Can Too Much Broccoli Affect Your Thyroid?

Cooked broccoli poses fewer risks for people with thyroid problems.
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If you're concerned about how diet influences your health, particularly if you have thyroid problems, your concerns are valid. Certain foods, including broccoli, can exert adverse effects on your thyroid. You're likely wondering whether to avoid broccoli altogether or eat it in moderation. Separating fact from fiction makes all the difference when it comes to your thyroid health.

Iodine Significance

    You tire easily, have trouble keeping weight off and feel depressed when your thyroid hormones sink below optimal level. Immune dysfunction and problems metabolizing iodine are two main contributors to thyroid failure. Iodine serves is the primary nutrient your thyroid needs to produce thyroxine and triiodothyronine, two key hormones. Low dietary iodine is generally not a problem in the U.S., where manufacturers iodize salt. Issues occur when certain foods interrupt iodine metabolism, which can result in or exacerbate thyroid issues.


    Broccoli belongs to a vegetable family called cruciferae, which also includes Brussels sprouts, cauliflower, cabbage and green, leafy vegetables. Cruciferous vegetables contain a family of compounds that can trigger thyroid inflammation, known as goiter. Veggies belonging to this family bear the name goitrogen for this reason. Goitrogenic foods put your thyroid at risk, primarily if you already have a thyroid problem. Broccoli contains glucosinolates, a group of substances that can interfere with your thyroid's ability to utilize iodine.

Risk Factor

    Your risk increases if you have low iodine, since excess broccoli consumption further reduces availability. When this happens, your thyroid hormone levels decline. Research suggests that this may explain why many children refuse to eat broccoli. Some individuals have a genetic predisposition to dislike broccoli and other goitrogens. This seems to serve a thyroid-protective effect, according to a research paper published in the September 2006 issue of the journal "Current Biology." Data suggest that individuals who have evolved to dislike glucosinolate-containing foods have a lower risk of thyroid problems, according to researchers.


    While broccoli and other brassica vegetables harbor a downside to those with thyroid problems, don't avoid them altogether, advises Mario Skugor, author of "The Cleveland Clinic Guide to Thyroid Disorders." Cruciferous vegetables contain healthful substances unique to this family, so the benefits far outweigh the risks. Moderate your intake instead, Skugor suggests. Talk to your health-care provider to determine the amount that is right for you.


    Avoid eating broccoli raw if you have a thyroid problem. Although uncooked broccoli retains the most nutrients, this is also when its anti-thyroid compounds are highly potent. Glucosinolates are heat sensitive and degrade when cooked. Cook your broccoli past al dente until it's soft. You lose some nutrients but also decrease the glucosinolate content, which is more important if you already have thyroid issues.

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