Q. About six months ago, I started eating large amounts of raw cruciferous vegetables, unaware that this affects thyroid levels. Yesterday, I went for an annual physical with blood work, and the doctor said it looks like my thyroid is out of whack. I may be hypothyroid.
If I stop eating broccoli, cabbage and other raw crucifers, will this make the thyroid levels return to normal?
A. Research on this question is surprisingly scarce. Although some data suggest that soy may affect thyroid function, there is almost nothing about vegetables such as broccoli, Brussels sprouts or cabbage. They have traditionally been considered to cause goiter, but it is possible that they have negative effects on thyroid only when consumed raw (Human Toxicology, Jan. 1986) or when thyroid function is already under stress (Journal of Medicinal Food, Winter, 2003).
These vegetables are prized as part of a heart-healthy, anti-cancer diet. We suspect that if your vegetable consumption is responsible for changing your thyroid hormones, it should return to normal within a few months of reducing your crucifer intake. Please let us know the results of your “experiment.”
You can learn more about how to interpret thyroid panel results, as well as approaches to treating hypothyroidism, in our Guide to Thyroid Hormones.