Small organs with a high metabolic rate explain lower resting energy expenditure in African American than in white adults


Gallagher, Dympna, Albu, Jeanine, He, Qing, Heshka, Stanley, Boxt, Lawrence, Krasnow, Norman and Elia, Marionos (2006) Small organs with a high metabolic rate explain lower resting energy expenditure in African American than in white adults. American Journal of Clinical Nutrition, 83, (5), 1062-1067.

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Description/Abstract

Background: African Americans have a lower resting energy expenditure (REE) relative to fat-free mass (FFM) than do whites. Whether the composition of FFM at the organ-tissue level differs between African Americans and whites and, if so, whether that difference could account for differences by race in REE are unknown.

Objective: The objectives were to quantify FFM in vivo in women and men at the organ-tissue level and to ascertain whether the mass of specific high-metabolic-rate organs and tissues differs between African Americans and whites and, if so, whether that difference can account for differences in REE.

Design: The study was a cross-sectional evaluation of 64 women (n = 34 African Americans, 30 whites) and 35 men (n = 8 African Americans, 27 whites). Magnetic resonance imaging measures of liver, kidney, heart, spleen, brain, skeletal muscle, and adipose tissue and dual-energy X-ray absorptiometry measures of fat and FFM were acquired. REE was measured by using indirect calorimetry.

Results: The mass of selected high-metabolic-rate organs (sum of liver, heart, spleen, kidneys, and brain) after adjustment for fat, FFM, sex, and age was significantly (P < 0.001) smaller in African Americans than in whites (3.1 and 3.4 kg, respectively; ± SEE difference: 0.30 ± 0.06 kg). In a multiple regression analysis with fat, FFM, sex, age, and race as predictors of REE, the addition of the total mass rendered race nonsignificant.

Conclusions: Racial differences in REE were reduced by >50% and were no longer significant when the mass of specific high-metabolic-rate organs was considered. Differences in FFM composition may be responsible for the reported REE differences.

Item Type: Article
Additional Information: Original research communication
ISSNs: 0002-9165 (print)
Related URLs:
Keywords: race, ethnicity, african americans, whites, metabolism, organs, tissues, fat-free mass, resting energy expenditure, magnetic resonance imaging
Subjects: H Social Sciences > HT Communities. Classes. Races
Q Science > QP Physiology
Divisions: University Structure - Pre August 2011 > School of Medicine > Developmental Origins of Health and Disease
ePrint ID: 44173
Date Deposited: 19 Feb 2007
Last Modified: 27 Mar 2014 18:28
URI: http://eprints.soton.ac.uk/id/eprint/44173

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