The Difference in Japanese Women
The typical diet of Japanese women includes lots of iodine-rich seaweed. It’s hypothesized that the higher iodine intake accounts for the decreased incidence of breast cancer in this demographic when compared with North American women.
Supporting this argument is the fact that when Japanese and other Southeast Asian women emigrate to Western countries and adopt the local diet, their incidence of breast cancer increases. (14)
In the early part of the twentieth century, food manufacturers started to add iodine to salt in an effort to add this important mineral to North American diets and prevent goiter. (15) We now know that too much salt (an easily-acquired taste) can raise blood pressure, with implications for cardiovascular illness and stroke risk.
Iodized salt is therefore not the best source for ensuring adequate iodine. The better option is to eat foods that naturally contain iodine; pregnant and lactating women should be especially vigilant to get enough. (16)
Iodine is found in trace amounts in many foods. If you eat a variety, you should be able to meet your daily requirement of sufficient iodine.
Recommended daily intake of iodine for adults and about twice that for pregnant and nursing women.
- Birth to 6 months: 110 mcg
- 7-12 months: 130 mcg
- 1-3 years: 90 mcg
- 4-8 years: 90 mcg
- 9-13 years: 120 mcg
- 14+ years: 150 mcg
Pregnant women: 220 mcg
Lactating women: 290mcg
Topping the list of iodine-rich foods is seaweed-you can add it to whatever you’re eating, raw or cooked. Others:
- cheese and other dairy
- saltwater fish and shellfish
- beans and legumes
- Himalayan salt
- unpeeled potatoes
What to Avoid
A class of chemicals called halides (of which iodine is one), found almost universally in the Western world, is known to interfere with hormone metabolism.
Other halides include fluorine, chlorine, and bromine. These chemicals all compete with iodine receptors in the body; over-exposure to other halides hinders the body’s absorption of iodine from the foods we eat.
Halides can be found in plastics, processed foods, soft drinks, fire retardants, medications, pesticides, fabrics, commercially baked foods, and swimming pools. Look for ingredients that contain “fluor-” (e.g., fluoridated water), “chlor-” (e.g., chlorine bleach), and “brom-” (e.g., brominated vegetable oil, potassium bromate) to keep these out of your diet.
If you are at risk for breast cancer (and for long-term breast health), you may benefit from adding a little more iodine to your diet. If you have a thyroid condition, consult your healthcare provider to discuss how to naturally regulate iodine levels.