La supplementazione umana con vitamina E = Vitamin E supplementation

After near to one century of research and speculations on beneficial properties, vitamin E has recently become to the scientific reconsideration due to possible adverse effects. Metanalysis studies have in fact suggested that supplementation at doses higher than 400 UI/die (i.e. 400 mg of synthetic alpha-tocopherol or approximately 180 mg of its natural form) would increase the risk of mortality in cardiovascular risk patients. Toxicology data provide solid evidence on the fact that vitamin E is well tolerated in humans. Toxicity effects are difficult to be demonstrated even at dosages of several grams per day maintained for years. The levels defined as potentially harmful in these metanalysis studies do not exceed the tolerable upper intake level (UL) nor the acceptable daily intake (ADI) that have been established by the most authoritative food safety and nutrition boards and institutions worldwide. For european countries these levels correspond to 300 mg/die and 0.15-2 mg/kg of body weight/die of natural alpha-tocopherol, respectively. These aspects and the debate on scientific value and implications for human health of the information rising from vitamin E metanalysis studies has lead to the conclusion that these do not provide a sufficient level of evidence for such a risk. On the other hand, these metanalysis studies have provided an occasion for further evaluating safety and need of dietary supplements that have been proposed for the primary and secondary prevention of chronic-degenerative diseases such as CVD, cancer and neurodegenerative diseases. Actually, largest clinical trials on vitamin E supplementation and assessed in these metanalysis studies did not provide solid evidence for any prevention effects. Therefore, massive and indiscriminate supplementation protocols should be avoided and the general population should be advised against this. A sceptic attitude has to be adopted against the use of high doses vitamin E as a therapeutic measure for the clinical end-points so far taken into consideration. Instead of this, it has to be recommended to reach the optimal intake of this vitamin (in Europe the RDA is 10 mg) by means of a balanced consumption of natural sources of this vitamin (main food sources of vitamin E are wheat germ, nuts and seeds, and plant oils in general), and this type of recommendation can guaranty to have all the possible beneficial effects of this vitamin as well as of other micronutrients, without any potential risk.