The efficacy and safety of nutritional supplement use in a representative sample of adults in the North/South Ireland Food Consumption Survey

Department of Food Science, Food Technology and Nutrition, University College, Cork, Republic of Ireland.
Public Health Nutrition (Impact Factor: 2.48). 10/2001; 4(5A):1089-97. DOI: 10.1079/PHN2001190
Source: PubMed

ABSTRACT To describe the current use of nutritional supplements and their contribution to micronutrient intakes in a representative sample of Irish adults, to evaluate the impact of supplement use on the adequacy of micronutrient intakes and to assess the risk to supplement users of exceeding tolerable upper intake levels (UL).
Food intake data were collected in 1379 (662 male and 717 female) randomly selected Irish adults aged 18 to 64 years using a 7-day food diary. The current use of nutritional supplements was assessed using a self-administered questionnaire and respondents entered each supplement as it was consumed into the food diary.
Twenty-three per cent of respondents regularly used nutritional supplements. Twice as many women used supplements as men. The intakes of micronutrients were significantly higher (P<0.001) in supplement users than in non-users. Micronutrient intakes from food sources were similar in male users and non-users of supplements, but were significantly higher (P<0.01) in female users, by 3 to 13%, for Fe, Mg, Mn, vitamins C and E and niacin than in non-users. The percentage of female users between 18 and 50 years who had mean Fe intakes below the average requirement (AR) (10 mg) decreased from 50 to 25 when the contribution from supplements was included. The use of supplements reduced the percentage of men who had mean intakes below the AR for Zn from 19 to 13, for riboflavin from 14 to 6 and for vitamin A from 20 to 5, and reduced the percentage of women with intakes below the AR for Ca from 23 to 16 and for riboflavin from 23 to 14. Twenty-one women out of 80 aged between 18 and 50 years, who consumed supplemental folate, achieved the intake of 600 microg recommended to prevent neural tube defects. Twenty-two per cent of the women who took iron and 15% of the women who took vitamin B6 in supplemental form had mean daily intakes that exceeded that UL for these nutrients. Supplement users did not exceed the UL for the other micronutrients.
Supplementation appears to be beneficial in promoting adequate intakes of some micronutrients, particularly Fe and folate in women aged 18-50 years and vitamin A in men. There appears to be little risk to supplement users of experiencing adverse side effects due to excessive intakes of micronutrients.

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    • "This indicates a very low risk of adverse effects from excessive intakes of micronutrients in the population. A small proportion (0·1 –2·2 %) of FF consumers had MDI of folic acid, vitamin B 6 , retinol, Ca, Zn, and vitamin E that exceeded the UL but this was mainly associated with the use of nutritional supplements (Kiely et al. 2001) or, in the case of retinol, of high liver consumption and was not affected by fortification, which contributed only small amounts to the intakes of these micronutrients relative to their UL. For example, 1·2 % of FF consumers (mainly women) exceeded the UL for vitamin B 6 (25 mg) with average daily intakes ranging from 30 –62 mg, mainly from supplements , while one FF consumer (male) exceeded the UL for Ca (2500 mg "
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    • "The present study aimed to assess the Zn status of healthy late middle-aged and older Europeans and to investigate the effects of Zn supplementation on their cognitive functioning. Note that even if the sample were not Zn deficient, there may be advantages in consuming some nutrients at levels beyond average requirements (Kiely et al. 2001). Moreover, we need to establish that supra-nutritional doses of Zn have no adverse effects. "
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    • "Women were excluded if they were taking medicines likely to affect vitamin D status or calcium metabolism (such as active vitamin D metabolites, parathyroid hormone (PTH), anticonvulsants, steroid hormones ). Four of the women were taking very high levels of supplemental vitamin D (56–63 mg/day), which is nonreflective of levels in vitamin D-containing supplements used by women aged 50 y and older in the general Irish population (Kiely et al, 2001), as well as being higher than the tolerable upper intake level (50 mg/day; Institute of Medicine, 1997). Therefore, these women were excluded from further analysis. "
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