The gut microbiome consists of a diverse number of microbial organisms, which can have detrimental and beneficial effects on health-related functions in the body. ARS investigators in Davis, California, developed and validated fecal microbiota transplantation (FMT), which is a procedure for implanting intestinal microbiota from a donor animal to the gastrointestinal tract of another animal. The microbiota from two types of mice (C57BL/6J and WSB/EiJ) differing in body fat and glucose tolerance were collected and transplanted into C57BL/6J mice previously treated with antibiotics to remove the microbiota. Unexpectedly, mice receiving WSB/EiJ microbiota had increased body fat, but improved glucose sensitivity. Large scale profiling and detailed analysis of the metabolites and microbiota in these mice indicated broad metabolic changes during and after FMT, which may explain the study results and provide novel pathways of disease susceptibility.

U.S. DEPARTMENT OF AGRICULTURE

Obesity and Metabolism Research: Davis, CA