The European Food Safety Authority (EFSA) has published scientific opinions on dietary reference values (DRVs) for zinc, selenium, and chromium. They are part of EFSA's ongoing review of existing advice on DRVs for energy, macronutrients, and micronutrients.
Zinc: EFSA's Panel on Dietetic Products, Nutrition and Allergies (NDA) derived DRVs for zinc using a two-stage factorial approach and reference values for body weight. Estimated Average Requirements (ARs) and Population Reference Intakes (PRIs) are provided for phytate intake levels of 300, 600, 900, and 1,200 mg/day, which cover the range of mean/median intakes observed in European populations. ARs range from 6.2 to 10.2 mg/day for women with a reference weight of 58.5 kg and from 7.5 to 12.7 mg/day for men with a reference weight of 68.1 kg. PRIs were derived from the zinc requirement of individuals with a body weight at the 97.5th percentile for reference weights for men and women and range from 7.5 to 12.7 mg/day for women and from 9.4 to 16.3 mg/day for men.
ARs for infants from seven months of age and for children were estimated factorially, based on extrapolation from estimates of adult losses plus zinc needs for growth, and range from 2.4 to 11.8 mg/day. PRIs for infants and children were derived by assuming a coefficient of variation of 10%, and range from 2.9 to 14.2 mg/day. For pregnancy and lactation, additional zinc requirements related to fetal and maternal tissues and transfer of zinc into breast milk, respectively, were considered, and additional PRIs of 1.6 and 2.9 mg/day, respectively, were estimated.
Selenium: The leveling off of plasma selenoprotein P (SEPP1) concentration was considered indicative of an adequate supply of selenium to all tissues and to reflect saturation of the functional selenium body pool, ensuring that selenium requirement is met. This criterion was used for establishing DRVs for selenium in adults. However, EFSA encountered uncertainties in the data when examining human studies for the relationship between selenium intake and plasma SEPP1 concentration. Therefore, the data were considered insufficient to derive an AR.
An Adequate Intake (AI) of 70 µg/day for adults was set. No specific indicators of selenium requirements were available for infants, children, or adolescents. For infants ages 7–11 months, an AI of 15 µg/day was derived by extrapolating upwards from the estimated selenium intake with breast milk of younger exclusively breast-fed infants, taking into account differences in reference body weights. For children and adolescents, the AIs for selenium were extrapolated from the AI for adults by isometric scaling and application of a growth factor. AIs range from 15 µg/day for children ages one to three to 70 µg/day for adolescents ages 15–17. For lactating women, an additional selenium intake of 15 µg/day was estimated to cover the amount of selenium secreted in breast milk, and an AI of 85 µg/day was set.
Chromium: Trivalent chromium (Cr(III)) has been postulated to be necessary for the efficacy of insulin in regulating the metabolism of carbohydrates, lipids, and proteins. However, the mechanism(s) for these roles and the essential function of Cr(III) in metabolism have not been substantiated. The Panel concludes that no AR and no PRI for chromium can be defined. The Panel considered that there is no evidence of beneficial effects associated with chromium intake in healthy subjects. The Panel concluded that the setting of an AI for chromium is also not appropriate.