Many experts, particularly medical doctors, claim that dietary supplements of micronutrients are not necessary. It is often claimed by such experts that we ‘get all the vitamins in we need in foods and any additional nutrients simply give us expensive urine’. However, such proponents never explain what they mean by a balanced diet. As apparently healthy diets from around the World can be compositionally quite different, this ambiguous use of terminology is not helpful. Further, such proponents never differentiate between vitamins and minerals. This second point is pivotal because they are derived from quite different sources in quite different ways. Vitamins are organic molecules that are synthesised by plants. Diets rich in plant foods therefore tend to contain high amounts of vitamins. However, minerals are inorganic, and as such are not produced by the plants but instead originate in the soil. Even the highest quality diets can therefore be devoid of minerals if the crops eaten are from mineral poor soils.
Generally the evidence in the nutritional literature does not support the contention that modern agriculture and food manufacture and distribution can supply diets that contain adequate micronutrient contents. In particular, the low mineral status of much of the food supply has been evidenced. While processed foods are particularly poor in minerals, even high quality diets can be deficient and inadequate for human health. A number of well designed studies dating back many decades have shown that mineral supplementation can benefit the health of humans. Pregnancy is one time that mineral status is stressed particularly because the growing foetus has a requirements for essential minerals and these must be supplied from the maternal mineral stores. In this regard, dietary requirements increase and without adequate intake the foetus take priority on reserves, placing the mother at risk of deficiency diseases. The increasing risk of diabetes as pregnancy progresses may for example be partly due to diminishing chromium status.
The chromium status of pregnant women tends to decline as pregnancy proceeds. This has been reported in the nutritional literature. For example, in one study1, researchers measured the urinary chromium excretion during pregnancy and performed an oral glucose tolerance test at different stages of pregnancy, in healthy women. The results showed that as pregnancy proceeded, the mean chromium content of urine (expressed in relation to creatinine levels) decreased. Further, when the oral glucose tolerance tests were administered, mean chromium excretion decreased significantly. This latter finding was significant because following an oral glucose tolerance test the plasma levels of chromium usually rise, and this results in an increase in urinary excretion of chromium. The decreases in urinary chromium following an oral glucose tolerance test therefore indicates that chromium stores in the women were deficient. Further to this the authors concluded that the diets of the women were inadequate in terms of chromium intake, and recommended that supplementation would be beneficial.
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