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Women with iodine deficiencies are more likely to develop breast cancer. Eat more of these iodine-rich foods to reduce your risk.
The myth persists that a mammogram is the number one way to avoid breast cancer.
Real breast cancer prevention starts with attention to diet, exercise, stress reduction, and environmental toxins.
And when it comes to diet, one of the best nutrients to help ward off breast cancer is iodine.
If you think about it at all, you probably associate iodine with your thyroid. Too little of this element can lead to a painful swelling of the thyroid known as a goiter.
But iodine also plays a crucial role in women's breast health. In fact, a woman stores more iodine in her breasts than in her thyroid.[i]
It's nature's way of protecting babies. Iodine is critical for brain development in infants. Storing iodine in the breasts insures a good supply of this essential brain mineral in breast milk.
But when a woman's supply of iodine is low, it's not just a nursing baby who's at risk. Women with iodine deficiencies are more likely to develop breast cancer.
What's the link between low iodine and breast cancer?
When iodine levels are low, the ovaries produce more estrogen.[ii] Higher circulating levels of estrogen raise the risk of reproductive cancers like prostate, endometrial, ovarian, and breast cancers.
Dr. Bernard Eskin was a pioneer in iodine research. He discovered that iodine-deficient breast tissue is more likely to have pre-cancerous changes and that iodine could reverse those changes.
In lab studies he showed that iodine up-regulated 29 genes and down-regulated 14 genes in breast cancer cells, leading to cellular death[v] and suppression of tumor growth.[vi] Other animal studies show iodine can reduce breast tumor rates by 2.5 times.[vii]
And while iodine speeds the death of cancer cells, it leaves normal cells alone.
Epidemiological studies support the importance of iodine in breast health.
But the U.S. Dietary Reference Intake (DRI) for iodine is only 150 micrograms per day (or 290 mcg if you're pregnant or nursing).
By some estimates, Japanese women are getting about 25 times more iodine than the average American woman.[x]
Since the 1920s Americans have gotten most of their iodine from iodized salt. That's thanks to a government push to add iodine to salt to prevent goiter.
But in recent decades anti-salt propaganda has led to women cutting salt – and therefore iodine - from their diets. Since the 1970s rates of iodine deficiency have quadrupled.[xii]
Environmental toxins have also led to lower iodine levels. A group of chemicals known as halides binds to receptors inside your cells that are meant for iodine. They block the body's ability to absorb and use the iodine.[xiii]
These halides include perchlorate, a chemical used for rocket fuel. Perchlorate now contaminates our groundwater, soil, and food supply.
Chlorine and fluoride in drinking water also block iodine. So does bromine in flour, bread and baked goods.
If you're deficient you can still boost your levels and ward off many health dangers – including breast cancer.
But your body can't make iodine. You have to get it from food or supplements.
Good food sources of iodine are:
- Seafood (salmon, scallops, lobster, tuna, cod, and shrimp)
- Potato (unpeeled)
- Navy beans
But hands down the richest source of iodine comes from seaweed. It has 10 times or more iodine than other foods.
And it's powerful against breast cancer. A Japanese study found seaweed more potent than the chemo drug fluorouracil for breast cancer.[xiv]
Look for wakame, nori, arame, dulse, kombu, or kelp in Asian food markets and health food stores.
Add dried seaweed to the pot when cooking soups, grains, or beans.
And Maine Coast makes organic kelp granules that you can add to your (un-iodized) salt shaker or just sprinkle on your food before serving.
For more information visit Green Med Info's Health Guide on Breast Cancer.
[i]Patrick L, "Iodine: deficiency and therapeutic considerations." Altern Med Rev. 2008;13(2):116-27.
[ii] David Brownstein, MD "Iodine: Why You Need It, Why You Can't Live Without It" 2nd Edition, Medical Alternatives Press, Michigan, 2006.
[iv] Stadel BV "Dietary iodine and risk of breast, endometrial, and ovarian cancer." Lancet. 1976; 1(7965): 890-91.
[v] Frederick R. Stoddard II, Ari D. Brooks, Bernard A. Eskin, Gregg J. Johannes "Iodine Alters Gene Expression in the MCF7 Breast Cancer Cell Line: Evidence for an Anti-Estrogen Effect of Iodine." Int J Med Sci 2008; 5:189-196.
[vi] Shrivastava A, Tiwari M, Sinha RA, et al. "Molecular iodine induces caspase-independent apoptosis in human breast carcinoma cells involving the mitochondria-mediated pathway." J Biol Chem. 2006;281(28):19762-71.
[vii] Garcia-Solis P, Alfaro Y, Anguiano B, et al. "Inhibition of N-methyl-N-nitrosourea-induced mammary carcinogenesis by molecular iodine (I2) but not by iodide (I-) treatment Evidence that I2 prevents cancer promotion." Mol Cell Endocrinol. 2005;236(1-2):49-57.
[viii] Deapen D et al. "Rapidly rising breast cancer incidence rates among Asian-American women." Int J Cancer. 2002:10;99(5):747-50.
[ix] Yamagata N, Yamagata T. "Iodine content of thyroid glands of normal Japanese." J Radiat Res (Tokyo). 1972;13(2):81-90
[x] Aceves C, Anguiano B, Delgado G. "Is iodine a gatekeeper of the integrity of the mammary gland?" J Mammary Gland Biol Neoplasia. 2005;10(2):189-96.
[xi] Ziegler RG, Hoover RN, Pike MC, et al. "Migration patterns and breast cancer risk in Asian-American women." J Natl Cancer Inst. 1993;85(22):1819-27.
[xii]Hollowell JG et al. "Iodine nutrition in the United States. Trends and public health implications: iodine excretion data from National Health and Nutrition Examination Surveys I and III (1971-1974 and 1988-1994)" J Clin Endocrinol Metab. 1998;83(10):3401-8.
[xiii] Greer MA, Goodman G, Pleus RC, Greer SE. "Health effects assessment for environmental perchlorate contamination: the dose response for inhibition of thyroidal radioiodine uptake in humans." Environ Health Perspect. 2002;110(9):927-37.
[xiv]Hiroomi Funahashi et al. "Seaweed Prevents Breast Cancer?" Jpn. J. Cancer Res. 92, 483–487, May 2001