By cleaning up your diet to get rid of all the nasty stuff—persistent organic pollutants (POPs), saturated fats, additives and food colorings—you may be cutting out the iodine that you need. That doesn’t mean you should go back to eating unhealthy foods, but you need to make sure you have good sources of iodine, since we can’t take iodine sufficiency for granted anymore.
In the 1970s, the common belief was that iodine deficiency had been eradicated. But the most recent national nutrition survey found that more than one in 10 Americans are not getting enough of it. Deficiency among women is twice what it is among men, affecting 23 percent of women in their 40s and 15 percent of women of childbearing age.
"The group we are most concerned about is pregnant women, who need more iodine anyway," says Dr. Robert Utiger, professor of medicine at Harvard Medical School. "There is the possibility of irreversible damage to the fetus if the mother is deficient." Utiger adds that "even a low level of iodine deficiency might cause some impairment in intellectual development in fetuses or infants."
Are You At Risk?
You could be at risk for iodine deficiency if your diet fits into any of the following categories: Low-on-the-food-chain vegetarian or vegan diets; Diets without any ocean fish or seaweed; Low-sodium diets (including the use of non-iodized salt); Dairy-free diets or those low in dairy products.
Why the Decrease?
Iodized salt was introduced in the 1920s to combat iodine deficiency. Now, about half of the table salt sold in the U.S. is iodized. Farmers also began supplementing their cows" diets with iodine at that time. Even bigger increases in iodine intake came in the 1960s, when iodinated additives, sterilizing agents and food colorings began to be used in industrial bread, milk and cereal production.
By the 1970s, the widespread use of these unregulated industrial sources of iodine led to some people getting too much, explains Dr. John Dunn, professor of medicine at the University of Virginia and secretary of the International Council for the Control of Iodine Deficiency Disorders (ICCIDD). Use and consumption of those additives, sterilizers and colorings has declined, and the corresponding overall decline in iodine intake is actually good news, says Dunn.
Dunn cautions, however, that this is one case in which just trying to eat more healthy foods is not necessarily enough. A diet featuring all the best, freshest fruits and vegetables in the world won’t give you a radiant glow unless you are also getting sufficient iodine, which is found in high levels in only a few foods.
What Does Iodine Do?
Iodine is the backbone of all nutrients because the cells in the body need it to regulate their metabolism. Besides causing unsightly goiters, iodine deficiency slows all the systems of the body: The digestive system becomes sluggish, nails grow more slowly, skin and hair become dry and dull, tendon reflexes stiffen, sensitivity to cold increases, and the pulse slows. Iodine helps form who we are to such an extent that a deficiency can lead to a dulling of the personality, deterioration of attention and memory, increase in irritability due to fatigue and extreme apathy.
In children and adults, iodine deficiency can slow the ability to process information. This makes it a key nutrient for the information age. And, as Utiger stresses, in the case of developing fetuses and infants, iodine deficiency can cause intellectual retardation and permanent neurological and developmental damage. In fact, according to the ICCIDD, iodine deficiency is the single biggest cause of preventable mental retardation and brain damage in the world.
How Can I Get Enough?
There are some foods and supplements that can be counted on to give you enough iodine: Ocean fish including cod, haddock, sole and ocean perch (Atlantic redfish); Sea vegetables and seaweeds; Iodized salt; Many vitamin and mineral supplements.
Ocean Fish—An Environmental Quandary
While many types of ocean fish are good sources of iodine, they can also contain varying levels of PCBs, other POPs and elemental toxins, such as mercury. Cod, sole, haddock and ocean perch are decent choices because they are high in iodine but relatively low in mercury. Due to the mercury levels in these fish, the Food and Drug Administration recommends a maximum of 12 ounces per week while pregnant. That amount would still give enough iodine. Minimizing toxins isn’t the only environmental concern, though. The ocean species with optimum mercury/iodine balances are also those whose stocks have collapsed or are in peril due to overfishing.
Seaweed and Sea Vegetables
The good news for people trying to eat low on the food chain is that the world’s best source for iodine is actually a plant food—seaweed. Seaweed is such a good source that the only worry is getting too much iodine from it. The body can handle the occasional high dose, says Dunn, but habitually taking too much could block the body’s ability to metabolize iodine. The recommended maximum is 1,000 micrograms (mcg) per day.
Dr. Stephen Walsh, a member of the Vegan Society’s Council of Trustees in Great Britain, offers the following guidelines: Several sheets of nori seaweed could be eaten every day without any problems. By contrast, "because they are both so high in iodine, a half ounce of kombu or three and a half ounces of hijiki should last you about a year."
A quarter teaspoon of iodized salt provides about 90 mcg of iodine. Non-iodized sea salt is not a good source, and neither is so-called "living sea salt," because the iodine evaporates so rapidly.
Vitamin and Mineral Supplements
If you think it might be a while before you start garnishing your food with seaweed or extra salt, supplements may be the answer. A vegan diet generally provides about 50 to 80 iodine mcg/day, and a vegetarian diet provides 100 to 150 mcg/day, according to recent nutritional studies. For comparison, the Dietary Reference Intakes (DRIs) for iodine are: 150 mcg/day for men and women, 220 mcg/day for pregnant women and 290 mcg/day for breastfeeding women. "Don’t worry if your intake fluctuates from day to day," assures Dunn, who helped set the new DRIs. "It takes months of too little iodine to produce iodine deficien-cy." Adults can recover from deficiency, but studies have found it can take at least several months to correct its effects. The best course of action is to prevent the deficiency from developing in the first place.
ELEANOR ALLEN is a freelance writer living in Ottawa, Canada.