A number of studies have looked at the effects of biochemical individuality and selenium metabolism. It has been shown for example that the rate of selenium metabolism to the trimethylselenonium ion (TMSe) varies amongst selenium deficient Bangladeshi women. This suggests that selenium metabolism, a process which in not fully understood, shows individual variation. The implications for this suggest that selenium intakes may depend on the individual biochemical variability shown by the individual, and this makes it difficult to know how much selenium to take in order to fulfill requirements. The recommendation would therefore be to supplement with a dose of selenium at the upper end of the intake range in order to ensure satisfaction of the metabolic need for the mineral. A number of roles for selenium have been identified and selenium deficiency may have serious negative outcomes for pregnancy, including an increased risk of cystic fibrosis, as identified by Dr Joel Wallach.
Polymorphisms refer to different variations of the same gene. Polymorphisms are what causes the biochemical differences exhibited by an individual, and a number of polymorphisms is selenoproteins have been identified. The genes that encode for the selenium containing proteins dimethylglycine dehydrogenase, selenoprotein P and glutathione peroxidase have been shown to exist and these polymorphisms may affect the metabolism of selenium, and the subsequent selenium status of the individual. For example, in one study researchers1 assessed the dimethylglycine dehydrogenase variant rs921943, and found that it was significantly associated with the selenium status of pregnant women at 12 week gestation as measured by toenail selenium concentrations. In selenium supplemented women, the response to supplements in terms of the increase seen in plasma glutathione peroxidase between weeks 12 to 35 of gestation was associated with the presence of the selenoprotein rs3877899 gene variant.
Dr Robert Barrington’s Comments: These results suggest that variation in the selenium metabolism pathways exist. They also suggest that selenium requirements for individuals vary considerably depending on the polymorphisms present. This is likely to be similar for all vitamins and minerals that are essential to human health. Such variation is an important part of nutrition and one that is often forgotten. The art and science of nutrition calls for intelligent nutritional strategies to ensure that each individual obtains their own requirements for each essential nutrient. This is the only way that true health can be obtained. Blanket, one size fits all recommendations, as suggested by government bureaucracies and their paid agents do not address this problem adequately despite the use of normal distribution curves within these guidelines. The problem is further confounded by the fact that food quality varies so much, making it difficult to ensure consistent mineral and vitamin intakes.
RdB
