HYPOTHYROIDISM & GOITROGENIC FOODS

Q. I have hypothyroidism that is pretty well managed by medication. I know there are certain foods that tend to exacerbate hypothyroid symptoms (goitrogens) but I have not been able to find much information about how much of these foods I can eat before they will have this effect. As many goitrogens are both foods I love and foods that are well-known to be good for me, I hesitate to give them up. Just how bad are these foods for my thyroid?

A. There are a variety of foods, unfortunately most being nutrient dense vegetables and fruits, that have goitrogenic properties. This means that they inhibit thyroid functioning. It is generally accepted that goitrogenic foods do this one of two ways, either by inducing antibodies that cross react with the thyroid gland directly, or by interfering with thyroid peroxidase (TPO). TPO is the enzyme that is responsible for adding iodine to thyroid hormone. Cruciferous vegetables, such as broccoli, brussel sprouts, cabbage, cauliflower and kale are among the more well-known goitrogens. Soy and soy products are also said to have significant goitrogen potential. Other foods, like millet, peaches, pears, spinach and strawberries, are said to also have a mild goitrogenic effect.

The gluten connection
Something else I would like to mention here is the research linking hypothyroid symptoms with gluten intolerance, or Celiac disease. A number of studies suggest that all individuals who test positive for anti-thyroid antibodies, should be tested for Celiac disease, as well. Some health professionals are finding that in cases where medication does not seem to be adequately controlling thyroid symptoms, Celiac disease is at the root. Avoidance of all gluten containing foods can reduce symptoms completely for some individuals. Gluten therefore, is a lesser known goitrogen that induces production of antibodies against the thyroid gland.

Can I have my cruciferous and thyroid hormone, too?
Not only are many of these foods delicious, there is no denying that they are also nutrient dense. That being said, individuals with hypothyroid conditions do not need to cut them out altogether. There are some simple solutions to decrease the goitrogenic potential in foods. In cruciferous vegetables, it is believed that isothiocyanates are the constituent responsible for the goitrogenic effects. They have been shown to block TPO and may also disrupt signalling across thyroid cell membranes. Heating alters the structure of these compounds. A light steaming can therefore help to decrease potential negative effect on thyroid function, while maintaining nutrient levels. Genisten, among other soy isoflavones found in soy products, is also thought to interfere with TPO. Another option for soy lovers is to enjoy fermented soy products instead. The fermentation process can drastically decrease the effect that soy products have on thyroid hormone production. Tempeh and miso are excellent sources of fermented soy.

How much is safe?
Sadly there are no hard and fast rules for 'how much' of these foods you can safely enjoy. For individuals who are currently taking desiccated or artificial thyroid and feeling well-controlled, this information should simply serve as a guideline. Goitrogenic foods can still be eaten, but should be done so in moderation. What this means exactly will vary from individual to individual, but I would not recommend eating these foods raw on a daily basis. For others that are choosing to go the more natural route, or just beginning thyroid therapy of any sort, you may want to avoid these foods altogether until symptoms are under control. I encourage you to pay close attention to your own symptoms. Keep a diet journal for the course of one to two weeks Keeping in mind that it can take up to 3 days for symptoms to manifest, do three days straight of these foods with every meal, then 3 days off of them entirely. Was there any difference in energy, bowel movements, temperature regulation, sleep, etc? If no difference was noticed, then perhaps your body tolerates these foods well and you can incorporate them in moderation, somewhere around 4-6 servings per week. Other individuals may notice a drastic improvement in symptoms after avoiding these foods for just a few days, and in that case, may want to be much more cautious, eating them as an occasional treat, as opposed to part of a typical diet.

Your best bet is to keep rotating through a large variety of vegetables, fruits and grains, including sources that have goitrogenic potential. Listen to what your body is telling you and remember MODERATION.

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