Alexander R. P. Walker

Iron “overload” in the South African Bantu

Summary (1) Among the South African Bantu, the intake of iron is often very high—as much as 200 mg. per diem. This high intake is due mainly to the uptake of the element from iron utensils occuring during the preparation of their usual foods (particularly fermented cereal products). (2) Published experimental evidence suggests that this level of iron intake is sufficiently high to overcome the “mucosal block” or the regulatory mechanism operating at everyday levels of intake, and allow unrequired iron to be absorbed, deposited and accumulated in the organs and tissues of the body. (3) Observations by several workers show that excessive deposition of iron does, in fact, occur frequently; and that the incidence, age and sex affected, the morbid anatomical distribution of the element, and other characteristics, are all such as might be predicted to arise from oral iron overload. (4) Although several conditions can cause or be accompanied by abnormal iron deposition—discussion suggests that intravenous iron, excessive destruction of erythrocytes, idiopathic haemochromatosis, and malnutrition, play little part in the siderosis observed in the Bantu. (5) It is submitted that the abnormal deposition of iron in these people is due primarily to their habitually high iron intake. No lesion of the digestive tract or any other organ need be invoked to account for it. Furthermore, there appears to be no evidence that iron overload per se is detrimental to well-being.

Breast cancer in black African women: a changing situation.

Black African women in rural South Africa have a very low incidence rate of breast cancer, 5-10 per 100,000. The rate, however, is rising in the considerably increasing urban population. During the period 1994 to 1999 in Durban, enquiries revealed an average of 57 urban patients admitted to hospital each year, from a population of about 600,000 African women, indicating an age-adjusted annual incidence rate of 15.1 per 100,000. This incidence rate is very low in comparison with those in developed populations, which range from 40 to 89 per 100,000. In the African patients studied, the mean age on admission was relatively young, 54.1±10.9 years, almost a decade earlier than patients of developed populations. Moreover, the disease was very far advanced; 21.1% were at Stage III and 63.1% at Stage IV. As to exposure to risk factors, African women in general are characterised by certain protective factors. These factors, which closely resemble those of importance in patients in developed populations are, late menarche, early age at birth of first child, high parity (with usually prolonged lactation), and being physically active. However, with ongoing changes in the lifestyle of urban African women, the protective factors are decreasing in their intensity. Changes in these respects have been associated with rises in the disease’s incidence rate. Clearly, because of the late stage of the disease at the time of the patients’ admission to hospital, and hence their poor survival rate, intensive efforts should be made to educate women to seek help at an early stage of their disease. For its avoidance, feasible protective or restraining measures are primarily to adopt a ‘prudent’ lifestyle, in respect of both dietary and non-dietary components. However, the chances of these measures being meaningfully adopted in African urban communities, unfortunately, are negligible. In consequence, further increases in incidence rate would seem inevitable.

The composition of breast milk of south African Bantu mothers

Abstract Two hundred and sixty-six samples of breast milk mainly from urban South African Bantu mothers have been analysed. In respect of total solids, ash, protein, fat, lactose, calcium and phosphorus, it has been found that mean valyes closely approximate to corresponding means given for the milks of British and American mothers. The composition of the milks does not appear to be influencd by the tribal group of the mothers, by their habitual diet (largely composed of maize, bread, legumes), nor by their nutritional state. Their capacity to breast-feed is almost invariable, moreover, impressions suggest that the yield is satisfactory at least for the first 6 months. It is submitted that either the role of diet in lactation is over-emphasized, or that the body has a greater capacity to adapt itself to an inferior diet than is usually accepted.

Editorial: Coronary Heart Disease. Limitations to the Application to White Populations of Lessons Learned from the Underprivileged

I N THE literature, at symposia, and on other occasions when the cause of coronary heart disease is discussed, it is sometimes said that if only people consumed the low-fat diet of the Bantu, coronary heart disease would no longer be the major public health problem which it now constitutes among white populations. This view contains a measure of truth. On the other hand, it is seldom appreciated that while the Bantu have negligible mortality from coronary heart disease, they suffer from other cardiovascular diseases which together exact a high toll of morbidity and mortality. It is, moreover, insufficiently appreciated that a low-fat intake is only one feature of the Bantu diet; and furthermore that in comparison with whites there are a number of differences in manner of life, metabolism, and other respects, whose influence on coronary heart disease, directly or indirectly, may well be considerable. Firstly, regarding heart diseases other than coronary heart disease, at Baragwanath NonEuropean Hospital (2,200 beds), Johannesburg, some proportions of the relevant admissions have been listed as follows: rheumatic heart disease (23.6 per cent), cor pulmonale (10.9 per cent), hypertensive heart

Fibrinolytic Activity of Whole Blood from South African Bantu and White Subjects

M ORTALITV fromn coronary heart disease is believed to be almost unknown among rural South African Bantu ; even among urban dwellers, deaths from the disease as proved at necropsy are extremely few.”2 Confirmation of this belief is being obtained from a collaborative clinical and biochemical study now in progress on Johannesburg Bantu pensioners over sixty years old (some approaching 100 years of age) ; in 340 subjects thus far examined, only one case of coronary heart disease, judged from clinical and electrocardiograph observations, has been detected.3 In the same number of elderly white people in Western countries, evidence suggests that fifty or more cases would be expected.4’ This favourable situation among the Bantu is far from explicable. Thus, while severe atherosclerosis of the aorta and, to much lesser extent, of coronary vessels is not common among them, unquestionably on occasion severe lesions do develop.6” Hypertension, moreover, is common #{149}6 .7 . 9 ,12, 13 Since these conditions, severe atherosclerosis and hypertension, are present in a proportion of adult Bantu, it would seem plausible from current thoughttm4” to consider that decreased coagulability and increase fibninolysin activity of blood may be among the salient factors that prevent the occurrence of acute thrombotic episodes in the coronary vessels of these people. Studies on Cape Town Bantu have revealed a deficiency

Long term investigation of blood loss and egg load in urinary schistosomiasis in the adult African Bantu

Abstract Eight adult Bantu males from Southern Africa were selected, suffering from very severe urinary schistosomiasis (verified by cystoscopy) with persistent obvious haematuria. Urine was collected continuously in 12-hour periods, six subjects for 10 days, and two subjects for 19 days. The following are the salient findings 1. (a) The colour of the urine is little guide to the amount of blood lost, and no guide to the number of eggs passed. 2. (b) The average amount of blood lost is smaller than was expected; it varied from 1.3 to 6.1 ml. per diem. The haemoglobin levels of six subjects lay within normal limits; lower values were obtained with the two remaining subjects, who, however, also suffered from malaria. It is concluded that in urinary schistosomiasis in adult Bantu males, the amount of blood lost is insufficient to cause hypochromic anaemia, but it might well aggravate an anaemia due to other causes. 3. (c) The number of eggs voided is subject to enormous fluctuation. One day there may be no eggs, and the next day tens of thousands. This irregularity once more draws attention to the unreliability of seeking to make a diagnosis of urinary schistosomiasis from single samples of urine.

The relationship between bowel cancer and fiber content in the diet

Colon cancer, very rare in rural South African blacks, is also rare in urban dwellers despite considerable rise in prosperity. The disease has scarcely increased during the last quarter of a century. The same situation applies to appendicitis. Endeavors to characterize different black populations in transition (including subjects who have had appendicitis) are being made respecting 1) diet, especially dietary fiber intake; 2) bowel physiology (e.g., transit time); 3) concentrations of fecal bile acids and other metabolites; and 4) the activity of certain fecal enzymes.

Is breast cancer avoidable? Could dietary changes help?

In the US, the life time odds of developing breast cancer has reached one in eight, with an incidence rate of 85 per 100,000 world population. The rate is half or less in women in some Mediterranean countries. At the extreme are rural African women whose rate is approximately 5-10 per 100,000. In African, compared with White women, protective factors include (1) reproductive behaviour, namely, slower growth before and after puberty, later age at menarche, high teenage pregnancy, high parity and long periods of lactation and amenorrhoea and (2) a diet of relatively low energy intake and of low-fat and high-fibre contents. In the Mediterranean setting, major dietary protective factors include a relatively low intake of saturated fat and high intakes of monounsaturated fat and of vegetables and fruit. Among White women, a reversion to protective reproductive behaviour is out of the question. Only in respect of diet, could significant avoiding action be taken. Adoption of an African type diet is wholly impracticable. Moreover, even conformation to a former Mediterranean diet, which is already changing, would be difficult, requiring reorientation of fat composition and large rises in intakes of vegetable and fruit. However, with resolution, were such changes made, at least by the very vulnerable, they would help, additionally, to protect against other diet-related cancers, especially colon cancer and against coronary heart disease.

An investigation of haemoglobin concentration and of blood loss in stools in adult South African bantu infested with intestinal Schistosoma mansoni

1. (1) An investigation has revealed there to be no significant difference in mean haemoglobin concentrations in medically fit Bantu mine workers with and without S. mansoni infestation (but with other helminths present indiscriminately in both groups). Mean values, also those of Bantu men and women farm labourers in indifferent health and dwelling where infestation of both forms of bilharzia is almost invariable, have been found to lie within normal limits for healthy white men and women, after correction for altitude. 2. (2) Observations demonstrate that such blood loss as occurs with S. mansoni infestation is irregular and small, thereby providing neither a handicap to haemopoiesis nor- an avenue of loss of nutrients or metabolites.

Prevalences of leg and chest abnormalities in four South African schoolchild populations with special reference to vitamin D status

Prevalences of bowing and knock knee, measured at a standard stance, have been obtained on Negro, Coloured, Indian and Caucasian schoolchildren aged 7, 12, and 16-17 years. These two abnormalities were unexpectedly common, affecting about one-fifth and one-third of all children respectively. Ranges of prevalences of chest abnormalities were—Harrisons sulcus, 0-5%, and pigeon chest, 0-2%. Prevalence of bowing increased with age. That of knock knee was little affected by age, but increased markedly with body mass. There was no age trend with prevalences of chest abnormalities. Prevalences appeared unrelated to vitamin D intake. As to sunshine, the annual mean for the Transvaal is 8·4 hr daily. Results from radiological, skin pigmentation, and biochemical studies were non-contributory. Since a primary deficiency of vitamin D is evidently not the causal factor, one explanation is that a secondary deficiency is involved, arising from an impairment in metabolic availability. Further, a proportion of leg abnormalities may be physiological variants; moreover, it cannot be excluded that unknown factors may bear, or share, in responsibility. Elucidation may be forthcoming by investigating the interrelationship between vitamin D status and frequency of leg abnormalities during and after puberty; in addition, results of serial studies of prevalences of abnormalities from birth to post-adolescence would be illuminating.