Evaluation of the relationship of Dairy and Meat consumption (as CLA content) with resting metabolic rate

Abstract

The primary goal of this research was to extract the dietary milk and meat consumption from three day food records of a previous study entitled "Food Habits and Behaviors, Metabolic Rate and Body Composition in College Females ages 18-26" to estimate the ingested conjugated linoleic acid (CLA). (1) In addition to the three day food records, the original data included using The Nutrition Electronic Tool (NET) with 38 college females to include self-reported markers of food habits, nutrition attitudes and dieting behaviors. Body fat was estimated using the BodPod® two compartment model, and resting metabolic rate was estimated using the MedGem® indirect calorimeter. The three day food records had been previously evaluated using Food Processor SQL. This current study used the quantities of foods recorded on the three day food records to estimate CLA content of the diet. The main focus was to examine the data for predictive value of estimated CLA consumption (from lean meat and low fat milk) for resting metabolic rate. Previous evaluation of this data indicated that consumption of lean meats and low fat dairy products improved body fatness and resting metabolic rate. These findings begged the question if CLA found in these food substances was a potential bioactive predictor of increased RMR. Once meat and milk products were recorded from the three day food records, total CLA content was manually estimated for each record using published values (2). CLA exists in various isomers with the c9t11 and t10c12 isomers as the most commonly studied. Published values of CLA content in foods allowed for estimation of the two more popular isomers for separate evaluation in this study. Evaluation for influence of CLA and the primary isomers in the diet followed a manual stepwise regression for the dependent variable Resting Metabolic Rate. Independent variables of interest considered in the resting metabolic rate modeling process included: waist, age, markers of nutrition attitudes, dieting behaviors, total food habits marker, body image, projected energy balance, BMI and weight alongside the CLA and CLA isomer variables. Results indicated that the best models of regression did not include CLA or the c9t11 isomer in the models. The best model for resting metabolic rate included the variables waist, height, age, meat preference, and Food Habit Questionnaire total. This study remains consistent with the previous findings. The data does not support an influential role for the CLA as estimated from three-day dietary records, but it does support a strong role for dietary habits and attitudes. Surprisingly, the insignificant beta values obtained for CLA suggests an inverse relationship of what was originally hypothesized. This study was more specific to the CLA dietary components than the original study. Electronic estimation of dietary CLA was not possible using current Food Processor SQL so this estimation was carried out manually. For future studies to be more accurate, database software that contains CLA content would be highly desirable and would likely produce more accurate values to include all foods.