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Could Broccoli and Soy Be Slowing Your Metabolism?

Many people believe that eating broccoli and soy is healthy, while others believe these foods can slow metabolism and negatively affect their thyroid function. Perhaps you heard or read this piece in Oprah magazine about how broccoli, soybeans, cauliflower, Brussels sprouts, and cabbage contain goitrogens, a substance that slows production of thyroid hormones. And now you may be wondering, "Are they healthy or harmful? Which is correct?"

There are many more factors that to consider before you cross out these veggies from your shopping list.

Your thyroid is a butterfly shaped gland that sits at the base of the neck, just above your collarbone. Although its size is pretty small, its function is not. The thyroid provides metabolic fuel for literally every cell in your body and plays a key role when it comes to losing fat. When you suffer from low thyroid (hypothyroidism), everything slows down. People with hypothyroidism can feel tired, bloated, and constipated. Their skin is dry, their hair falls out, and they can't shed fat.

According to the U.S. Department of Health and Human services, almost 5 percent of Americans age 12 and older suffer from hypothyroidism. While there are several causes for hypothyroidism, it is estimated that nearly 90% of these cases are due to Hasimoto's Disease, an autoimmune disorder causing a choronic inflammation of the thyroid (i.e. your immune system attacking your thyroid). Not broccoli and not soy.

Hypothyroidism and Nutrition

One of the most insidious bits of thyroid nutrition advice out there is that broccoli and soy can shut down your thyroid. It's not really accurate.

The reason Brassica veggies like broccoli and Brussels sprouts, as well as soybeans, canola and a few others, make the thyroid no-no list, is because they do contain compounds called goitrogens. And goitrogens disrupt the normal production of thyroid hormone by blocking the thyroid from taking in iodine - which is essential ingredient in making thyroid hormone.

The good news is, unless you suffer from a thyroid disorder, eating these veggies will more than likely not affect you. According to Dr. David Katz, if you "get adequate iodine in your diet--which most of us do courtesy of iodized salt--then goitrogens will have no noticeable effect." Additionally, Krause's  "Food, Nutrition & Diet Therapy," says that cooking and/or heating/steaming these veggies inactivates the goitrogens in them.

Those who have an impaired thyroid will be more vulnerable to the subtle effects of goitrogens, and they could tip you into hypothyroidism (underactive thyroid).

If you think you could have a thyroid disorder, I would encourage you to consult with your physician, who can give you a blood test to find out if you require treatment.


Dr Brooke Kalanick, ND, MS, LAc is a naturopathic doctor and graduate of Bastyr University – the leader in natural medicine education, research and the training of holistically minded primary care providers.  Dr Brooke specializes in PCOS and Hashimoto’s hypothyroidism helping these fat loss resistant women feel, look and be better.  Her knowledge of both conventional and alternative medicine helps her give patients back the control of their body, their hormones and their life. As a woman and mother who shares these struggles, she helps the women she works with live the adage: between perfect and giving up, there’s better.

Dr Brooke shares strategies with you for being better on FacebookTwitterGoogle+ and Pinterest.

>> Read more of Dr. Brooke Kalanick’s articles here! <<

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