1a. Objectives (from AD-416)
1. Assess the relationship between plasma biomarkers of nutrient intake and heart health. 2. Characterize the relationship between plasma markers of cholesterol homeostasis, dietary intake and intestinal cholesterol absorption protein genotypes, and heart health using samples from the Framingham Offspring Study. 3. Assess the value of glycemic index (GI) as a component of dietary guidance to promote heart health and decrease the risk of chronic diseases associated with aging. 4. Assess the relationship between the red blood cell fatty acid profiles and indicators of heart health in subjects consuming diets enriched in trans fatty acids derived from ruminant fat and partially-hydrogenated vegetable oils. 5. Assess the efficacy of a comprehensive family centered lifestyle modification program – Family Weight Study (FamWtStudy) – using biomarkers of nutrient intake and cardiovascular risk factors in family member pairs (female parent/guardian and child) after initiation of a comprehensive year long program.
1b. Approach (from AD-416)
In the next 5 years the Cardiovascular Nutrition Laboratory will assess the relationship between cardiovascular health and biomarkers of nutrient intake relative to food frequency data using Women’s Health Initiative samples by measuring nutrient intake biomarkers (plasma phospholipid trans fatty acids, eicosapentaenoic acid and docosahexaenoic acid, and phylloquinone and dihydrophylloquinone) and relating these data to cardiovascular health; identifying dietary patterns from food frequency questionnaire data and relating to cardiovascular health; and developing an algorithm using these data that best predicates cardiovascular health; assess the relationship between biomarkers of cholesterol homeostasis and modifiers thereof using plasma samples from the Framingham Offspring Study by measuring plasma cholesterol absorption (sitosterol, campesterol, cholestanol) and biosynthesis (desmosterol, lathosterol, squalene) marker concentrations and relating these data to cardiovascular health as modified by dietary intake and selected genotypes; and evaluate glycemic index (GI) as a component of dietary guidance to decrease chronic diseases risk by determining the reproducibility and variability of GI value determinations in volunteers differing in BMI, age, and gender; assessing the effect of macronutrient amounts and combinations, and fiber on GI and glycemic load (GL) value determinations; and determining the effect of macronutrient composition (carbohydrate, fat, and protein) of a prior meal (“second meal” effect) on GI and GL value determinations.
3. Progress Report
We completed analysis of food frequency data for Women’s Health Initiative (WHI) control and coronary heart disease (CHD) cases and modeled the data to assess dietary patterns. The results indicate that 6 principal components (diet factors) explained >75% of the variation and 3 Diet Clusters (DC); DC #1 is high in carbohydrate, vegetable protein, fiber, dietary vitamin K, folate and carotenoids, and supplemental calcium and vitamin D; DC #2 is high in total and animal protein, fish derived n-3 fatty acids, and dietary vitamin D and calcium and DC #3 is high in energy, fat, linoleic, arachidonic, alpha-linolenic and trans fatty acids. DC #1 was associated with a lower CHD risk than DC #2 after adjusting for BMI, LDL and energy. These differences did not remain significant after adjustments for energy, diabetes and dyslipidemia medication. In the same subjects we completed measurement of nutrient intake plasma biomarkers. These data are currently being modeled. We completed analysis for the measurement of plasma phytosterol, cholestanol and cholesterol precursor concentrations for the Framingham Offspring study. First we focused on a subgroup with an established cardiovascular event (CVD) who were not taking lipid lowering medication, cases, and matched controls. Cholesterol absorption markers were higher, whereas cholesterol synthesis markers were lower in CVD cases compared to controls. After controlling for standard risk factors, plasma indicators of cholesterol absorption were associated with increased CVD risk whereas indicators of cholesterol synthesis were associated with decreased CVD risk. We completed the replicate glycemic index (GI) measures, using white bread and glucose in 60 volunteers recruited to differ by sex, age and BMI. The mean (± SD) GI value for white bread was 63 ± 16. Intra-individual coefficient of variation (CV) ranged from 2% to 77%. The inter-individual CV was 25%. These data indicate that variability in GI value determinations is explained, in part, by differences in age, but not sex or BMI. The next phase of the work has been subdivided into 4 substudies focused on total carbohydrate, protein, fat and fiber. We have completed the GI challenges for studies 1 and 2, and have completed all but 6 subjects for substudy 3, and 9 subjects for substudy 4. We will commence analyzing the data after the substudies are completed. National Program Component 2B Scientific Basis for Dietary Guidance for Healthy Americans, Improve the Scientific Basis for Updating National Dietary Standards and Guidance 3B Prevention of Obesity and Related Diseases, Develop and Evaluate Strategies to Prevent Obesity and Related Diseases
1. F1B Golden-Syrian Hamster assessed as a model for diet-induced atherosclerosis.(2A) Golden-Syrian hamsters have been used as an animal model to assess diet-induced atherosclerosis since the early 1980s, but little data are available on the extent to which diet induced changes alters lesion development. ARS-funded researchers at JMUSDA-HNRCA at Tufts University, Boston, MA, evaluated impact of two potential determinants of lesions development: background diet composition (semi-purified, non-purified) and dietary fat type (coconut oil, safflower oil) on plasma lipoproteins profiles and aortic cholesterol accumulation. The researchers found that hamsters fed non-purified diets had higher plasma non-HDL cholesterol and TG concentrations compared to hamsters fed the semi-purified diets. Dietary fat type had no significant effect on plasma lipoprotein concentrations when hamsters were fed the semi-purified diets, however, coconut oil feeding resulted in higher non-HDL cholesterol and triglyceride concentrations than safflower oil when hamsters were fed the non-purified diets. Regardless of lipoprotein profile, there was no evidence of diet induced aortic cholesterol accumulation in any of the hamster groups. These data suggest the F1B Golden Syrian hamster may not be a useful model to determine the mechanisms underlying diet-induced atherosclerosis.
2. Long-Term Fatty Acids Stability in Human Serum.(2B) Fatty acid profiles of biological specimens from epidemiological/clinical studies can serve as biomarkers to assess potential relationships between diet and chronic disease risk. Limited data are available regarding fatty acid stability in archived specimens following long-term storage, a variable that could affect result validity. Using gas chromatography (GC) methodology ARS-funded researchers at JMUSDA-HNRCA at Tufts University, Boston, MA, determined the effect of prolonged storage (8-10 years) at minus 80 degrees C on the fatty acid profiles of serum cholesteryl ester (CE), triglyceride (TG), and phospholipid (PL) fractions. The researchers found little change in fatty acid profiles over time. When differences were identified, they were quantitatively small and likely attributable to technical improvements in GC methodology rather than sample degradation. Therefore, storage at minus 80 degrees C up to 10 years does not significantly influence serum CE, TG, or PL fatty acid profiles, thus, the use of archived samples can provide valuable information on diet and chronic disease risk.