Goitrogenic Vegetables: To Eat or Not to Eat?

A lot of people have asked me why I am not afraid to eat a lot of cruciferous vegetables, which can have a goitrogenic effect on the thyroid gland, even though I have Hashimoto’s Thyroid Disease.  My answer?  Cruciferous vegetables won’t hurt my thyroid, they will help it. 

Liver Health and Thyroid Hormone Conversion

Cruciferous vegetables are chock-full of nutrients and vital for detoxing the liver, which plays a key role in the functioning of healthy thyroid hormones, particularly the conversion of the storage hormone T4 to the bioavailable hormone T3.  When this conversion doesn’t take place, the result is an increase in Reverse T3 which blocks Free T3 (the thyroid hormone that’s actively used in our cells) and the end effect is hypothyroid symptoms (fatigue, lack of motivation, depression, weight gain, hair loss, etc.).

This can be confusing to some doctors who are trained to by go TSH because TSH can be what they consider normal.  Even Free T3 levels can be normal, while Reverse T3 levels are building up, blocking all the Free T3 that is there.

Estrogen Metabolism Helps Thyroid Hormone Health

Cruciferous veggies are crucial for healthy estrogen metabolism (those of you taking DIM supplements know this!), which is important for both men and women and positively impacts thyroid hormone health.

Fermented Veggies Help Everything

Many of cruciferous vegetables make great ferments which are rich in healthy bacteria for our gutsA healthy gut helps protect thyroid function.  Fermented garlic sauerkraut in particular is loaded with probiotics, especially s. Boulardii, a good yeast strain; really, the benefits are infinite.

Crucifers are Anti-Inflammatory

Crucifers contain sulforaphane, which stimulates the release of antioxidant enzymes, i.e. crucifers are anti-inflammatory.

Crucifers are Anti-cancer

Crucifers reduce the risks of cancer, even thyroid cancer. (See links below.)

Want to Eat Crucifers?  Keep Iodine Levels Optimal

Unless you’re low in iodine, affects on your thyroid gland are likely not a concern.  The Paleo Mom explains the science behind cruciferous vegetables and iodine health:

“Importantly, the evidence linking human consumption of isothiocyanates or thiocyanates with thyroid pathologies in the absence of iodine deficiency is lacking. This means that these substances have only been shown to interfere with thyroid function in people who are also not consuming adequate amounts of iodine (if you are severely deficient in iodine or selenium, addressing those deficiencies before consuming large amounts of cruciferous vegetables is a good idea; see page ##). In fact, the consumption of cruciferous vegetables correlates with diverse health benefits, including reducing the risk of cancer (even thyroid cancer!). In a recent clinical trial evaluating the safety of isothiocyanatesisolated from broccoli sprouts, no adverse effects were reported (including no reported reductions in thyroid function).”  http://www.thepaleomom.com/2013/04/teaser-excerpt-from-the-paleo-approach-what-about-the-goitrogens-in-cruciferous-veggies.html

Frankly, we should be far more worried about the environmental toxins that are causing our thyroid issues (anti-thyroid and mood depressing fluoride in our tap water, for one) than about such nutrient-dense, anti-cancer, gut health-helping foods.

Dr. Mark Hyman also has a wonderful, clear article on goitrogens:

“There is a lot of chatter in the pop-nutrition culture saying that these vegetables have an ill effect on the thyroid because they contain goitrogens. . . .

The truth is, you would need to consume a large amount of these vegetables for their goitrogenic constituents to have an impact on your thyroid. Even more important is that you would have to consume them raw [emphasis mine]. When was the last time you ate 10 cups of raw Brussels sprouts or blended up 5 cups of raw kale in your Dr. Hyman’s Whole Foods Protein Smoothie and consumed it every day?

. . . So, my advice is not to worry about eating moderate servings of raw or cooked cruciferous veggies and to actually make a point of consuming 1 to 2 servings of them daily because they are so fundamentally crucial to disease prevention (especially cancer), as well as normal metabolic function (such as detoxification).”  http://drhyman.com/blog/2015/06/10/food-bites-with-dr-hyman-crucifers-and-thyroid/#close

If you do have concerns about consuming goitrogenic foods, cook them a little before consuming.  Just remember: the more you cook them, the more the nutrients are lost.

More good info on the health benefits of cruciferous vegetables:

References

  1. Higdon J, Delage B, Williams D, et al: Cruciferous vegetables and human cancer risk: epidemiologic evidence and mechanistic basis. Pharmacol Res 2007;55:224-236.
  2. Wu QJ, Yang Y, Vogtmann E, et al: Cruciferous vegetables intake and the risk of colorectal cancer: a meta-analysis of observational studies. Ann Oncol 2012.
  3. Liu X, Lv K: Cruciferous vegetables intake is inversely associated with risk of breast cancer: A meta-analysis. Breast 2012.
  4. Liu B, Mao Q, Lin Y, et al: The association of cruciferous vegetables intake and risk of bladder cancer: a meta-analysis. World J Urol 2012.
  5. Liu B, Mao Q, Cao M, et al: Cruciferous vegetables intake and risk of prostate cancer: a meta-analysis. Int J Urol 2012;19:134-141.
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  7. Bosetti C, Negri E, Kolonel L, et al: A pooled analysis of case-control studies of thyroid cancer. VII. Cruciferous and other vegetables (International). Cancer Causes Control 2002;13:765-775.
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  9. Higdon J, Drake VJ: Cruciferous Vegetables. In An Evidence-based Approach to Phytochemicals and Other Dietary Factors 2nd edition: Thieme; 2013
  10. Krajcovicova-Kudlackova M, Buckova K, Klimes I, et al: Iodine deficiency in vegetarians and vegans. Ann Nutr Metab 2003;47:183-185.
  11. Leung AM, Lamar A, He X, et al: Iodine status and thyroid function of Boston-area vegetarians and vegans. J Clin Endocrinol Metab 2011;96:E1303-1307.
  12. Office of Dietary Supplements, National Institutes of Health. Dietary Supplement Fact Sheet: Iodine.
  13. Tonstad S, Nathan E, Oda K, et al: Vegan diets and hypothyroidism. Nutrients 2013;5:4642-4652.
  14. McMillan M, Spinks EA, Fenwick GR: Preliminary observations on the effect of dietary brussels sprouts on thyroid function. Hum Toxicol 1986;5:15-19.
  15. Chu M, Seltzer TF: Myxedema coma induced by ingestion of raw bok choy. N Engl J Med 2010;362:1945-1946.
  16. Zhang X, Shu XO, Xiang YB, et al: Cruciferous vegetable consumption is associated with a reduced risk of total and cardiovascular disease mortality. Am J Clin Nutr 2011;94:240-246.
  17. Hooper LV: You AhR What You Eat: Linking Diet and Immunity. Cell 2011;147:489-491.
  18. Zimmermann, M.B. & Köhrle, J., The impact of iron and selenium deficiencies on iodine and thyroid metabolism: biochemistry and relevance to public health, Thyroid. 2002 Oct;12(10):867-78
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