Adisposity and CVD risk factors: A comparison between ethnicities

Background: The prevalence of overweight, obesity and obesity-related disease, mainly cardiovascular disease (CVD), is increasing in both developed and developing countries. Ethnic differences have been reported in the prevalence of overweight, obesity and CVD. However, measures used to define overweight and obesity, and identify increased risk of CVD were developed and validated in predominately Caucasian populations in developed countries. Consequently, these measures may not accurately define disease risk in all population groups. Therefore the specific aims of this programme of study were: 1. To establish the relationship between adiposity and cardiovascular risk factors in different ethnic groups. 2. To identify field measures of adiposity, relating to cardiovascular risk in different ethnic groups. 3. To compare the relationship of adiposity and cardiovascular risk factors in a single ethnic group, that of a rural and an urban population in Zimbabwe. 4. To identify risk factors for CVD related to adiposity in a population of African origin. Study design: Three empirical studies were undertaken. In study one, 312 adult subjects from three ethnic groups (Afro-Caribbean (n=106), Caucasian (n=165) and South Asian (n=41)) were recruited from a University. Twenty-six (26) of each group were individually matched for age (±3 years) gender and BMI (±2 kg/m2) to allow for comparability. Measures of body composition included height, weight, waist and hip circumferences, skinfold thickness measures, body density and percentagebody fat. In study two, 81 subjects from two ethnic groups (Afro-Caribbean (n=39) and Caucasian (n=42)) were recruited and tested. They were matched for age, gender and BMI using the same criteria as study one. In addition to the body composition measures taken in study one, random non-fasting blood glucose, total cholesterol, triglycerides and blood pressure were taken. In study three, 55 men and 108 women from rural Zimbabwe, 8 men and 17 women from an urban low-density suburb in Harare Zimbabwe, and 28 male and 16 female students from the University of Zimbabwe were recruited and tested. In addition to all measures of body composition in studies one and metabolic analysis in study two, participants’ dietary intake was assessed by food frequency questionnaire and 24hour recall and physical activity was assessed by a physical activity questionnaire. Main findings: • The relationship between BMI and %BF was not the same in all ethnic groups. (aim 1) • There were ethnic differences in the cardiovascular risk predictors between Afro-Caribbean and Caucasian men and women. (aim 1) • It is not recommended that BIA is used as a substitute for TBW estimation in multi-compartment models. (aim 2) • In three groups of Zimbabweans from urban, rural and university locations, a pattern emerged. Amongst women, urban women were at greatest risk, reporting highest values for all variables, followed by rural then university women. Amongst men, urban men were at highest risk, however there were few differences between rural and university men. (aim 3). • Finally, increased WC and dyslipidemia are associated with increasing BMI in populations of African origin. (aim 4) Conclusions: The relationships between overweight, obesity and risk of obesity-related disease differ between different ethnic groups. Moreover, in the groups from Zimbabwe, differences in obesity-related risk were associated with being female and living in urban areas. Therefore, application of universal measures for defining obesity and related diseases may not be applicable to all ethnic groups