Iodine Deficiency Common in Vegetarians and Vegans
People whose diets do not include regular consumption of animal products may become deficient in iodine, according to a study in Annals of Nutrition and Metabolism (2003;47:183–5). Lacto-ovovegetarians (people who do not eat meat, but do eat dairy products and eggs) and vegans (people who do not eat any animal products at all) are most prone to becoming iodine deficient.
Iodine is a trace mineral that is essential for the production of thyroid hormones, including thyroxine (T4) and tri-iodothyronine (T3). Symptoms of iodine deficiency include enlargement of the thyroid gland (goiter), mental fatigue, coordination problems and stunted growth in children. Deficiency of iodine is common in developing parts of the world but this new study suggests it may also be common in certain populations in Western nations.
In the study, researchers collected 24-hour urine samples from 31 lacto-ovovegetarians, 15 vegans, and 35 adults eating a diet that included animal products (omnivores) and measured the amount of iodine. Dietary habits were assessed by a food frequency questionnaire for each participant. The World Health Organization has determined that a 24-hour urine iodine concentration less than 100 mcg per liter represents deficiency, while less than 50 mcg per liter suggests severe deficiency.
The average 24-hour urinary iodine concentration in omnivores, lacto-ovovegetarians, and vegans was 216 mcg per liter, 172 mcg per liter, and 78 mcg per liter, respectively. More than 25% of the lacto-ovovegetarians and 80% of the vegans were iodine deficient compared with only 9% of omnivores. Severe iodine deficiency was found in 27% of the vegans, 10% of the lacto-ovovegetarians, and none of the omnivores. Evaluation of the lacto-ovovegetarian and vegan diets showed that they both were lacking in iodine-rich foods, but lacto-ovovegetarians had a higher intake of iodine due to intake of dairy products and eggs.
Plant foods are generally poor sources of iodine, with the exception of various types of seaweed. Although all lacto-ovovegetarians and vegans in this study used iodized sea salt, it did not provide enough iodine to prevent deficiency in many individuals. Some health conscious people avoid salt to reduce their risk of high blood pressure but this may not be advisable for those susceptible to iodine deficiency. Studies suggest salt is only problematic for a small number of people with high blood pressure and that it is safe for the general population to consume in moderate amounts. Supplemental iodine is readily available at local health food stores.
Good sources of iodine include iodized table salt, beef, fish (particularly cod and mackerel), poultry, dairy products, eggs, legumes, and soy.
Darin Ingels, ND, MT (ASCP), received his bachelor’s degree from Purdue University and his Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. Dr. Ingels is the author of The Natural Pharmacist: Lowering Cholesterol (Prima, 1999) and Natural Treatments for High Cholesterol (Prima, 2000). He currently is in private practice at New England Family Health Associates located in Southport, CT, where he specializes in environmental medicine and allergies. Dr. Ingels is a regular contributor to Healthnotes and Healthnotes Newswire.
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