NUTRITION AND HEALTH
|
The Independent Science Panel (ISP) is a panel of scientists from many disciplines, committed to the Promotion of Science for the Public Good. Read our statement here |
|
|
David Hywel Davies - 15th July 2005 The impact of nutrition on human health requires no emphasis. General awareness of their simple relationship has been created largely by the preoccupation of the medical profession over the last half-century with cholesterol and the attempts by official and other bodies to change our eating habits. The low-fat, low-cholesterol diet has been endorsed by the National Cholesterol Education Program in the US and similar public statements elsewhere in the world, and is still being pushed despite the many sceptics and the fact that no important relationship has been shown between people's consumption of cholesterol and their blood levels. There are many who believe that the net result of this, other than the vast profits that have accrued to food manufacturers and pharmaceutical companies, has been to increase the consumption of carbohydrates, resulting in diabetes and obesity. In other words, that the much-vaunted food pyramid has been upside-down all along. It is my opinion that there are other and more significant issues to be considered in the interplay between nutrition and human health, and in the time available I will concentrate on just a few aspects of infant feeding as typifying these, especially the provision of calories, calcium, phosphorus and Vitamin D. First , overfeeding in infancy can set the pattern not only for later obesity but also for important and permanent elevations in coronary �risk factors', such as blood cholesterol and insulin levels. which have been well-documented statistically. The physiological basis for this was provided by the animal experiments of Hahn [1] and Widdowson and McCance [2,3] some decades ago. The higher cholesterol and insulin levels persisted into adulthood, along with greater body weight, on a normal diet. Second , we must hark back to the World War II and the years following it when it was considered advisable to supplement the Btitish diet with considerable amounts of calcium and Vitamin D. Infants in Belfast consumed an average of as much as 1500 International units of Vitamin D a day [4] . The consequence was the appearance of what was labelled an �epidemic' of calcium and Vitamin D poisoning known as infantile hypercalcaemia, with its accompanying mental impairment and cardiovascular abnormalities. When this error of public health was appreciated and the supplementation much reduced, the cases ceased to appear. Now it appears that there are loud voices in the US clamouring for similar policies, and therefore mistakes, to be repeated there [5] . Third , an important pointer to the ill-effects of over-supplementation of the food-supply with Vitamin D has existed in the literature since 1972 and has remained unexplained. Meyer and Lind, the former from Germany and the latter from Sweden, studied the arteries of small children, half of whom had died suddenly in accidents, the other half from natural causes [6,7] . The former at least can be looked on as representing the �normal' population. Visible deposits of calcium phosphate (usually consisting mostly of apatite) were found in the carotid arteries to the head in all cases, and in the iliac arteries to the legs in half of the newborns. These findings are grossly abnormal and speak for some calcifying factors, environmental in origin and operating during pregnancy and/or infancy. Fourth , it is commonly accepted, and rightly, that human milk is ideal nourishment for the human baby. What is not widely appreciated is that cow's milk is much richer in calcium and phosphorus than is human milk, as the following table shows.
(The first five products are from the UK, the last two from the US). The mechanisms of calcification in living tissues are complex, but depend inter alia on what many of us will remember from our schooldays as the solubility product of calcium and phosphate ions. Heavy provision of the two elements, calcium and phosphorus, in the diet tends to raise their tissue levels, and hence the influx of calcium, given the right circumstances, to the interior of the body's billions of cells, a process that can be highly damaging to the cells and lead ultimately to cell-death. Given the wide range of human sensitivities to such agents as Vitamin D, one of whose prime functions is to encourage the absorption of calcium from the food, this will evidently be of more importance to some than to others. The problem of applying the same rules to all � a universal one beyond the limited confines of the present subject � is that we do not yet know which individuals these might be. The defining of the human genome has led to heightened awareness of the individuality of response to all exogenous factors, including drugs, natural products, and substances that have hormonal properties. This effectively ushers in the age of individualized medicine and sounds the tocsin for the practice of epidemiology as we have known it and have been misled by it. Fifth , the importance of calcium in all cellular activities, including cell division, multiplication, migration and secretion has to be realised. Its level within the cell is normally kept within strict limits and at a much lower level (up to even 10000 times) than that which obtains outside the cell. The difference in concentration is maintained by the blocking functions of the cell-membrane, the complex envelope which surrounds each cell, and any interference with the functions and integrity of this membrane will lead to elevated intracellular levels of calcium. Such interference can arise from a whole variety of environmental toxins. Sixth , it has been appreciated in recent years that the deposition of calcium salts where they do not normally belong is not an end-stage degenerative process but one which has great relevance to the beginning of disease processes, including those of the coronary arteries of the heart whose blockage causes angina and heart attacks [8] . Computerized scanning of the coronaries for calcium is now used clinically as an excellent marker of the presence or absence of disease. Seventh , the role of phosphorus is critical, and its consumption is often excessive � it averages 1500 mg a day in the US as against a need for 500, and again the element enters the human food chain from many directions, including soft-drinks, preservatives in food, agricultural practices etc.. Small increases in blood phosphorus levels can lead to a marked increase in the tendency towards tissue calcification when conditions are appropriate to this, especially when kidney function is impaired [9] . Eighth , Vitamin D is routinely used in the animal laboratory as a necessary prerequisite to create coronary disease. The doses used are usually large, but not always. It too finds its way into the human food chain in various ways, including the mandatory and ill-controlled supplementation of milk in the US. Since it encourages growth, Vitamin D is added to animal fodder along with antibiotics and steroids. There have been moves recently to give huge doses of Vitamin D and calcium to cattle a few days before slaughter in order to increase the tenderness of the meat [10] . If this practice became established it would inevitably lead to a further increase in human consumption. The average blood level of Vitamin D in the US [11] is already several times higher than is necessary for good health. In nature, a rapidly fatal disease of grazing animals, with widespread calcification of tissues, exists in many countries due to the consumption of plants rich in Vitamin D. In Argentina this is known as Enteque Seco and is due to a member of the potato family, Solanum malacoxylon [12] . In Europe it is called Enzöotic calcinosis and its cause is the consumption of yellow or golden oat-grass, Trisetum flavescens , a common inhabitant of our pastures. The reason given for widespread fortification of human foodstuffs with Vitamin D is to prevent rickets, an interference which is manifestly absurd in sun-drenched areas like California and Arizona. That there are many real concerns worldwide about undernourishment is evident, but these are regional and affected not only by local and general climatic conditions but by political considerations. The larger global problem now is, I believe, more likely to be in the domain of over-provision. Increasing Vitamin D provision is but one aspect of the tinkering with health which is encouraged by such as pathologists, biochemists and others who are relatively remote from clinical realities, and it is dangerous. It is unfortunate that the dialogue between nutritionists and the medical profession are notable by their absence, and that the declared function of the former is to provide adequate nourishment (for what exactly is rarely stated: the requirements for resisting infection are not the same as those for longevity or for other goals). This objective is without much concern for the clinical effects of excess, and it is time that more attention was paid to maximal rather than minimal requirements. The result is that a bit of this and a bit of that finds its way into, for instance, infant formula, each perhaps a good idea in itself. Nestlé in their brochure state that they employ 300 research scientists and have got themselves into the dubious business of mixing food and drugs, which they call phood. The end result likewise, in my opinion, will have little to do with the needs of promoting health through nutrition. I chose at random from the shelf of a US supermarket a can of baby formula, viz. ' Enfamil with Iron, Milk-based Infant Formula for Baby's First 12 Months '. Under 'Ingredients' I found the following: Reduced mineral whey, non-fat milk, lactose, palm olein oil, soy oil, coconut oil, high oleic sunflower oil, and less than 1% mono- and diglycerides, soy lecithin, carrageenan, vitamin A palmitate, vitamin D3, vitamin E acetate, vitamin K1, thiamine hydrochloride, vitamin B6 hydrochloride, vitamin B 12, niacinamide, folic acid, calcium pantothenate, biotin, sodium ascorbate, ascorbic acid, inositol, calcium chloride, calcium phosphate, ferrous sulfate, zinc sulfate, manganese sulphate, cupric sulphate, sodium chloride, sodium citrate, potassium citrate, potassium hydroxide, sodium selenite, taurine, nucleotides (adenosine 5'-monophosphate, cytidine 5'-monophosphate, disodium guanosine 5'-monophosphate, disodium uridine 5'- monophosphate). No comment seems necessary, except to say that I could not help wondering what my grandmothers who between them brought up sixteen healthy children without the benefit of carrageenan, soy, calcium, disodium guanosine 5 ' -monophosphate and the rest would have said about this. Nor Pericles, for that matter, who believed in the virtues of simplicity. References
|
| e-mail:[email protected] |
© 2003 Independent Science Panel