Johanna H. Nel

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.

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.

Evaluation of Body Shape, Eating Disorders and Weight Management Related Parameters in Black Female Students of Rural and Urban Origins:

This study examined body shape dissatisfaction, eating disorder and weight management-related parameters as well as assimilation of Western cultural norms regarding body shape in black female students of urban and rural origins. Subjects (n=180; 20 ± 4,4 years old) were weighed, their height was measured and they completed the Body Shape Questionnaire, EAT-26, Eating Inventory (restraint scale), Adolescent Self-Concept Scale and a questionnaire concerning weight management behaviours. Main findings include lower prevalences of overestimation of body weight and body shape dissatisfaction, similar prevalences for dieting and the use of Hazardous weight reduction methods, and higher prevalences for overweight, obesity, disordered eating attitudes and behaviours, and dietary restraint among subjects than among similar white groups. Furthermore, those with urban origins were more likely to be restrained eaters, to have attempted weight reduction, to aim for weight loss and to fear weight gain. These data indicate that there are signs of more realism concerning weight status among black female students. However, there are also signs of assimilation of Western cultural norms concerning body shape, eating attitudes and behaviours and weight management. This diversity in the black student population in South Africa needs to be recognized when planning interventions to address eating related problems.

Secondary data analyses of dietary surveys undertaken in South Africa to determine usual food consumption of the population.

OBJECTIVE The primary objective of this study was to generate a reference table of food items and average amounts of these items consumed by South Africans, for the Department of Health. The reference table was required to be representative of foods and beverages eaten frequently by children and adults from all age and ethnic groups in order for the Department of Health to test for contaminants in these foods. DESIGN The National Food Consumption Survey (NFCS) served as a framework for compiling data on children since this was a national representative survey of 1-9-year-old children undertaken in South Africa in 1999. However, there has never been a national dietary survey on adults in South Africa. Consequently the data had to be extrapolated from existing isolated surveys on adults. Secondary data analysis was conducted on existing dietary databases (raw data) obtained from surveys undertaken on adults in South Africa between 1983 and 2000. Available datasets were regional and independent, and were not individually representative of the South African diet. It was therefore necessary to use different statistical methods, including factor analyses, weighting and correlations, to generate ethnic and geographic representative data for adults. Two methods were used: Method 1, which corresponded with results of the NFCS (over-sampled for low socio-economic status), and Method 2, which was based on ethnic proportions of the population. RESULTS The secondary data analyses generated food items most commonly consumed by the South African adult population (Method 1) in descending frequency of usage and average (mean) amount per day: maize porridge (78%/848 g), white sugar (77%/27 g), tea (68%/456 g), brown bread (55%/165 g), white bread (28%/163 g), non-dairy creamer (25%/6 g), brick margarine (21%/19 g), chicken meat (19%/111 g), full-cream milk (19%/204 g) and green leaves (17%/182 g). In 6-9-year-olds, maize porridge (72%/426 g), sugar (76%/23 g), tea (51%/258 g), full-cream milk (35%/171 g) and white bread (33%/119 g) were eaten most frequently. Similarly, in 1-5-year-olds, the foods consumed most frequently were maize porridge (80%/426 g), sugar (76%/21 g), tea (44%/224 g), full-cream milk (39%/186 g) and white bread (24%/83 g). In order to evaluate the validity of the adult data generated, kilojoule values of the individual food items (per capita) were compared with food balance sheets (FBSs). The comparison was favourable except that the FBSs had a higher overall energy intake per capita of between 22 and 28%. CONCLUSION Reference tables of commonly consumed foods and beverages were generated at minimal cost based on secondary data analyses of past dietary surveys in different South African populations.

Dietary, social, and environmental determinants of obesity in Kenyan women

Aim: To assess the determinants of overweight and obesity in Kenyan women considered to be undergoing the nutrition transition. Methods: A nationally representative sample of women (n = 1008) was randomly drawn. Weight, height, waist, and hip circumference were measured. A 24-hour dietary recall was conducted with each participant and a socio-demographic questionnaire completed. Data was analysed by age, education, location, and socioeconomic status. Risk for obesity was calculated while adjusting for age and location. Results: Overweight and obesity (BMI ≥ 25 kg/m2) were highly prevalent in Kenya (43.3%). Urbanisation appears to be an important determinant of obesity since obesity was most prevalent in urban women in the high income group. Women in the high income group (7278 kJ) and in urban areas (7049 kJ) had the highest mean energy intakes. There were also significant urban/rural and income differences in the contribution of macronutrients to energy intake. Total fat intake was 34.5% of energy (E) in urban areas and 29.7% E in rural areas; while carbohydrates contributed 69.9% E in rural areas and 57.4% E in urban areas (p < 0.0001). Overweight was significantly more likely in the highest income group; among households where room density was low; electricity or gas was used for cooking; and households had own tap and/or own flush toilet. Conclusions: This study suggests that urbanisation and its associated economic advancement as well as changes in dietary habits are among the most important determinants of overweight and obesity in Kenyan women.

Development and validation of a short questionnaire to assess sodium intake

OBJECTIVES To develop and validate a short food-frequency questionnaire to assess habitual dietary salt intake in South Africans and to allow classification of individuals according to intakes above or below the maximum recommended intake of 6 g salt day-1. DESIGN Cross-sectional validation study in 324 conveniently sampled men and women. METHODS Repeated 24-hour urinary Na values and 24-hour dietary recalls were obtained on three occasions. Food items consumed by >5% of the sample and which contributed > or =50 mg Na serving-1 were included in the questionnaire in 42 categories. A scoring system was devised, based on Na content of one index food per category and frequency of consumption. RESULTS Positive correlations were found between Na content of 35 of the 42 food categories in the questionnaire and total Na intake, calculated from 24-hour recall data. Total Na content of the questionnaire was associated with Na estimations from 24-hour recall data (r = 0.750; P < 0.0001; n = 328) and urinary Na (r = 0.152; P = 0.0105; n = 284). Urinary Na was higher for subjects in tertile 3 than tertile 1 of questionnaire Na content (P < 0.05). Questionnaire Na content of <2400 and > or =2400 mg day-1 equated to a reference cut-off score of 48 and corresponded to mean (standard deviation) urinary Na values of 145 (68) and 176 (99) mmol day-1, respectively (P < 0.05). Sensitivity and specificity against urinary Na > or =100 and <100 mmol day-1 was 12.4% and 93.9%, respectively. CONCLUSION A 42-item food-frequency questionnaire has been shown to have content-, construct- and criterion-related validity, as well as internal consistency, with regard to categorising individuals according to their habitual salt intake; however, the devised scoring system needs to show improved sensitivity.

National fortification of staple foods can make a significant contribution to micronutrient intake of South African adults

BACKGROUND A national survey found that micronutrient deficiencies are prevalent in South African children, particularly calcium, iron, zinc, riboflavin, niacin, vitamin B6, folate, vitamin A, E and C. Mandatory fortification of maize meal and wheat flour were introduced in 2003 to combat some of the deficiencies found in children. To date however, there has not been a national survey on dietary intake in adults. OBJECTIVES The main objectives of this study were to evaluate the micronutrient intake of the diet consumed by the average adult South African by means of secondary data analyses and secondly to evaluate the effects of fortification on selected nutrient intakes. STUDY DESIGN Secondary data analysis was carried out with numerous dietary surveys on adults to create a database that included sampling (and weighting) according to ethnic/urban-rural residence in line with the population census, of which 79% were black Africans and the majority resided in rural areas. The effect of fortification was evaluated by substituting fortified foods in the diet for the unfortified products. SUBJECTS The combined database used in this study comprised 3229 adults. RESULTS Mean calcium, iron, folate and vitamin B6 intakes were very low particularly in women. Mean intakes of most micronutrients were lower in rural areas. Fortification of maize meal and wheat flour (bread) raised mean levels of thiamine, riboflavin, niacin, vitamin B6 and folate above the recommended nutrient intakes (RNIs). In women, despite fortification, mean iron intakes remained below the RNIs, as did calcium since it was not in the fortification mix. CONCLUSION The average dietary intake of adults was of poor nutrient density, particularly in rural areas. Fortification of maize meal and wheat flour (bread) considerably improved mean vitamin B6, thiamine, riboflavin, niacin, folate and iron intakes as well as the overall mean adequacy ratio of the diet.

Urbanisation and the nutrition transition: A comparison of diet and weight status of South African and Kenyan women

Aims: To determine and compare the extent of the nutrition transition between Kenyan and South African women. Methods: A nationally representative sample of women aged ≥15 years (n=1008) was assessed in Kenya. Weight, height, and waist and hip circumferences were measured. A 24-hour dietary recall was conducted with each participant. This data was compared with data of the Demographic and Health Survey (DHS) of women in South Africa (n=4481). Dietary intake of South African women was based on secondary data analysis of dietary studies using the 24-hour recall method (n=1726). Results: In South Africa, 27.4% women had a BMI ≥30 kg/m2 compared with 14.2% of Kenyan women. In both countries there were large urban–rural differences in BMI, with the highest prevalence in women in urban areas. BMI increased with age, as did abdominal obesity which was equally prolific in both countries with more than 45% of women in the older groups having a waist/hip ratio ≥0.85. The nutrient mean adequacy ratio (MAR) of the South African rural diet was lower than those of the Kenyans diet (55.9; 57.3%, respectively). Dietary diversity score (DDS) and food variety score (FVS) were significantly lower in South African rural women (3.3; 4.9) compared with Kenyans (4.5; 6.8). Conclusions: Urban–rural differences in diet and weight status indicates that the nutrition transition was similar in both countries despite large sociodemographic differences; however, rural Kenyan women had a better MAR, DDS, and FVS than South African women, most probably due to 60% having access to land.

Development of a novel nutrition screening tool for use in elderly South Africans

OBJECTIVE To develop a nutrition screening tool for use in older South Africans. DESIGN A cross-sectional validation study in 283 free-living and institutionalised black South Africans (60+ years). METHODS Trained field-workers administered a 24-hour recall and the Mini Nutritional Assessment (MNA) screening tool, and performed anthropometric measurements and physical function tests. Cognitive function was assessed using a validated version of the Six-Item Cognitive Impairment Test. Biochemical indicators assessed included serum albumin, haemoglobin, ferritin, vitamin B12, red-blood-cell folate, cholesterol and vitamin C. The MNA was used as the gold standard against which a novel screening tool was developed using a six-step systematic approach, namely: correspondence analysis; identification of key questions; determination of internal consistency; correlational analyses with objective measures; determination of reference cut-off values for categories of nutritional risk; and determination of sensitivity and specificity. RESULTS The new screening tool includes nine separate concepts, comprising a total of 14 questions, as well as measurement of mid-upper arm circumference. The new tool score was positively associated with level of independence in either basic activities of daily living (r = 0.472) or the more complex instrumental activities of daily living (r = 0.233). A three-category scoring system of nutritional risk was developed and shown to significantly characterise subjects according to physical function tests, level of independence and cognitive function. The new tool has good sensitivity (87.5%) and specificity (95.0%) compared with the MNA scoring system. It has a very high negative predictive value (99.5%), which means that the tool is unlikely to falsely classify subjects as well nourished/at risk when they are in fact malnourished. CONCLUSION A novel screening tool has been shown to have content-, construct- and criterion-related validity, and the individual items have been shown to have good internal consistency. Further validation of the tool in a new population of elderly Africans is warranted.