Jul 1, 1988 - http://sabinet.metastore.ingenta.com/content/m_samj/73/11/ ... Source : South African Medical Journal, Volume 73, Issue 11, Jul 1988, p. 643 - ...
SAMJ
VOL 73
4 JUN 1988
643
Nutritional status, dietary intake and disease patterns in rural Hereros, Kavangos and Bushmen in South West Africa/Namibia S. J. D. O'KEEFE,
J. E. RUND,
N. R. MAROT,
Summary A survey of Hereros, Kavan'gos and Bushmen living in the rural districts of South West Africa/Namibia was undertaken in order to assess their dietary' intakes, nutritional status and disease patterns. The results showed that Hereros were taller and heavier, with the highest incidence of obesity (15-30%) and hypertension, Their diet consisted chiefly of refined maize meal supplemented with sour milk, and their blood lipid levels were generally lower than Western standards. The diet of Kavangos, based on homeground millet supplemented with fish and fresh vegetables, was better balanced. However, malnutrition was more common particularly in hospital patients where 40% had infective disease, Finally, the diet of Bushmen was extremely poor consisting of whatever was available (generally maize meal) and excessive use of home-brewed alcohol. The majority were malnourished and 73% of those hospi-. talised had tuberculosis. The blood lipid levels of Bushmen and Kavangos were exceptionally 'favourable' by Western standards but associated with chronic malnutrition. The survival of Bushmen in modern society is a matter of grave concern. S Air Med J 1988; 73: 643-648.
In recent studies we have shown wide variations in the nutritional status of the different racial groups in South Africa with strong associations between nutrition and disease. For example, obesity was extremely common among urbanised Zulu women in Natal and was associated with a high prevalence of hypertension and cardiovascular accidents. 1 On the other hand, nutrient depletion was common among rural men and was frequently associated with infective disease, in particular tuberculosis. 2 A dietary survey of rural Zulus in Natal and KwaZulu revealed that their diet consisted mainly of refilled maize-meal taken three times a day with little supplementation with meat
Gastro-intestinal Clinic, Groote Schuur Hospital and University of Cape Town . S. J. D. O'KEEFE, M.D.,M.SC.,M.RC.P. J. E. RUND, B.Sc. HONS N. R. MAROT, M.B. CH.B. K. L. SYMMONDS, RN.,RM. Department of Chemical Pathology, Red Cross War Memorial Children's Hospital, Cape Town G. M. B. BERGER, B.SC.MED., M.B. CH.B., PH D. Accepted 10 Dec 1987.
K. L. SYMMONDS,
G. M. B. BERGER
and vegetables. 3 Consequently the dietary composlUon was high in carbohydrates and low me.at and dairy products. As a result the cholesterol content of the diet was also low and was reflected by very low plasma cholesterol and low-density lipoprotein cholesterol (LDL-C) concentrations. 4 Our results therefore suggested that the low cholesterol diet was at least partially responsible for the low incidence of ischaemic heart disease in rural blacks. Because of the refined nature of the diet, fibre intake was also surprisingly low and less than that now recommended by authorities in the West. Little is known of the general nutritional state of the various ethnic groups within South West AfricaINamibia. The greater part of the country is arid and the rate of evaporation exceeds that of annual rainfall so that agricultural foods carmot be produced. The situation has been worsened by the recent series of severe droughts accompanied by overgrazing and bush encroachment. One of the major black tribal groups are the Hereros. They are a Bantu race and occupy the central areas of the territory where rainfall varies between 200 mm and 400 mm per year insufficient to support crops so that agriculture is not practised and stock-farming (cattle and goats) is the traditional way of life. Their traditional diet, therefore, consists of high intakes of meat and dairy products. On the other hand, the Kavangos also Bantu - live in the far north where rainfall is substantial (> 750 mm per year) and the Okavango River supplies water all the year round; traditionally they rely on agriculture and are self-sufficient in their staple diet of 'African millet' augmented by fish from the river. It is well balanced - not unlike the modern 'prudent' diet. Finally, the Bushmen are scanered over large areas of the north-east and although they are traditionally" hunter-gatherers, the division of land, worsening of drought and the scarcity of wild game has resulted in a complete change of lifestyle and their absorption into the black communities and white farmlands. A study was undertaken to investigate the influence of the different dietary practices .and changes in lifestyle on the nutritional status and disease panerns of the three abovementioned groups.
Subjects and methods The area of the survey included Hereroland and Kavangoland and could be divided into two pans - a rural srudy of the normal population and a hospital srudy of the sick.
Rural studies Rural villages accessible by four-wheel drive vehicle were selected from ordinance survey maps of Hereroland and Kavangoland. Villages surveyed in Hereroland were Okakarara, Otumborombonga, Otjinene and Otijituo and in Kavangoland, Rundu, Andara and Bagani.
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The Bushmen included in the survey were predominantly from the Otjinene district of East Hereroland. The majority (80%) worked for and lived with Hereros, while a minority worked on neighbouring white farms. Permission was initially obtained from the local administrator or village headman before a hut-to-hut survey was undertaken. Included in the study were all adults over the age of 18 years. Anthropometric measurements were taken on each individual. A dietary questionnaire was then completed by the survey dietician with the assistance of local interpreters. Finally, at the end of the interview informed consent was obtained for the taking of blood samples. A total of 66 Hereros, 51 Bushmen and 41 Kavangos were assessed in this way.
Hospital studies The hospital study consisted of an anthropometric survey of all adult occupants of general medical and surgical wards on that particular day. All the hospitals were state-funded and served the local (black) populations. The hospitals surveyed in Hereroland were at Okakarara, Otjiwarongo and Grootfontein and the ones in Kavangoland were at Rundu and Andara Mission. The relatively small number of Bushmen patients were seen at Okakarara, Grootfontein and Rundu Hospitals. In all, the hospital survey included 85 Hereros, 94 Kavangos and 30 Bushmen.
Anthropometric measurements Height, without shoes, was taken with a portable vertical measure. Weight was measured by a bathroom scale, which was recalibrated each morning before the study continued (duplicate variation was less than 1%). Triceps skinfold thickness (TSF) ~easurements were taken with standard calipers. Mid upper-arm circumference measurements (MUAC) were used to calculate mid-arm muscle circumferences (AMC) from the formula: AMC = MUAC - (TSF x 3,14).
Standards and definitions of depletion The results of the anthropometric measurements were evaluated either by comparison with internationally accepted standards or by use of the body mass index (BMI) (reference range: men 20 -25 kg/m 2 , women 19 - 24 kg/m 2 ): body weight depletion = BMI < 17; obesity = .BMI > 30; fat depletion = TSF 60% standard; and muscle depletion = AMC < 80% standard.
Blood tests Tw.o samples :vere taken; 10 ml was transported in heparinised contaIners for bIochemical analysis while 5 ml was collected in ethylene diarnine tetra-acetic acid tubes for blood count determination. Biochemical samples were transported on ice to the local laboratory where the plasma was separated into two fractions. Samples for blood lipids (2 ml plasma) were 'flash frozen' and tran.sported in ~iquid ~itrogen. The remainder was deep-frozen to aWaIt routIne bIochemIcal analysis in Cape Town.
Dietary intakes A standardised dietary intake frequency question,naire' was used and completed by the survey dietitian with the assistance of a local Interpreter. Results were generally expressed in mean intake frequencies. Some difficulties were encountered with regard to the ass~ssment of sea~onal intakes. For examp1e, more vegetables, fr~llts and fresh mIlk were consumed by Hereros during the short raIny season (November - March). On the other hand, the diet of ma~y .B.ushmen vari.ed co.nsiderably depending chiefly upon availabIlIty. Aft~r the Inter:'Iews, cooking areas were inspected and local food, cooking and eatIng practices were documented. Statistics. The significance of differences between the three population groups was evaluated by Student's independent r-test.
Sample analysis Blood samples. Haemoglobin concentrations and biochemical profIles were measured in the routine Groote Schuur Hospital laboratories using standard multichannel auto-analysis. Blood lipids. All lipid assays were performed on thawed heparinised plasma which had been stored frozen pending analysi~ as .descnbed above. ~otal cho~esterol was estimated enzymatically USIng a commercIal kit (Boehringer-Mannheim CHOD-PAP highper~o~mance ki~). T?glyceride was also determined using a kit (C:lImcal 500 mmoVI) in 15% of Bushmen, 11% of Hereros and 4% of Kavangos.
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Rural people Hereros Men (N= 31) Female (N= 35) Bushmen Men (N= 26) Women (N= 25) Kavangos Men (N= 19) Women (N = 22) Hospital patients Hereros Men (N= 48) Women (N = 37) Bushmen Men (N= 12) Women (N= 18) Kavangos Men (N= 55) Women (N = 39)
0/0 weightdepleted
0/0 obese
0/0 fatdepleted
19 6
17 32
48 17
0 4
15 52
0 0
70 76
7 32
16 9
0 0
63 41
5 5
33 14
0 11
69 18
23 10
44 55
0 0
100 72
44 61
42 18
0 0
78 49
25 17
TABLE Ill. SUMMARY OF BLOOD TEST RESULTS (GROUP MEAN SUBJECTS Control range Ferritin (JL91I) Men Women Haemoglobin (g/dl) Men Women Vitamin A (JLg/ml) Men Women
20 - 220 20 - 220 13,3 - 17,3 11,6-15,6 >30 >30
645
Low plasma albumin concentrations were uncommon. However, 16% of Bushmen and 13% of Herero patients had levels below the control range (i.e. < 35 g/I). Vitamin A deficiency, defined by low plasma concentrations, was observed in 14% of Bushmen but was uncommon in the other rwo groups. The cholesterol parameters of the three groups are shown in Table IV and are compared with the adult mean vaiues for the Lipid Research Clinic's programme. 8 Since total cholesterol and LDL-C values are age-dependent, the mean ages are also given. These were comparable for the Kavangos and Bushmen. The Hereros, notably the Herero men, were berween 5 and 10 years older than the other rwo groups. HDL-C levels in most populations are higher in women than in men but this sexual dimorphism has not been observed in all populations. 9 Within the limits of the relatively small numbers examined, the Kavango men and Bushmen men had substantially lower LDL-C levels than did Herero men and much higher HDL-C concentrations. Furthermore, in the Kavango and Bushmen groups, the.sexual dimorphism of HDL-C levels was entirely absent; if anything, the HDL-C levels were slightly higher in the male subjects compared with the women. The Hereros, in turn, had total cholesterol values very similar to the Lipid Research Clinic data given in Table IV. However, LDL-C levels were somewhat lower and HDL-C levels were
TABLE 11. PROPORTION OF RURAL AND HOSPITALISED PERSONS NUTRITIONALLY DEPLETED OR OBESE Population group
4 JUN 1988
Hereros
±
0/0 muscledepleted
SD) IN RURAL
Bushmen
Kavangos
± 241 ± 138
201 243
± 135 ± 176
198 ± 132 174 ± 119
13,9 ± 2,5 12,3 ± 2,2
13,1 12,1
± 2,7 ± 2,5
12,2 11,3
± 2,6 ± 2,3
57,2 58,2
± 23,0 ± 18,6
61,5 58,9
± 24,2 ± 32,7
264 222
62,2 51,8
± 31,3 ± 16,5
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observed to be still intoxicated during Monday morning surveys. The staple diet of Hereros and Bushmen was refined maize meal 2-3 times per day, i.e. similar to that of Zulus. However, Kavangos produce and prepare their own staple - African millet - which is consequently a whole grain product. Bread is taken daily by the wealthier members of each community - in particular Hereros but uncommonly by Bushmen apart from those living on white farms. Fresh milk was taken daily by Hereros during the summer rainfall season. Otherwise sour milk was either purchased or home produced. Meat, either fresh or tinned, was taken 2-3 times a week by Hereros but rarely by Kavangos, Bushmen and Zulus. Fish (tilapia and tiger fish) was more commonly eaten by Kavangos, but intakes were still low at approximately 7-8 times per month. Eggs were eaten 3-4 times a week by Hereros and fresh milk was hardly ever consumed by Kavangos. Animal fat (lard), sour-milk curds and salt were used liberally by Hereros to flavour refined maize-meal porridge. Vegetable intake was seasonal (i.e. during the rains) in Hereros and Bushmen and consisted of leafy plants and berries. A more regular annual intake was observed in Kavangos. Little use of beans was seen in any of the three communities. In conclusion, the overall diet was high in carbohydrates. Meat and dairy product use was far more common in Hereros but still low by white South African standards. Vegetable intake was poor in Hereros and Bushmen, especially in the dry season. Consequently, Kavangos consumed the traditional African high-fibre diet while Hereros and Bushmen now have a low-fibre intake similar to that of modem Zulus. Finally, strong evidence of severe dietary imbalance was obtained in the Hereroland Bushmen.
somewhat higher than those observed in a well-srudied Western population. Excluded from Table IV are individuals with incomplete lipid results or values far outside the 5th or 95th percentile limits. These may have reflected either major genetic variations or severe malnutrition or other debilitating diseases. Thus, the values shown in Table IV are fairly conservative estimates of the population distribution. Triglyceride levels, less relevant to considerations of atherosclerotic risk, are biologically more variable than cholesterol values and are influenced by dietary intake in a manner difficult to control in a survey of this narure. The results obtained on the three groups were more or less similar and did not differ significantly from those of the Lipid Research Clinic's population.
Dietary intake patterns The dietary intake frequency is shown in Table V and is compared with that of east coast South African Zulus. 3 While the diet of Hereros and Kavangos was reasonably constant, that of Bushmen was not and therefore does not lend itself to tabulation in the form of the frequency chart (Table V). For example, .Bushmen who worked on white-owned farms related similar dietary intakes to Hereros, while those who worked in Herero villages and farms had extremely poor, irregular intakes of 'whatever was available'. For the majority of men, this consisted almost exclusively of maize-meal porridge in one form or another, black tea and home-brewed beer. Beer consumption was particularly excessive at weekends in quantities up to 5 Vd and many of the men were
TABLE IV. BLOOD LIPID CONCENTRATIONS (GROUP MEAN ± SO) IN RURAL HEREROS, KAVA NGOS AND BUSH MEN Group
Age (yrs)
Total cholesterol
LDL-C (mmol/I)
HDL-C (mmol/I)
Triglyceride
42,6 45,9 39,6
5,02 ± 1,06 4,96 ± 1,37 5,08± 0,71
3,00 ± 1,02 3,07 ± 1,26 2,93 ± 0,79
1,44 ± 0,43 1,27 ± 0,31 1,59 ± 0,47
1,30 ± 0,69
34,5 33,4 36,2
4,24 ± 0,63 4,01 ± 0,62 4,59 ± 0,50
1,86 ± 0,74 1,53 ± 0,46 2,35 ± 0,83
1,77 ± 0,66 1,80 ± 0,64 1,73 ± 0,75
1,33 ± 0,82
35,5 35,1 38,8
4,47 ± 0,82 4,46 ± 0,90 4,49 ± 0,76
2,30 ± 0,74 2,18 ± 0,77 2,42 ± 0,71
1,63 ± 0,41 1,76 ± 0,49 1,50 ± 0,28
1,18 ± 0,66
5,04 4,98 5,10
3,26 3,28 3,25
1,33 1,18 1,49
1,30
Hereros Total (N= 54) Men (N= 25) Women (N = 29) Kavangos Total (N= 15) Men (N= 9) Women (N= 6) Bushmen Total (N= 32) Men (N= 16) Women (N= 16) Reference pop. * Total Men Women
... Reference values obtained from US Lipid Research Clinics data. 6
TABLE V. RESULTS (MEAN
± SO) OF DIETARY FREQUENCY QUE~mONNAIRE
Food constituent
Hereros
Kavangos
Bushmen*
Zulus3
Maize mealld Millet/d Bread/d Vegetables/mo. Fresh milk/mo. Sour milk/mo. Meat/mo. Fish/mo. Eggs/mo. Beans/mo. Rice/mo.
2,2 ± 1,0
t
2,4 ± 1,0
2,5 ± 0,6
1,3±1,3 8,5 ± 14 7,9 ± 2,6 37,0 ± 36,0 17,4 ± 35 0,8 ± 1,7 14,9 ± 29 3,4 ± 6,5 5,2 ± 9
2,4 ± 0,6 0,6±1,1 26 ± 5,0 0,4 ± 0,4 2,4 ± 0,7 3,8 ± 2,9 7,6 ± 10,3 1,3 ± 2,8 3,0 ± 3,7 3,0 ± 9,5
t
3,1
± 9,0
t t t t t
1,9 ± 2,4
... Data on Bushmen irregular and variable making accurate group analysis impossible (see text). t Generally insignificant intakes.
0,9 ± 22,3 ± 1,6 ± 4,5 ± 3,5 ± 3,2 ± 2,8 ± 2,6 ± 1,3 ±
0,4 11 4,3 7,2 4,5 5,0 4,8 4,7 3,4
SAMJ
Disease patterns A summary of the most important disease patterns is shown in Fig. 1. A high incidence of acute infection was seen in Bushmen (80%) and Kavangos (55%) and rather less in Hereros (22%). Tuberculosis was the most important cause accounting for over 80% of infections in Bushmen and in 50% of the other two groups. On the other hand essential hypertension was common in Herero patients (20%).
H=HERERO
B=SUSHMEN K=KAVANGO
SURGICAL/ TRAUMA HYPERTENSION
20
1
·TB·
10
·TB·
o ... H
B
K
H
B
K
H
B
K
Fig. 1. Some of the chief differences in disease patterns in the three different populations studied.
Nutritional depletion was especially common in patients with tuberculosis; for example 57% were significantly weight depleted, none were obese, 80% were fat depleted and 45% were muscle depleted. In contrast only 18% of hypertensive patients were found to be weight depleted while 28% of them were obese.
Lifestyle Major differences in lifestyle and physical activity were particularly noted between the women of the three groups. Herero women appeared to be the least physically active and spend the major part of the day sirting aroung the cooking areas looking after young children. In contrast, Kavango women were far more active being involved in local agriculture and fishing. Not only do they grow their own staple food mahongo (Mrican millet) but they also thrash, grind and sieve the grain. Activity levels in female Bushmen were intermediate.
Discussion The findings of the survey highlight some important variations in the dietary habits, nutritional status and disease patterns in rural blacks. Anthropometric measurements showed that Hereros are a tall race, on average taller than South Mrican ZuIUS. I ,3 The pattern of obesity in women was very similar to that in Zulus and was probably related to the high carbohydrate diet and low level of physical activity. Hereros are pasturalists, the men looking after the stock while the women are sedentary. Since agriculture· is not practised, the staple diet, refined maize meal, is purchased in bulk from district stores. Although it is generally believed that Hereros eat vast quantities of beef and dairy products, we found this, as a generalisation, to be a misconception. Certainly, the consumption rate was higher than in the other two groups studied, but was still low by Western standards. Similarly. blood cholesterol concentrations
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were also higher than in the other two groups and also higher than those previously reported in rural Zulus. 3 The levels are very similar to the Lipid Research Clinics population (Table IV) but are lower than those of age-matched white South Africans. 4 Interestingly, the cholesterol levels found in the survey in Hereros were remarkably similar to those reported in Ovambos, their black (Bantu) neighbours, by Watermeyer and Mann 10 in 1972. In a comparative analysis they found that cholesterol concentrations were higher in Ovambo men than in other rural groups such as Pondos and Bushmen, but were considerably lower than those of white office-workers. It thus appears ·that there has been little change in the blood lipid concentrations of black adults in northern South West Africa! Namibia over the past 15 years. While total cholesterol levels in the Hereros were fairly similar to an age-matched Lipid Research Clinics (USA) population, the LDL-C levels were lower and the HDL-C values were higher, which reflects a better atherosclerotic risk ratio. Coronary artery disease rerI;ains rare and no case was detected in this hospital survey. On the other hand, hypertension is a common disease in Hereros and .was seen in 20% of Herero patients. In common with previous findings in Zulus, 1 it is likely that obesity was the major cause of hypertension. Salt and fat intakes were not shown to be excessive. Another possible aetiological factor is the low intake of potassium-rich foods, e.g. vegetables. Indeed the intake of fresh foods was so poor that it was surprising that no clinical signs of vitamin deficiencies were seen in hospitalised patients. While the full screen of blood vitamin levels was not performed, biochemical. vitamin A deficiency was rare in the rural inhabitants sampled. The situation in Kavangos was different in many ways. They are smaller in stature than Hereros and obesity was far less common in women and not seen in men. Their diet was quite different, the staple, mahongo or Mrican millet, was home-grown and processed. Vegetable intake, chiefly in the form of melons, squashes and green leaves, were also homegrown and available year round because of the abundant water supply. The river also provided fish, which were caught with homemade flask nets and nylon barrier nets. Consequently, the Kavangos lead considerably more active lives than Hereros, and their diet is very close to that advocated by Western nutrition authorities, i.e. the 'prudent' diet. The plasma lipid profile of the Kavangos, like the Bushmen, differed substantially from that of the Hereros with much lower LDL-C and total cholesterol values and higher HDL-C levels. These differences were most striking in the men whose HDL-C levels were actually slightly higher than that of the female subjects (1,80 mmol/l v. 1,73 mmol/l respectively). None of the Kavangos had LDL-C levels above the 95th percentile and only 2 of the 15 had LDL-C levels which fell into an increased-risk range compared with 70 - 80% of a normal Western population. In th.e male Kavangos the HDL-C level exceeded the LDL-C concentration, a relationship normally observed in newborn infants in Western countries. Omitted entirely from consideration are 3 Kavangos (2 men and 1 woman) with grossly reduced LDL-C levels (less than 1,0 mmol/l) for undetermined reasons. Despite these positive features there was little evidence that they were healthier than Hereros - or Zulus. Malnutrition was significantly more common in hospital patients, as was the incidence of infectious disease (mainly tuberculosis). The high incidence of eye infections in children and corneal scarring in adults was noteworthy, despite relatively normal plasma vitamin A concentrations. These findings illustrate the complex interrelationship between nutrition and health and emphasise the fact that nutrition is but one of the factors important in the maintenance of good health. For example, tropical diseases and parasitic infections are far more common in the high rainfall areas of Kavango than the dry semi-desert areas of Hereroland.
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Finally, we come to the Bushman. Until relatively recently, he has survived as the last hunter/gatherer in the southern Mrican subcontinent leading a nomadic existence over wide expanses of semi-desert in South West Mrica/Namibia and Botswana. However, this traditional· way of life has been jeopardised by the need to develop the land for agricultural and stock-farming purposes. Fencing and the division of the land has indirectly led to a drastic reduction in the wild animals on which he depl'mds, for migration is essential for their survival in times of drought. The situation has been exacerbated by the recent series of severe droughts and more and more Bushmen have had to seek refuge in the nearest black villages and white towns. Bushmen encampments consisting of small, roughly constructed canopies of branches and thatch - are evident in most such villages in Hereroland and Kavangoland today. Here they can obtain water and food in exchange for servitude, since they are ill-equipped to support an independent existence in modern society. As shown in this study, there was no anempt to gather traditional foods and they ate whatever was available. As maize meal is the cheapest and commonest food available, it constitutes almost the entire diet with the notable exception of beer. Their dependence on alcohol gives rise to extreme concern. Not only does it add to the imbalance of their diet, but it leads to further social disintegration. Thus it is not surprising that we found their nutritional status and health to be appalling. It was only in the Bushmen that we noted frank signs of vitamin deficiency, in particular, pellagra. We have previously described the strong association between malnutrition and tuberculosis in malnourished rural Zulus, and it came as linle surprise that nearly every Bushman seen in hospital was suffering from the ravages of pulmonary tuberculosis. Many consider the Bushmen a 'dying' race. Support for this suggestion was found in our observation that the best off were those who had become individually integrated into the black communities or white farmlands. Anempts have been, and still are, made to resenle them in 'Bushmanland'. However, a recent survey indicated that only 7% of the total Bushman population live within this area and resettlement is commonly resisted. I I The question is, should they be allowed to slowly fade out and become absorbed into the local black population or should major communitybased efforts be made to reconstruct the fabric of their society? These questions are ultimately political, but it is our duty as doctors and health workers not only to treat the consequences in hospital, but also to apply preventative measures within the community at large. The Bushmen's lipid profile was essentially similar to that of the Kavangos. They included 2 male Bushmen with abnormally reduced LDL-C levels and, interestingly, 1 l6-year-
old woman with a substantially high total cholesterol level strongly suggestive of familial hypercholesterolaemia (total cholesterol 8,22 mmol/l; LDL-C 6,56 mmol/l; HDL-C 1,09 mmol/l; triglyceride 1,24 mmol/l). This subject, as well as those with grossly reduced values, was excluded from Table IV. The blood lipid profile of Bushmen was essentially similar to that of the Kavangos. It is reasonable to conclude that the Bushmen and Kavangos differ considerably from Herero people and from industrialised populations in having a well-nigh perfect anti-atherosclerotic risk profile. However, since this was associated with a high incidence of undernutrition and infectious disease in the community it should, perhaps, be used as a warning against the recommendaton of extreme lipidmodifying diets to the general population of Western countries.
We would like to thank Dr Rodion Krause and the South West Mrican Department of Health and Welfare, Windhoek, South West Mrica/Namibia, and Dr A. Burger, Director of Hospital Services, Kavango Province, for permission to conduct the surveys. We are also grateful for the assistance provided by Dr P. vari Rensburg, Okakarara Hospital; Sister Agnes Ward, Otjinene Clinic; and Father Kapp, Andara Hospital. We acknowledge the technical assistance with blood sample analysis of Professor P. Jacobs and Dr J. Graves, Department of Haematology, Groote Schuur Hospital, and also Dr D. Labadarios of the Metabolic Unit, Tygerberg Hospital, for the vitamin analysis.
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