Dietary fat intake and blood lipid profiles of South African communities in transition in the North–West Province : the PURE study
Aim and objectives: This study set out to investigate the diet and blood lipid profiles of subjects in transition in the North West Province in South Africa. It looked specifically at how the diet differed between rural and urban areas, how the blood lipid profiles differed between rural and urban subjects, establishing an association between dietary fat, fatty acid and cholesterol intakes respectively and blood lipid profiles, as well as investigating the differences in blood lipid profiles at different ages, body mass index (BMI) and genders respectively in rural and urban areas. Design: The present study was a cross–sectional data analysis nested within the Prospective Urban and Rural Epidemiology (PURE) study that is currently undertaken in the North West Province of South Africa amongst other countries. Methods: Baseline data was obtained in 2005. A randomised paper selection was done of people between 35 - 70 years of age with no reported chronic diseases of lifestyle, TB or HIV of those enrolled into the PURE study if they had provided written consent. Eventually a paper selection was made of 2000 subjects, 500 people in each of the four communities (rural, urban–rural, urban, established urban). For the interpretation purposes of this study, data was stratified for rural (1000 subjects) and urban (1000 subjects) only, with no further sub–division into communities. Physical activity levels and habitual diets were obtained from these subjects. Demographic and dietary intake data in the PURE study was collected using validated, culture sensitive questionnaires. Anthropometric measures and lipid analysis were determined using standardised methodology. Descriptive statistics (means, standard deviations and proportions) were calculated. One–way analysis of variance (ANOVA) was used to determine differences between the different levels of urbanisation on blood lipid profiles and dietary intake. When a dietary intake variable proved to be significant for different levels of a factor (urbanisation, blood lipid profile), post–hoc tests were calculated to determine which levels for specific variables differed significantly. Bonferroni–type adjustments were made for the multiple comparisons. Spearman correlations were calculated to determine associations. Results: Mean fat intake was significantly higher in urban areas than in rural areas (67.16 ± 33.78 g vs. 32.56 ± 17.66 g, p<0.001); and the same was true for the individual fatty acid intakes. Fat and fatty acid intakes were still within recommendations even for urban areas, and low for rural areas. N–3 intake was very low in both rural and urban areas. Serum lipids did not differ significantly between rural and urban areas. Almost half of rural (43%) and urban (47%) subjects presented with elevated total cholesterol (5.0 mmol/L). In rural areas 52% and in urban areas 55% of subjects had elevated LDL–C (3.0 mmol/L). Amongst 23% of males in rural areas and 18% of males in urban areas HDL–C levels were decreased. Of the females living in rural areas 34.3% had decreased HDL–C levels and 39% of those who lived in urban areas presented with lowered HDL–C levels. In rural areas 16.3% of subjects and in urban areas 23% of subjects presented with high triglyceride levels. TC, LDL–C and triglyceride levels were higher in higher body mass index (BMI) classes, however, obese subjects did not differ significantly from overweight subjects in terms of blood lipids, suggesting that values stabilise after reaching overweight status. These blood lipids were also higher in higher age groups and higher in women than men, probably due to the high incidence of obesity in women. Conclusions: Associations between the diet and blood lipid profiles were weak, and diet is not likely to be the only factor responsible for high TC and LDL–C levels. Blood lipid profiles did not differ significantly between rural and urban areas due to the fact that the diet was prudent in terms of fat intake in both rural and urban areas. Higher prevalence of underweight was noted in males (32% in rural areas and 28% in urban areas), while overwieght was a bigger problem amongst women (48% in rural areas and 54% in urban areas). TC, LDL–C and TAG were higher with higher BMI’s, while HDL–C levels were lower. TC, LDL–C, and TAG were higher in higher age goups while HDL–C levels were lower. Female subjects presented with higher mean triglycerides than males, probably due to higher prevalence of overweight and obesity.
- ETD@PUK