Fat-soluble vitamins in food supplements: do the labels follow the recommended doses?

Abstract

Introduction: Adequate vitamins consumption is indispensable for the maintenance of health and to prevent disease. Both poor and overdose intakes may result in adverse health effects [1]. Recommended Daily Allowance (RDA) is the average daily level intake sufficient to meet the nutrient requirements of nearly all (97-98%) healthy individuals [2]; Tolerable Upper Intake Level (UL) is the maximum level of total chronic daily intake of a nutrient judged to be unlikely to pose a risk of adverse health effects to humans [3]. Owing the ability of fat-soluble vitamins to accumulate in the liver and adipose tissue, they present a higher potential for toxic effects than water-soluble vitamins. The aim of this study was to evaluate if daily doses of fat-vitamins (vit) mentioned in food supplements (FS) labels are in conformity with the RDA defined by European Union Directive [4]. Materials and methods: A total of 165 FS sold in Portuguese pharmacies, supermarkets, health shops and on internet were examined for indicated daily intake and dosage of vitA, vitD, vitE and vitK. Selection criteria: oral solid pharmaceutical forms for adults, containing at least one fat-vitamin in its composition, as stated in the label, regardless of FS purpose. Results: 48% of the FS labels presented doses of one fat-vitamin > RDA and 23% FS with 2 or more vitamins > RDA. Only 30% of FS indicated all fat-vitamins doses ≤ RDA. It is noteworthy that some FS presented daily doses above UL defined by EFSA [3] (Table 1). Discussion and conclusions: Since fat-vitamins may be stored in the body and are slowly eliminated, the chronic intake of high doses should be monitored to prevent adverse effects of these vitamins (e.g. vitA: visual disorders, liver and kidney damage, birth defects; vitD: muscle and joint pain, cardiovascular and renal disorders; vitE: hemorrhage, higher risk of prostate cancer; vitK: coagulation disorders).This study revealed that the majority of FS labels recommended daily doses of fat-soluble vitamins above RDA, some even above UL. Therefore, it is crucial that doses of vitamins present in FS are reviewed ensuring the safety of these products.