Body composition and the apoB/apoA-I ratio in migrant Asian Indians and white Caucasians in Canada

Migrant and native South Asians appear to be at increased risk of Type II diabetes mellitus and coronary disease. The aim of the present study was to determine the relationship between the most accurate summary index of the lipoprotein-related risk of vascular disease, the apoB (apolipoprotein B-100)/apoA-I (apolipoprotein A-I) ratio, and body composition in established migrant South Asians and white Caucasians living in Canada. Men and women living in Montreal, Canada between the ages of 20–60 years were recruited for participation in the study. Subjects were excluded if they had a history of cardiovascular disease or were taking lipid-lowering medication. Individuals identified themselves as Asian Indian or Caucasian. Anthropometric measurements were collected, including weight, height, waist circumference, hip circumference and body fat percentage. Plasma samples were analysed for total cholesterol, HDL-C (high-density lipoprotein-cholesterol), apoA-I and apoB. Indian subjects had a substantially higher WHR (waist-to-hip ratio) than Caucasian subjects [men, 0.93±0.01 compared with 0.86±0.01 respectively (P<0.001); women, 0.88±0.01 compared with 0.77±0.01 respectively (P<0.0001)]. WHR correlated strongly with body fat percentage in Caucasians (men, r=0.63, P=0.0002; women, r=0.74, P<0.0001). By contrast, there was no correlation in Indians (men, r=0.22, P value not significant; women, r=0.23, P value not significant). In addition, Indian men and women had a higher apoB/A-I ratio than Caucasians [men, 0.85±0.04 compared with 0.66±0.04 respectively (P=0.001); women, 0.73±0.04 compared with 0.56±0.03 respectively (P=0.0003)]. Of interest, there were also significant correlations between the apoB/apoA-I ratio and WHR in all of the groups, except the Indian women, which were stronger than the correlation of the apoB/apoA-I ratio with BMI. On the other hand, there was no significant relationship between the apoB/apoA-I ratio and the body fat percentage in any of the groups. In conclusion, the present study confirms that, as body fat percentage increases, the distribution of body fat differs between migrant Indians and Caucasians living in Canada. It also relates differences in body fat distribution to differences in the apoB/apoA-I ratio, providing at least part of the answer as to why South Asians may be at increased risk of vascular disease.