ETHNIC/RACIAL DIFFERENCES IN VISCERAL AND LIVER FAT DISTRIBUTIONS IN THE MULTIETHNIC COHORT

Loic LE MARCHAND, University of Hawaii Cancer Center, United States
LIM U. 1 , MONROE K. 2 , ERNST T. 3 , SHEPHERD J. 4 , WILKENS L. 1 , LE MARCHAND L. 1

1 University of Hawaii Cancer Center
2 University of Southern California
3 University of Hawaii Medical School
4 University of California San Francisco

Since 1992-1995, the Multiethnic Cohort (MEC) Study has followed over 215,000 men and women of five ethnic/racial groups (Japanese Americans, Latinos, whites, African Americans and Native Hawaiians). The associations of BMI to cancer and diabetes vary markedly across ethnicities. Thus, we examined differences in body fat distribution in the cohort.
 
Healthy MEC participants aged 60-73 years were recruited among each sex/ethnic group to undergo a whole-body DXA and abdominal MRI and anthropometric measurements. Recruitment was stratified across six BMI level (18.5-40 kg/m2) within each sex/ethnic group to maximize comparability in total adiposity.  Data analyses were completed on 300 subjects and are being conducted on 1,000 subjects (~100 by sex/ethnic groups).
 
By study design, mean BMI (28kg/m2) was similar for men and women and across ethnicities (p=0.80). Total percent body fat was higher in women (40%) than in men (27%), and differed by ethnicity only in women (p=0.007). Mean visceral fat area at L3/L4 in men, adjusted for total body fat and age, was largest for Japanese Americans (247cm2), followed by whites (207cm2), Latinos (198cm2), Native Hawaiians (194cm2) and African Americans (158cm2) (p-heterogeneity=0.0002). In women, differences were even greater in the following decreasing order: Japanese Americans (183cm2), Native Hawaiians (149cm2), whites (134cm2), Latinas (120cm2) and African Americans (90cm2) (p-het.<0.0001). Multivariate adjusted percent liver fat showed a 3.3-fold difference across ethnicities in both men (7.9%-2.4%) and women (9.5%-2.9%; both p-het.<0.0001) in a similar ethnic/racial order as with visceral fat, except that Latinas showed a higher percent liver fat than white women. Weight gain in adulthood (since age 21) among men, but not women, was associated with greater visceral fat (p=0.0004) and liver fat (p<0.0001) even after accounting for total fat.
 
The substantial differences in body fat distribution observed among ethnic groups may in part explain their differing metabolic disease burdens.