PMID: 14557795
Issn Print: 1363-1950
Publication Date: 2003/11/01
The question of micronutrient supplements
Excerpt
The emerging scientific evidence on the role micronutrients may or may not contribute to the prevention and treatment of disease, despite its apparent contradictions and confusion, as well as the attainment of so-called ‘optimal’ health attests to the extensive efforts being made to afford a better perspective on the reputed relationship. The impetus is further augmented by the often phenomenal projections on disease prevention (14 million cases of preventable heart disease, 1.2 million of cancer, more than half a million strokes, and 2500 children with preventable neural tube defects [1] in the USA alone), and the attendant potential, and equally phenomenal, savings in the healthcare budget (US$89 billion from delaying the onset of heart disease, stroke and osteoporosis by 5 years [2]), as well as an overall improvement in the quality of life. These concepts have undoubtedly arisen from the realization that micronutrient requirements for the prevention of disease may indeed differ from those used for the prevention of deficiency, in view of the inverse associations between a higher intake of some micronutrients, from food, and the prevalence of chronic disease [3]. The requirement for evidence-based nutrition has highlighted the urgent need for the development of appropriate and sensitive biomarkers regarding the definition of ‘optimal’ micronutrient nutriture, and for the documentation of favourable clinical outcomes from intervention trials. It can be successfully argued that it is the discordance between these two requirements, which at present intrigues the scientific community, and confuses the public from apparently contradictory findings. The spectrum of the current era in the scientific literature ranges from statements such as: ‘daily doses of multivitamin tablets: regular consumption will probably do you no good, with a few exceptions' [4], to ‘some people need a vitamin-mineral supplement to meet specific nutrient needs’ [5] to supplements being worthless or even potentially harmful [6,7]. The ongoing debate has also brought to the fore a number of questions of crucial importance. To exemplify ‘can one talk about micronutrient supplements in general terms for all people?’, ‘can one nutrient (the famous magic bullet), with defined functions, at least as best as we currently understand them, really have, on its own, a meaningful role in altering the course of disease in all people?’, ‘is it realistic to take a nutrient out of our complex food, administer it at higher doses and expect it to alter a given clinical outcome?’ or, for that matter, ‘are randomised, double blind, placebo controlled trials, the current gold standard, the appropriate methodology to employ in nutrition intervention studies of single nutrients?’. Irrespective of future developments, there is considerable scientific evidence in the recent literature to indicate that micronutrient supplements have decidedly beneficial effects in defined populations, defined settings and for defined and ‘rational’ outcomes.
The appropriate belief that micronutrients play an important role in health together with the inappropriate belief that ‘more is better’ has led to the liberal use of micronutrient supplements among adults and children alike. In the United States, for example, one out of four children younger than one year and one out of two children aged 2-11 years are given such supplements [8]. Similar patterns of consumption have been reported from other parts of the developed world [9]. Whereas the need for such supplements by children of the developed world has been questioned [10] when an ‘adequate’ diet is consumed, their importance in the correct setting(s) forms the basis of a number of nutrition intervention programmes in the developing world [11].
The importance of zinc in human nutrition, and the nutrition of children in particular, has been rather neglected until recently [12].
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