Location: Healthy Body Weight Research2013 Annual Report
1a. Objectives (from AD-416):
Objective 1: Develop and validate assessments of behavioral factors that influence energy intake by a) development and validation of a satiety index of foods that reflects interactions of food with physical activity, body mass index, gender, and age; and b) determination of the effect of exercise on energy intake and eating rate. Objective 2: Develop methods for assessing patterns of energy expenditure that include a) validation of breath markers as indicators of energy substrate utilization and; b) characterization of seasonal patterns of energy expenditure and balance in free-living individuals using novel applications of existing technologies (e.g., GPS, accelerometry, heart rate monitoring, doubly labeled water).
1b. Approach (from AD-416):
To complete the objectives of this proposal, we will conduct a series of studies with human volunteers. For Objective 1, we will model the satiating effects of selected individual food items and mixed meals. Our model will include the comparisons of hormonal and metabolic responses to food consumption to subjective satiety responses and subsequent energy intake, which we will evaluate in a repeated measures design human trial. In Objective 2a, we will conduct controlled feeding studies to determine the effects of caloric restriction and exercise on breath markers of substrate utilization. In Objective 2b, we will identify seasonal changes in body fat, as well as where, how much, and when physical activity and dietary intake vary seasonally.
3. Progress Report:
Obj 1a. A pilot study of first 10 participants is complete and data analysis is underway; recruitment of additional participants and additional studies for remainder of project are ongoing. Obj2a. Data analysis for Expt 2 completed; invention disclosure submitted; abstract and manuscript in preparation. Internal protocol approved for Expt 1; diet designed and analyzed; IRB application approved. Obj 2b. Data collection for year 1 cohort complete; recruitment for year 2 cohort is complete and data collection underway. Sample and data analysis is in progress and abstracts are in preparation. Obj 3a. Project developed and reviewed by Center scientists, will be submitted for IRB review. Obj 3b. Completed follow-up data collection of original cohort of sibling subjects. Developed and received IRB approval for a second cohort of siblings. Data analysis has begun. Began recruitment and study of second cohort. Ancillary project: examining community-based lifestyle intervention for weight loss and improvements in body composition, fitness, and chronic disease risk biomarkers. All data analyzed; manuscript in review. Ancillary project: validating use of resonance Raman spectroscopy for measuring skin carotenoids as non-invasive tool to assess fruit & vegetable intake (blood carotenoids are current standard biomarker); in collaboration with investigators at Yale and University of Utah. Data collection complete; analysis nearly complete. Two additional abstracts published (oral and poster). Invited review published; manuscripts in preparation. Ancillary project: ARS multi-site project “HEALTH” describing barriers and facilitators to following dietary guidelines reported by 5th graders and caregivers. Data collection complete; analysis ongoing. Manuscript in review; two abstracts published (oral and poster), one manuscript published; others in preparation. Ancillary project: describing barriers and facilitators to following the dietary guidelines reported by 5th grade American Indian children and parents; in collaboration with investigators at Cankdeska Cikina Community College. Data collection complete. Manuscript in review. Ancillary project: investigating an after-school intervention to increase nutrition knowledge and cooking skills of low-income adolescents and test the use of a mobile phone application for collecting dietary intake data. Data collection complete; analysis nearly complete. One abstract published (oral abstract). Manuscripts in preparation.
1. Comparison of breath carbon stable isotope ratio before and after exercise can confirm negative energy balance. Demonstrated that comparison of breath carbon stable isotope ratio can be used before and after exercise to determine if a person is in negative energy balance.
2. Skin carotenoids predict plasma carotenoids. Blood levels of carotenoids are considered the best biomarker of consumption of fruit and vegetable (FV) intake by humans. However, blood collection is invasive and not practical for large-scale studies. Skin carotenoid detection based on Raman resonance spectroscopy is a promising new method of non-invasively measuring effectiveness of FV-promoting interventions. ARS scientists at Grand Forks, ND demonstrated that skin carotenoids predict plasma carotenoid levels during a 28-week feeding study with varying levels of vegetables and fruits, confirming that Raman resonance spectroscopy can be reliably used as a non-invasive biomarker of vegetable and fruit intake.
3. Carotenoid-rich diet improves plasma inflammatory markers. Fruits and vegetables contain high levels of carotenoids, compounds that have anti-inflammatory properties. ARS scientists at Grand Forks, ND demonstrated that consumption of a carotenoid-rich diet improves plasma inflammatory markers. Levels of pro-inflammatory cytokines were not changed by depletion of dietary carotenoids, but were decreased upon consumption of a high-carotenoid diet.
4. Subjective assessment of satiety (hunger, fullness) is correlated to plasma ghrelin levels. The subjective assessment of hunger and fullness by responses on a visual analog scale (VAS) were compared to the measured biochemical marker of ghrelin in the blood. The responses of the subjective and biochemical markers to a standard test meal of full fat, sweetened Greek yogurt were highly correlated in each person across three repeated testing periods. These initial results confirm that ARS scientists in Grand Forks, ND have developed a testing method for the satiety value of foods that will allow continued work in this area.
5. Fish for cardiovascular disease risk reduction. ARS scientists in Grand Forks, ND were invited to write a review for a special issue of the journal Nutrients because of their investigations with farmed Atlantic salmon. A paper was written and subsequently published that discusses the role of fish intake on cardiovascular disease reduction in humans. The current intake of fish in the United States and as the fishing industry were discussed. The paper was published in March 2013.
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