Nelia P. Steyn

Diet, nutrition and the prevention of type 2 diabetes

OBJECTIVES The overall objective of this study was to evaluate and provide evidence and recommendations on current published literature about diet and lifestyle in the prevention of type 2 diabetes. DESIGN Epidemiological and experimental studies, focusing on nutritional intervention in the prevention of type 2 diabetes are used to make disease-specific recommendations. Long-term cohort studies are given the most weight as to strength of evidence available. SETTING AND SUBJECTS Numerous clinical trials and cohort studies in low, middle and high income countries are evaluated regarding recommendations for dietary prevention of type 2 diabetes. These include, among others, the Finnish Diabetes Prevention Study, US Diabetes Prevention Program, Da Qing Study; Pima Indian Study; Iowa Womens Health Study; and the study of the US Male Physicians. RESULTS There is convincing evidence for a decreased risk of diabetes in adults who are physically active and maintain a normal body mass index (BMI) throughout adulthood, and in overweight adults with impaired glucose tolerance who lose weight voluntarily. An increased risk for developing type 2 diabetes is associated with overweight and obesity; abdominal obesity; physical inactivity; and maternal diabetes. It is probable that a high intake of saturated fats and intrauterine growth retardation also contribute to an increased risk, while non-starch polysaccharides are likely to be associated with a decreased risk. From existing evidence it is also possible that omega-3 fatty acids, low glycaemic index foods and exclusive breastfeeding may play a protective role, and that total fat intake and trans fatty acids may contribute to the risk. However, insufficient evidence is currently available to provide convincing proof. CONCLUSIONS Based on the strength of available evidence regarding diet and lifestyle in the prevention of type 2 diabetes, it is recommended that a normal weight status in the lower BMI range (BMI 21-23) and regular physical activity be maintained throughout adulthood; abdominal obesity be prevented; and saturated fat intake be less than 7% of the total energy intake.

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.

Prevalence of cardiovascular diseases and associated risk factors in a rural black population of South Africa

Background To determine the prevalence and associated risk factors of cardiovascular diseases in a rural adult black population from Limpopo Province in South Africa. Design A cross-sectional study. Methods A sample of 1608 women and 498 men aged 30 years and above participated in the study. Sociodemographic data, anthropometric measures (body mass index, waist/hip ratio), blood pressure and biochemical risk factors were measured. A global cardiovascular disease (CVD) risk profile was developed. Results There was a high prevalence of tobacco use for men (57%) and women (35.4%), with women (28.1%) predominantly using smokeless tobacco. Alcohol use was very common in men (57.2%). Women weighed a great deal more than men, and 51.7% were either overweight or obese. Diabetes was diagnosed in 8.8 and 8.5% of women and men, respectively. High-density lipoprotein-cholesterol was relatively high, whereas 42.3% of women and 28.5% of men had low-density lipoprotein-cholesterol levels of 3 mmol/l or more. Hypertension (blood pressure ≥ 140/90 mmHg) was found in 25.5% of women and 21.6% of men. According to the Framingham formulae, 18.9% of women and 32.1% of men had a 20% or higher chance of having a CVD event in the next 10 years. Conclusions There was a high prevalence of chronic disease risk factors in the rural, poor black community in Limpopo, South Africa. Consequently, the population had a higher than expected risk of developing a CVD event in the following 10 years when compared with similar studies in black Africans.

Food security in South Africa: a review of national surveys

OBJECTIVE To assess the status of food security--i.e., access to food, food availability and food utilization--in South Africa. METHODS A systematic search of national surveys that used the Community Childhood Hunger Identification Project (CCHIP) index to measure food security in South Africa over a period of 10 years (1999-2008) was conducted. Anthropometric data for children aged 1-9 years were used to assess food utilization, and household food inventory data were used to assess food availability. FINDINGS Only three national surveys had used the CCHIP index, namely, the 1999 and 2005 National Food Consumption Surveys (NFCS) and the 2008 South African Social Attitudes Survey. These surveys showed a relatively large decrease in food insecurity between 1999 and 2008. However, the consistent emerging trend indicated that in poorer households women were either feeding their children a poor diet or skipping meals so their children could eat. In terms of food access and availability, the 1999 NFCS showed that households that enjoyed food security consumed an average of 16 different food items over 24 hours, whereas poorer households spent less money on food and consumed fewer than 8 different food items. Moreover, children had low mean scores for dietary diversity (3.58; standard deviation, SD: ± 1.37) and dietary variety (5.52; SD: ± 2.54) scores. In terms of food utilization, the NFCS showed that stunting in children decreased from 21.6% in 1999 to 18% in 2005. CONCLUSION The South African government must implement measures to improve the undesirably high level of food insecurity in poorer households.

Prevalence and determinants of stunting and overweight in 3-year-old black South African children residing in the Central Region of Limpopo Province, South Africa

OBJECTIVES To determine the prevalence of stunting, wasting and overweight and their determinants in 3-year-old children in the Central Region of Limpopo Province, South Africa. DESIGN Prospective cohort study. SETTING Rural villages in the Central Region of the Limpopo Province, South Africa. SUBJECTS One hundred and sixty-two children who were followed from birth were included in the study. Anthropometric measurements and sociodemographic characteristics of the children were recorded. RESULTS Height-for-age Z-scores were low, with a high prevalence of stunting (48%). The children also exhibited a high prevalence of overweight (22%) and obesity (24%). Thirty-one (19%) children were both stunted and overweight. Gaining more weight within the first year of life increased the risk of being overweight at 3 years by 2.39 times (95% confidence interval (CI) 1.96-4.18) while having a greater length at 1 year was protective against stunting (odds ratio (OR) 0.41; 95% CI 0.17-0.97). Having a mother as a student increased the risk for stunting at 3 years by 18.21 times (95% CI 9.46-34.74) while having a working mother increased the risk for overweight by 17.87 times (95% CI 8.24-38.78). All these factors also appeared as risks or as being protective in children who were both overweight and stunted, as did living in a household having nine or more persons (OR 5.72; 95% CI 2.7-12.10). CONCLUSION The results of this study highlight the importance of evaluating anthropometric status in terms of both stunting and overweight. Furthermore, it is important to realise the importance of normal length and weight being attained at 1 year of age, since these in turn predict nutritional status at 3 years of age.

Diet and mortality rates in Sub-Saharan Africa: Stages in the nutrition transition

BackgroundDuring the last century we have seen wide-reaching changes in diet, nutritional status and life expectancy. The change in diet and physical activity patterns has become known as the nutrition transition. At any given time, a country or region within a country may be at different stages within this transition. This paper examines a range of nutrition-related indicators for countries in Sub-Saharan Africa (SSA) and attempts to develop a typical model of a country in transition.MethodsBased on the availability of data, 40 countries in SSA were selected for analysis. Data were obtained from the World Health Organisation, Demographic and Health Surveys and the Food and Agriculture Organisation of the United Nations. Multiple linear regression analysis (MLRA) was used to explore the determinants of infant mortality. A six point score was developed to identify each countrys stage in the nutrition transition.ResultsMLRA showed that underweight-for-age, protein and the percentage of exclusively breastfed infants were associated with the infant mortality rate (IMR). The majority of countries (n = 26) used in the analysis had nutrition transition scores of zero and one. Most of them had a high prevalence of infant mortality, children that were stunted or underweight-for-age, small percentages of women that were overweight and obese, and low intakes of energy, protein, and fat. Countries with the highest scores include South Africa, Ghana, Gabon, Cape Verde and Senegal which had relatively low IMRs, high levels of obesity/overweight, and low levels of underweight in women, as well as high intakes of energy and fat. These countries display classic signs of a population well established in the nutrition-related non-communicable disease phase of the nutrition transition.ConclusionsCountries in SSA are clearly undergoing a nutrition transition. More than half of them are still in the early stage, while a few have reached a point where changes in dietary patterns are affecting health outcomes in a large portion of the population. Those in the early stage of the transition are especially important, since primordial prevention can still be introduced.

Obesity and the nutrition transition in Sub-Saharan Africa

This review illustrates the outcomes of the nutrition transition in Sub‐Saharan Africa (SSA) and its association with overweight and obesity; the relationship with the double burden of malnutrition is also explored. We describe the increase in overweight in nearly all Sub‐Saharan African countries and present data on associated increased gross domestic product, and availability of energy, protein, fat, and sugar at country national levels. Predictors of overweight are described by means of various studies undertaken in SSA, and dietary intakes of numerous countries are presented. Overall, we show that socioeconomic status, gender, age, parity, physical inactivity, and increased energy, fat, and sugar intake are powerful predictors of overweight and/or obesity. The urgency for health interventions in countries in the early stages of the nutrition transition is emphasized, particularly in view of the fact that fat intake is still less than 30% of energy intake in nearly all Sub‐Saharan African countries.

Estimating the burden of disease attributable to excess body weight in South Africa in 2000

OBJECTIVE To estimate the burden of disease attributable to excess body weight using the body mass index (BMI), by age and sex, in South Africa in 2000. DESIGN World Health Organization comparative risk assessment (CRA) methodology was followed. Re-analysis of the 1998 South Africa Demographic and Health Survey data provided mean BMI estimates by age and sex. Population-attributable fractions were calculated and applied to revised burden of disease estimates. Monte Carlo simulation-modeling techniques were used for the uncertainty analysis. SETTING South Africa. SUBJECTS Adults >or= 30 years of age. OUTCOME MEASURES Deaths and disability-adjusted life years (DALYs) from ischaemic heart disease, ischaemic stroke, hypertensive disease, osteoarthritis, type 2 diabetes mellitus, and selected cancers. RESULTS Overall, 87% of type 2 diabetes, 68% of hypertensive disease, 61% of endometrial cancer, 45% of ischaemic stroke, 38% of ischaemic heart disease, 31% of kidney cancer, 24% of osteoarthritis, 17% of colon cancer, and 13% of postmenopausal breast cancer were attributable to a BMI >or= 21 kg/m2. Excess body weight is estimated to have caused 36,504 deaths (95% uncertainty interval 31,018 - 38,637) or 7% (95% uncertainty interval 6.0 - 7.4%) of all deaths in 2000, and 462,338 DALYs (95% uncertainty interval 396,512 - 478,847) or 2.9% of all DALYs (95% uncertainty interval 2.4 - 3.0%). The burden in females was approximately double that in males. CONCLUSIONS This study shows the importance of recognizing excess body weight as a major risk to health, particularly among females, highlighting the need to develop, implement and evaluate comprehensive interventions to achieve lasting change in the determinants and impact of excess body weight.

How diverse is the diet of adult South Africans

BackgroundThe objective of the current study was to measure dietary diversity in South Africans aged 16 years and older from all population groups as a proxy of food security.MethodsA cross-sectional study representative of adults from all specified ages, provinces, geographic localities, and socio-economic strata in South Africa was used (n = 3287). Trained interviewers visited participants at their homes during the survey. Dietary data was collected by means of a face validated 24 hour recall which was not quantified. A dietary diversity score (DDS) was calculated by counting each of 9 food groups. A DDS <4 was regarded as reflecting poor dietary diversity and poor food security.ResultsThe provinces with the highest prevalence of poor dietary diversity (DDS <4) were Limpopo (61.8%) and the Eastern Cape (59.6%). By contrast, only 15.7% of participants in Western Cape had a low score. Participants in tribal areas (63.9%) and informal urban areas (55.7%) were by far the worst affected. There were significant differences in DDS by Living Standards Mean (LSM) analysis (p < 0.05) with the lowest LSM group having the lowest mean DDS (2.93).The most commonly consumed food groups were cereals/roots; meat/fish; dairy and vegetables other than vitamin A rich. Eggs, legumes, and vitamin A rich fruit and vegetables were the least consumed.ConclusionOverall the majority of South Africans consumed a diet low in dietary variety. The tribal areas and informal urban areas were worst affected and eggs, legumes and vitamin A rich fruit and vegetables, were the least consumed.

Evidence to support a food-based dietary guideline on sugar consumption in South Africa

Since 1997, South Africa has been developing and implementing food-based dietary guidelines for people aged >6 years. The complexity of the population, which contains different ethnic groups, as well as the rapid urbanization that is taking place, means that food-based dietary guidelines need to consider both overnutrition and undernutrition. The initial guidelines did not include guidance on sugar, and the Department of Health was not prepared to approve them until appropriate guidance on sugar was included. This paper summarizes the evidence available for such a guideline and the nature of that evidence. Other low- and middle-income countries, particularly those in Africa, may face a similar dilemma and might learn from our experience.