Performing Department
Human Sciences
Non Technical Summary
This study will investigate two questions that may affect chromium (Cr) status in the elderly. One question relates to dietary Cr intakes of older adults. When the Recommended Dietary Intakes (DRIs) for Cr were established in 2001, there were too few data to set an estimated average requirement (EAR) for Cr. Recommendations for adults 51 years of age and above were estimated at 30 ?g Cr/day for men and 20 ?g/day for women; however, the rapid increase in Type II diabetes in the elderly raises the question of the adequacy of this dietary recommendation. Our study will provide data on Cr intakes of older Oklahomans as well as information about intakes of magnesium, zinc, copper, and selected antioxidants. Secondly, we will investigate effects on Cr absorption of taking either aspirin or over-the-counter antacid compounds. Animal studies suggest that aspirin or antiacids dosed with chromium significantly raise or lower chromium absorption respectively. We propose to test the effects of both aspirin and a common antacid on chromium absorption in humans. This study will be conducted in older Oklahoma women with and without metabolic syndrome. Metabolic syndrome is defined as central obesity with any two of the following four factors: elevated triglycerides, blood sugar, or blood pressure or decreased HDL-cholesterol. People with metabolic syndrome have a five times greater risk of developing type 2 diabetes as well as having other risk factors for heart disease. The project will: 1) Assess dietary intakes of macronutrients, magnesium, micronutrients with antioxidant function, and specifically dietary chromium. 2) Relate glucose, insulin resistance and selected plasma markers of inflammation and oxidative stress to dietary intakes of chromium, magnesium and antioxidant nutrients, and 3) evaluate the effects of two commonly used over-the-counter medications on chromium absorption in these older adults. Duplicate plate diet samples from forty-four women as well as computer analysis of 4 three-day dietary records for each participant will be analyzed. Half of these women will have metabolic syndrome. Glucose and lipid profiles will be analyzed using standard clinical laboratory methods. Insulin resistance will be estimated using HOMA modeling. Selected markers in blood of inflammation and antioxidant status also will be analyzed. Diet samples will be handled using procedures appropriate for trace mineral testing. Data will be analyzed using SAS software, v.9.1. Multiple regression models will be used to assess relations between baseline variables, dietary chromium intakes and urinary chromium. The Proc Mixed procedure will be used for repeated measures analysis of effects of medications on chromium absorption. Both the food records and the duplicate plate analyses will help characterize the nutritional adequacy of diets of older Oklahomans. These data will be useful for extension programming and for preparation of proposals to obtain further funding for work on trace element status and metabolic syndrome in vulnerable population groups in Oklahoma.
Animal Health Component
(N/A)
Research Effort Categories
Basic
20%
Applied
80%
Developmental
(N/A)
Goals / Objectives
This project will contribute to the overall objectives of the W2002 Multistate Project entitled, "Nutrient Bioavailability-Phytonutrients and Beyond". These objectives are: 1) Determine the bioavailability (absorption, distribution, metabolism, elimination) of nutrients and other food components and their environmental and genetic determinants 2) Evaluate the bioactivity of nutrients and other food components in order to elucidate their underlying protective mechanisms. Specifically, for chromium, we hypothesize that: 1) Baseline body fat, fasting glucose concentration, and insulin resistance will be significantly related to dietary chromium intakes and to markers of oxidative stress and inflammation in healthy older Oklahomans and in those with metabolic syndrome. 2) Consumption of commonly used medications will significantly affect chromium absorption (assessed by urinary chromium excretion). Specific Aims: 1) Assess dietary intakes of macronutrients, magnesium, micronutrients with antioxidant function, and specifically dietary chromium. Further analyses will include glucose control and insulin resistance [using the homeostatic model assessment (HOMA)] of healthy older Oklahomans and of those with metabolic syndrome. 2) Relate circulating concentrations of selected adipokines and markers of inflammation and oxidative stress to dietary intakes of chromium, magnesium and antioxidant nutrients. 3) Evaluate the effects of two commonly used over-the-counter medications on chromium absorption in these older adults
Project Methods
Forty-four women >50 y will be recruited for this study with half having metabolic syndrome [defined as central obesity (≥ 88 cm) plus any two of the following four factors: triglycerides ≥ 150 mg/dL; HDL cholesterol <50 mg/dL; elevated blood pressure, systolic ≥ 130 or diastolic ≥ 85 mm Hg or hypertension treatment; fasting plasma glucose ≥ 100 mg/dL or previously diagnosed type 2 diabetes]. Four duplicate plate diet samples and four three-day dietary records will be collected from each participant. Furthermore, we will analyze effects of aspirin, antacid or placebo on chromium (Cr) absorption (assessed by urinary Cr 2 hours after dosing) in the same participants. Medications will be administed in a randomized cross-over design and each participant will serve as their own control. The study will be conducted in the following stages: Stage 1 - Screening. Screening will involve consent, a health questionnaire, measurement of central obesity and blood pressure and a venous blood sample for measuring glucose and lipid profiles. Qualified participants will be instructed in collection of duplicate plate diet samples and three-day dietary records. Stage 2 - Baseline. Participants will bring a duplicate plate dietary collection and a three-day diet record to the study headquarters. Baseline measurements of central obesity and blood pressure will be taken. A DEXA scan will be done for assessment of whole body and regional fat distribution and a blood sample will be drawn for analyses of insulin, glucose, lipids, C-reactive protein, and inflammatory cytokines as well as markers of antioxidant status. A urine sample will be aliquoted for analyses of Cr and of F2- isoprostanes. Participants will take a 100 mcg supplement of Cr chloride with a placebo tablet. Two hours later second samples of blood sample and urine will be collected; both will be analyzed for Cr. Stage 3 - Randomly Assigned Medication Treatment 1 (15 days after baseline). All diet, blood and urine collections will be repeated. Women will take a 100 mcg Cr supplement with either aspirin or antacid. Stage 4 - Baseline for Crossover (15 days after treatment 1). All diet, blood and urine collections will be repeated. Women will take a 100 mcg Cr supplement with a placebo. Stage 5 - Randomly Assigned Medication Treatment 2 (15 days after Stage 4). All diet, blood and urine collections will be repeated. Women will take a 100 mcg Cr supplement with a medication in a crossover design. Glucose, lipids, and insulin will be analyzed using standard methods. Insulin resistance will be estimated using HOMA modeling. TNF-α, IL-1, IL-6, adiponectin, F2-isoprostanes and hsCRP will be analyzed using ELISA techniques. Diet records will be analyzed using the Food Processor. Duplicate plate diet samples will be processed using a Stomacher. Diet samples will then be ashed in a muffle furnace using procedures appropriate for trace mineral testing and mineral concentrations will be determined using ICP-MS. Data will be analyzed using SAS software, v.9.1. The Proc Mixed procedure will be used for repeated measures analysis of effects of medications on chromium absorption.