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Review Article - Insights in Nutrition and Metabolism (2018) Volume 2, Issue 2
Diet therapies: bad communications and useless application in healthy individuals.
Among human diseases based on defect in metabolism of food components, there are cases for which no drug therapy is applicable and dietary restriction constitutes the unique therapy. Accumulation of metabolites or not metabolized compounds determines troubles at different levels, so that a toxic effect is due to a molecule that is innocuous for healthy people. Removal from diet of food containing the “individually-toxic” molecule is the only therapy for such patients. However, it can introduce adverse effects. Therefore, it is damaging the trend to use such diets also when not prescribed by doctors. Among pathologies requiring a “(food-component)-free diet”, coeliac disease, galactosemias, phenylketonuria represent examples for which diet that excludes the dangerous food (or food component) is the main or the unique therapy, although drugs or alternatives begin to be in use or tested. Doctor’s prescription of such diets as therapy must be rigorously applied by patients, by considering the toxic effects due to accumulation of not correctly metabolized compounds. Galactosemia disease is a family of genetic defects affecting one of the three enzymes involved into the metabolism of galactose. The error in galactose metabolism determines accumulation of galactose, with toxic effects for the patient. This is an inborn gene defect, so that newborns cannot assume food containing galactose; this includes mainly milk, although this is their natural form of nutrition: however, to remove galactose, the correct contribution of calcium and vitamin D is compromised. Alternative food has been defined for galactosemic infants, because the galactose-free diet is considered the only therapy. Similarly, no phenylalanine can be assumed by people affected by phenylketonuria, an autosomal recessive inborn error of metabolism due to deficiency of phenylalanine hydroxylase that prevent the correct phenylalanine metabolism. Removal of food containing phenylalanine implies difficulties in rigorous following the diet, and more relevant, it implies the removal of food containing proteins, with consequent loss of protein uptake and the needs to introduce other amino acids in different way. One of the most known diet is the gluten-free diet, required for celiac disease patients. Also in this case, removal of food containing a given component is required for specific patients; however, this alters the correct contribution of other nutrients that may be not present in alternative food. This means that there is no advantage, and maybe disadvantages to apply some “(food-component)-free diet” without a pathological state and a clear prescription as therapy. In the following paragraphs we will discuss aspects related to some diet that requires the removal of specific food components.
Author(s): Deborah Giordano, Bernardina Scafuri, Angelo Facchiano