Effects of soy on hormones and thyroid function
How eating soy affects Hashimoto’s and immune health
In the past twenty years soy has become a popular food all around the globe. Although there are many health benefits of eating soy, there are side effects to be aware of.
A possible side effect of soy is that in some people it may affect thyroid function, especially in people with an underactive thyroid as it might interfere with the absorption of thyroid medication (1–4).
Our internal research at BOOST Thyroid found that 1 in 4 people have identified soy as a trigger of their autoimmune flare-ups.
Soy has more protein and fat, and less carbohydrates, than other legumes. The quality of soy protein is also much higher than other plant proteins (5–7). Soy’s low carbohydrate content can make it good food option for some diabetic patients (8).
Soybeans’ carbohydrates can help the growth of good colon bacteria, this is why soy carbohydrates are considered as prebiotics (9–11). The soybean is a good source of vitamins and minerals, including potassium, iron, and calcium, as well as omega-3 essential fatty acids (5, 6, 12–15). It also might be useful to know soybeans’ carbohydrates can increase flatulence (16).
Health benefits of soy (17–28):
- Protecting heart health
- Protecting against breast and prostate cancer
- Protecting bones
- Relieving menopausal symptoms
- Helping with diabetes
The impact of soy on thyroid and immune function
Consuming soybeans might inhibit thyroid function in some people by blocking iodide uptake and preventing zinc from functioning. Both zinc and iodide are important nutrients necessary for T3 and T4 production (29, 30).
Additionally, soy might interfere with the absorption of thyroid medication in some people (1–4).
Isoflavones are the main active component of soybeans that produces both hormonal and non-hormonal effects (31).
The chemical structure of isoflavones is similar to the hormone estrogen. Thus, they’re able to partially replace some of estrogen’s functions in various organs including the skin, spleen, pancreas, kidney, thymus, adrenal gland, brain, pituitary, ovaries, and testes (32–37). This could cause problems for some people-having high estrogen levels and then having isoflavones mimic estrogen could further increase inflammation and the risk of certain cancers.
Isoflavones in soy can be problematic for some people with an underactive thyroid and Hashimoto’s. They can block the function of the enzyme thyroid peroxidase (TPO), which is necessary for the thyroid to be able to produce T3 and T4 hormones (38–40).
There’s also clinical evidence that isoflavones can affect immune function (41). Some researchers have hypothesized that consumption of processed foods with high salt content could be a big factor in the triggering of autoimmune conditions (42–47).
A vegetarian diet is usually rich in foods containing soy, and can increase the risk of chance of developing an underactive thyroid (48).
Foods that contain soy:
- Vegan meat alternatives
- Soy-based sauces (shoyu, tamari, and teriyaki)
- Soy nuts
- Soy flour
If you are affected by soy intolerance, or if you’ve identified soy as a cause of your flare-ups, talk to your medical health care practitioner or nutritionist to find an alternative foods.
If you eat soy, remember to take your medication at least a few hours apart, as soy products can interfere with the uptake of thyroid hormones.
If you’re trying a soy-free diet, track it in BOOST Thyroid app to help you understand if your symptoms improve. In order to discover if soy is your trigger, try the diet for at least ten days to feel the first effects and don’t change your other dietary routines.
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Originally published on www.boostthyroid.com on May 24, 2019.