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.

Table 1. Results of FS with fat-soluble vitamins.

Vitamin	A	D	E	K
N	73	142	95	32
RDA	800 µg	5 µg	12 mg	75 µg
N > RDA (%)	22 (30)	90 (63)	54 (57)	10 (31)
UL	3000 µg	100 µg	300 mg	n.d.
N > UL (%)	3 (4)	11 (8)	2 (2)	–

Acknowledgements

The authors are grateful for the financial support provided for this study by Egas Moniz, CRL.