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Objective. To assess the relationship between dietary factors and cardiovascular (CVD) risk factors in middle-aged men and women, in urban, rural and pastoral settings in Tanzania.Design. Cross-sectional epidemiological study designed according to the protocol of the World Health Organisation (WHO) Cardiovascular Diseases and Alimentary Comparison (CARDIAC) study.Setting. Three centres in Tanzania, namely Dar es Salaam (urban), Handeni (rural) and Monduli (pastoral population). Subjects. The subjects, aged 47 - 57 years, were recruited randomly from administrative lists available from each centre.Outcome measures. Blood pressure (BP) was measured using a centrally calibrated automatic BP machine (Khi machine). Dietary history of the participants was obtained using a standard questionnaire designed on the basis of a seven-day recall system. Height, weight, serum total cholesterol (TC) and high-density lipoprotein cholesterol (HDLC), haemoglobin A1c , sodium, potassium and magnesium were measured.Results. The prevalence of hypertension (BP ≥ 140/90 mmHg or antihypertensive drug use), obesity (body mass index (BMI)≥ 30 kg/m2) and hypercholesterolaemia (TC > 5.2 mmol/l) were lowest in the rural area. Consumption of green vegetables, milk, coconut milk, meat, and fish varied significantly between the three areas. Important determinants for BP among men were BMI (p < 0.001), and salt intake (p < 0.05). Among women, TC (p < 0.05), age (p < 0.05), BMI (p < 0.001) and coconut milk consumption (p < 0.001)were important BP determinants. Salt intake was positively associated with systolic BP (SBP) and diastolic BP (DBP) in men but not among women (both SBP and DBP p < 0.05 respectively). Dietary determinants of serum TC were meat, fish and green vegetable consumption.Conclusion. Differences in dietary habits contributed significantly to the urban-rural-pastoral variations in CVD risk pattern in Tanzania.

Spontaneously hypertensive rat (stroke-prone) (SHRSP) has an interestingly low serum cholesterol level due to a reduced biosynthesis of cholesterol in the liver (Iritani, N., Fukuda, E., Nara, Y., and Yamori, Y. (1977) Atherosclerosis 28, 217-222). In this study, we examined the mechanism underlying the reduction of hepatic cholesterol biosynthesis in the rat. Our initial findings in SHRSP, as compared with normotensive Wistar Kyoto rat (WKY), showed that 1) the incorporation of [14C]acetate into cholesterol in the liver slices was markedly less, 2) 3-hydroxyl-3-methylglutaryl (HMG) CoA reductase activity was not reduced, and 3) the incorporation of [3H]mevalonic acid into both cholesterol and squalene was significantly less. The above initial findings suggested that the reduction in the hepatic cholesterol biosynthesis took place in one or more enzymatic processes starting with mevalonic acid and continuing to squalene. When the incorporation of [3H]mevalonic acid into phosphomevalonate derivatives was studied using an ion exchange column, only the radioactivity incorporated into isopentenyl-pyrophosphate (isopentenyl-PP) was less in SHRSP. Furthermore, the specific activity of diphosphomevalonate (mevalonate-PP) decarboxylase in the liver-soluble fractions was reduced 50% in SHRSP as compared with WKY. Kinetic studies using liver crude extracts indicated a lower Vmax value in SHRSP (SHRSP, 0.47; WKY, 2.05 nmol/min/mg), and an unchanged Km value (SHRSP, 18.2; WKY, 19.6 microM). The activity of mevalonate-PP decarboxylase was also found to be reduced in other tissues, including the brain, testis, small intestine, and cultured vascular smooth muscle cells. From the above observations, we concluded that the lower activity of mevalonate-PP decarboxylase was responsible for the reduced cholesterol biosynthesis in the liver of SHRSP.