Social drift of cardiovascular disease risk factors in Africans from the North West Province of South Africa: the PURE study.

OBJECTIVE: This study examined whether the association between socio-economic status (SES) and cardiovascular disease (CVD) risk factors in black South Africans from the North West Province had shifted from the more affluent groups with higher SES to the less affluent, lower SES groups over a period of nine years. METHOD: Cross-sectional baseline data of 2 010 urban and rural subjects (35 years and older) participating in the Prospective Urban and Rural (PURE) study and collected in 2005 were analysed to examine the relationship of level of education, employment and urban or rural residence with dietary intakes and other CVD risk factors. These relationships were compared to those found nine years earlier in the Transition and Health during the Urbanisation of South Africans (THUSA) study conducted in the same area. RESULTS: The results showed that urban women had higher body mass index (BMI), serum triglyceride and fasting glucose levels compared to rural women and that both urban men and women had higher blood pressures and followed a more Westernised diet. However, rural men and women had higher plasma fibrinogen levels. The more highly educated subjects (which included both urban and rural subjects) were younger than those with no or only primary school education. Few of the risk factors differed significantly between education groups, except that more highly educated men and women had lower BMIs, and women had lower blood pressure and triglyceride levels. These women also followed a more prudent diet than those with only primary school education. Employed men and women had higher BMIs, higher energy intakes but lower plasma fibrinogen levels, and employed women had lower triglyceride levels. No significant differences in total serum cholesterol values were observed. CONCLUSION: These results suggest a drift of CVD risk factors from groups with higher SES to groups with a lower SES from 1996 to 2005, indicating that interventions to prevent CVD should also be targeted at Africans living in rural areas, those with low educational levels, and the unemployed.

The relationship between indices of iron status and selected anthropometric cardiovascular disease risk markers in an African population: the THUSA study.

There is evidence that certain indices of iron status are associated with anthropometric measures, which are used independently as markers of cardiovascular disease (CVD) risk. This study examined whether this association exists in an African population. The study was a cross-sectional comparative study that examined a total of 1 854 African participants. Ferritin was positively associated with body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), percentage body fat and subscapular skinfold thickness. Serum ferritin concentration was higher in the high-WHR category than the normal-WHR category for both genders. Additionally, WC and WHR increased with increasing ferritin concentrations in both genders. Serum iron was lower in the obese than the normal-weight and pre-obese women only. In this population-based study, increased serum ferritin concentrations associated positively with increased WHR and WC, indicating that individuals or populations at risk of iron overload as defined by high serum ferritin concentrations may be at a greater risk of developing CVD.

Poverty, malnutrition, underdevelopment and cardiovascular disease: a South African perspective.

This article explores possible mechanisms to explain the known relationships between poverty, undernutrition, underdevelopment and cardiovascular disease (CVD) in developing countries. Poverty is a multidimensional concept. It is both a cause and consequence of undernutrition. The article shows how malnutrition during pregnancy could lead to low birth-weight babies, who are not only at increased risk of mental and physical underdevelopment, but also 'programmed' to be at increased risk of CVD and other non-communicable diseases in adult life. The underdevelopment leads to decreased 'human capital and competence' with an inability to create food security and an enabling environment for self and family to escape poverty and undernutrition in the next generation. It is accepted that a lack of education and knowledge in the poor for primary prevention of CVD through healthy eating patterns and lifestyles, as well as limited access to healthcare services for secondary prevention and treatment contribute to CVD. This article postulates that the link between poverty and CVD in South Africa can be explained by the high prevalence of undernutrition in one- to nine year- old children (9% underweight, 23% stunted and 3% wasted), the high prevalence of overweight and obesity in adults (54.5% in white men and 58.5% in African women) as well as the negative trends in nutrient intakes when Africans (the population group with the largest numbers of poor people) urbanise, acculturate and adopt westernised eating patterns that will increase CVD risk. In conclusion, we plead for a holistic, integrated but transdisciplinary and multisectorial approach to break the vicious circle of poverty and undernutrition for the longterm prevention of CVD.

Cardiovascular disease risk factors and socio-economic position of Africans in transition: the THUSA study.

In many developing countries with advanced stages of the nutrition transition, the burden of coronary artery disease (CAD) has shifted from the rich to the poor. In South Africa, it is mainly the African population that is experiencing rapid urbanisation and the nutrition transition. It is not clear where the burden of CAD lies in this population group. We tried to answer this question by comparing CAD risk factors within African groups of different socio-economic positions (characterised by total household income and education level) that participated in the THUSA study from 1996 to 1998. The THUSA study was a cross-sectional population- based epidemiological study that examined the influence of urbanisation and related changes in lifestyle and eating patterns on health and disease risk. A total of 1 854 apparently healthy African volunteers were recruited from 37 randomly chosen sites in rural and urban areas of the North-West Province. The results indicated that although the group with the highest socio-economic position had significantly lower serum glucose levels, systolic blood pressures, higher micronutrient intakes and fewer smokers, their sustained increases in total and saturated fat intakes and higher serum total and LDL cholesterol levels, as well as increased body mass indices in men suggested that at that point in time and possibly in the foreseeable future, the burden of CAD will be carried by those Africans with higher socio-economic positions.

Predictors of South African male testosterone levels: the THUSA study.

The process of urbanization occurring in many developing countries may have consequences for reproductive endocrine function. Here, we test predictions concerning variation in South African male testosterone levels among subgroups across an urbanization gradient representing differences in both geography and socioeconomic status. Subjects included 364 males aged between 20 and 82 comprising a cross-sectional study conducted between 1996 and 1998. Testosterone levels were measured from serum samples obtained between 08:00 and 11:00. In ANCOVA analysis, male testosterone levels differed significantly along this rural-to-urban gradient, with members of the most urban group having higher testosterone levels than groups of farmers and inhabitants of informal housing areas adjacent to towns. Testosterone levels declined with age and were negatively related to body mass index (BMI). Testosterone levels did not differ according to HIV status. Further exploratory ANCOVA analyses revealed that physical activity levels, depression, affect, and hostility were not significantly associated with variation in testosterone levels. These data help document causes of variation in male testosterone levels in a context of urbanization and may have implications for clinical outcomes such as the development of a male hormonal contraceptive or prostate cancer.

Integrated nutrition science: from theory to practice in South Africa.

OBJECTIVE: To describe an integrated, holistic conceptual framework and research paradigm for a better understanding of the nutrition transition in middle- and low-income countries. MOTIVATION: Current inability effectively to prevent the increasing burden related to changes in food consumption patterns and other health behaviours of populations in transition motivates a new approach for nutrition research and practice. In this proposed approach, broader and integrated dimensions of science and practice may be applied for a better understanding of this complex phenomenon. RESULT: Examples from our own studies are given and quoted to illustrate how results from transdisciplinary studies were used to design an integrated, holistic programme to improve quality of life of people infected with HIV. CONCLUSION: Based on these experiences it is argued that the more holistic and integrated approach should and could lead to more effective and sustainable interventions to prevent the adverse health consequences of the nutrition transition. At the same time such an approach will contribute to efforts to conserve the environment and also human, living and natural resources.

The National Food Consumption Survey (NFCS): South Africa, 1999.

OBJECTIVE: The aim of the National Food Consumption Survey (NFCS) in South Africa was to determine the nutrient intakes and anthropometric status of children (1-9 years old), as well as factors that influence their dietary intake. DESIGN: This was a cross-sectional survey of a nationally representative sample of all children aged 1-9 years in South Africa. A nationally representative sample with provincial representation was selected using 1996 Census information. SUBJECTS: Of the 3120 children who were originally sampled data were obtained from 2894, a response rate of 93%. METHODS: The sociodemographic status of each household was assessed by a questionnaire. Dietary intake was assessed by means of a 24-hour recall and a food-frequency questionnaire from the caregivers of the children. Food purchasing practices were determined by means of a food procurement questionnaire. Hunger was assessed by a modified hunger scale questionnaire. Nutritional status was determined by means of anthropometric measurements: height, weight, head circumference and arm circumference. RESULTS: At the national level, stunting (height-for-age below minus two standard deviations (< -2SD) from the reference median) was by far the most common nutritional disorder, affecting nearly one in five children. The children least affected (17%) were those living in urban areas. Even with regard to the latter, however, children living in informal urban areas were more severely affected (20%) compared with those living in formal urban areas (16%). A similar pattern emerged for the prevalence of underweight (weight-for-age < -2SD), with one in 10 children being affected at the national level. Furthermore, one in 10 (13%) and one in four (26%) children aged 1-3 years had an energy intake less than half and less than two-thirds of their daily energy needs, respectively. For South African children as a whole, the intakes of energy, calcium, iron, zinc, selenium, vitamins A, D, C and E, riboflavin, niacin, vitamin B6 and folic acid were below two-thirds of the Recommended Dietary Allowances. At the national level, data from the 24-hour recalls indicated that the most commonly consumed food items were maize, sugar, tea, whole milk and brown bread. For South African children overall, one in two households (52%) experienced hunger, one in four (23%) were at risk of hunger and only one in four households (25%) appeared food-secure. CONCLUSION: The NFCS indicated that a large majority of households were food-insecure and that energy deficit and micronutrient deficiencies were common, resulting in a high prevalence of stunting. These results were used as motivation for the introduction of mandatory fortification in South Africa.

Empowered women, social networks and the contribution of qualitative research: broadening our understanding of underlying causes for food and nutrition insecurity.

OBJECTIVE: To investigate underlying causes for food and nutrition insecurity in black South African households and to gain understanding of the factors contributing to better nutrition security, with emphasis on household organisation, gender and intra-household dynamics and social networks. DESIGN, SETTING AND SUBJECTS: Within a larger cross-sectional survey that investigated the impact of urbanisation on the health of black South Africans, 166 people, mostly women, were interviewed on household food security. Methods used were structured face-to-face interviews, in-depth interviews, observation, interviews with key informants and a sociodemographic questionnaire. Information was collected from 1998 to 2000 in 15 rural and urban areas of the North West Province, South Africa. RESULTS: Three-quarters of households in this sample are chronically food-insecure. Families are disrupted, due to migrant work, poverty and increasing societal violence, and half of households are female-headed. Certain categories of female-headed households and households based on partnership relationships, despite more limited resources, achieve a better or an equal economic status and better nutrition security than those households led by men, with the latter often being considered an economic liability. The reliance on and fostering of social ties and networks appear to be of central significance. CONCLUSION: Gender and intra-household relations, as well as social networks and income from informal sector activities, are often not uncovered by conventional statistical methods. Qualitative research can reveal the unexpected and furthermore empowers people, as their voices are heard.

Determination of the glycaemic index of foods: interlaboratory study.

OBJECTIVE: Practical use of the glycaemic index (GI), as recommended by the FAO/WHO, requires an evaluation of the recommended method. Our purpose was to determine the magnitude and sources of variation of the GI values obtained by experienced investigators in different international centres. DESIGN: GI values of four centrally provided foods (instant potato, rice, spaghetti and barley) and locally obtained white bread were determined in 8-12 subjects in each of seven centres using the method recommended by FAO/WHO. Data analysis was performed centrally. SETTING: University departments of nutrition. SUBJECTS: Healthy subjects (28 male, 40 female) were studied. RESULTS: The GI values of the five foods did not vary significantly in different centres nor was there a significant centrexfood interaction. Within-subject variation from two centres using venous blood was twice that from five centres using capillary blood. The s.d. of centre mean GI values was reduced from 10.6 (range 6.8-12.8) to 9.0 (range 4.8-12.6) by excluding venous blood data. GI values were not significantly related to differences in method of glucose measurement or subject characteristics (age, sex, BMI, ethnicity or absolute glycaemic response). GI values for locally obtained bread were no more variable than those for centrally provided foods. CONCLUSIONS: The GI values of foods are more precisely determined using capillary than venous blood sampling, with mean between-laboratory s.d. of approximately 9.0. Finding ways to reduce within-subject variation of glycaemic responses may be the most effective strategy to improve the precision of measurement of GI values.

Impact of urbanisation on serum lipid profiles--the THUSA survey.

OBJECTIVE: To examine the impact of urbanisation on lipid profiles of black South Africans, stratified for HIV status. DESIGN: Cross-sectional population-based survey. SETTING: North West province of South Africa. SUBJECTS: A representative sample of 1,854 apparently healthy volunteers aged > or = 15 years, was recruited from 37 randomly selected sites throughout the province. Subjects were stratified into five urbanisation strata (S): S1 rural villages, S2 farms, S3 informal housing or 'squatter camps' S4 urban townships, and S5 surburban housing. OUTCOME MEASURES: Demographic, physical activity and dietary intake information was collected using validated and culture-sensitive questionnaires. Anthropometric measurements and lipid analyses were determined using standardised methodology. RESULTS: The results revealed significantly lower mean (95% confidence interval) total serum cholesterol (TC) levels in HIV-negative men in S1-S4 compared with S5 (S1 3.91 (3.77-4.05) v. S5 4.79 (4.54-5.04) mmol/l). In HIV-negative women, TC levels were significantly lower in S1-S3 than in S4 and S5 (S1 4.05 (3.94-4.17) v. S5 4.79 (4.59-5.00) mmol/l). The same trends were seen for serum low-density lipoprotein cholesterol (LDLC) and triglycerides and in HIV-positive subjects. Binary logistical analysis indicated that the main factor responsible for the increased TC levels seemed to be increased body mass index (BMI) due to decreased physical activity. CONCLUSIONS: Serum lipid levels increased with urbanisation although they remained within levels recommended for other populations. This may, however, become an important health problem in future if preventive strategies are not implemented. Culturally sensitive physical activity programmes to decrease BMI, targeted at professional men and women, and women in urban townships, seem to constitute the most appropriate intervention.

The emergence of cardiovascular disease during urbanisation of Africans.

OBJECTIVE: To review the available data on risk factors for cardiovascular disease (CVD), the influence of urbanisation of Africans on these risk factors, and to examine why stroke emerges as a higher risk than ischaemic heart disease (IHD) in the health transition of black South Africans. DESIGN: A review of published data on mortality from and risk factors of CVD in South Africans. SETTING: South Africa. SUBJECTS: South African population groups and communities. METHODS: The available data on the contribution of stroke and IHD to CVD mortality in South Africa are briefly reviewed, followed by a comparison of published data on the prevalence and/or levels of CVD risk factors in the different South African population groups. The impact of urbanisation of black South Africans on these risk factors is assessed by comparing rural and urban Africans who participated in the Transition and Health during Urbanisation of South Africans (THUSA) study. RESULTS AND CONCLUSIONS: The mortality rates from CVD confirmed that stroke is a major public health problem amongst black South Africans, possibly because of an increase in hypertension, obesity, smoking habit and hyperfibrinogenaemia during various stages of urbanisation. The available data further suggest that black South Africans may be protected against IHD because of favourable serum lipid profiles (low cholesterol and high ratios of high-density lipoprotein cholesterol) and low homocysteine values. However, increases in total fat and animal protein intake of affluent black South Africans, who can afford Western diets, are associated with increases in body mass indices of men and women and in total serum cholesterol. These exposures may increase IHD risk in the future.