Natural News - June 1999

Are Vegetarians Iodine-Deficient?

Vegetarians are ripe for iodine deficiency, according to a small study by Thomas Remer, Ph.D., of the Research Institute of Child Nutrition in Dortmund, Germany, where the soil is notoriously low in iodine.

More than 1 billion people worldwide have iodine deficiencies and are at risk for goiter, as well as growth, mental and psychomotor abnormalities. Iodized salt and products from animals fed iodine-enhanced diets have drastically reduced those problems in industrialized countries, yet such measures exclude most true vegetarians.

Remer studied three men ages 31-49 and three women ages 24-25 in a controlled experimental diet study. Subjects ate three different diets for five days each: a normal omnivorous diet, a high-protein omnivorous diet and a lactovegetarian diet that included vegetables and dairy products. None of the diets contained iodized salt or iodine-rich seafood.

When subjects' urine was analyzed 24 hours after meals, the iodine excreted exceeded the amount ingested in each instance. People on the lactovegetarian diet, however, demonstrated the greatest discrepancies. The amount of iodine they excreted was double what they got from their meals (40 mcg vs. 20 mcg). The adult RDA for iodine is 150 mcg. If maintained for even several months, such a diet is a sure risk for goiter problems or hypothyroidism. Vegans, who do not eat iodine-enriched dairy products, are at even higher risk.

A 1992 study found that 12 percent of North American vegetarians not using iodized salt had elevated thyroid-stimulating hormone levels, a sign of thyroid deficiency. And despite its origin, sea salt does not contain iodine—to get the RDA, vegetarians living in iodine-deficient areas should eat seaweed or iodized salt.

—British Journal of Nutrition 1999 Jan;81:45-9