Are ovo-lacto-pesco-vegetarians and vegans risk groups for suboptimal iodine intake? Iodine intake and status in a group of Norwegian vegetarians

Abstract

BACKGROUND: Iodine is a trace mineral of vital importance for brain development and function. Vegetarians generally avoid or limit their consumption of animal foods. Salt iodization in Norway is exceptionally low, and approximately 80% of dietary iodine derives from animal foods, with milk, seafood and eggs as the main sources. The iodine status in Norwegian vegetarians is unknown. OBJECTIVE: The main objective was to evaluate iodine intake and status of a group of Norwegian vegetarians. METHOD: Two day food diaries and morning spot urine samples for analysis of iodine concentration (UIC) were obtained from 52 vegetarians (including 18 vegans and 34 ovo-lactopesco-( OLP-) vegetarians) and 67 non-vegetarians (control group). Use of iodine containing supplements was reported, and evaluated in addition to the contribution of iodine from food. RESULTS: None of the vegans and 24% of OLP-vegetarians reached the recommended iodine intake of 150 μg/day with diet as the only source of iodine. Use of iodine-containing supplements was reported by 18% and 28% of OLP-vegetarians and vegans, respectively. When including iodine from supplements, 17% of vegans and 38% of OLPvegetarians reached the recommended intake of 150 μg/day. According to WHOs criteria for evaluating iodine status based on spot urine samples only 12% of vegans and 21% of OLPvegetarians had adequate iodine intake. In the total vegetarian group, the median urinary iodine concentration was 52 μg/L in noniodine- supplement and 102 μg/L in supplement users. High UIC (>700 μg/L) was found in three vegetarians using kelp supplements. Total iodine intake (food and supplements) did not differ between vegetarians and controls. CONCLUSION: This study showed that suboptimal iodine intake was prevalent in vegans, OLP-vegetarians and non-vegetarians. Although the participants are not representative groups of all vegetarians in the Norwegian population, the results highlight the need to focus on iodine nutrition in subgroups of the population