There are certain ‘healthy’ foods that are not that healthy if it comes to hypothyroidism. Or if you don’t know how to counteract their negative effect, you may be slowly damaging your thyroid. Let’s start with the most common and most controversial one at the same time – soy! Honestly, I haven’t seen any other food with so many different opinions as I’ve heard about soy. If it comes to hypothyroidism diet this is the top one that you should be really careful with.
So what’s wrong with one of the most popular protein sources for vegan and vegetarians? What we know for sure is that most of soy is genetically modified. We also know that soy is a strong goitrogen and can interfere with iodine absorption. Iodine together with tyrosine are two main building blocks for thyroid hormones. Without enough iodine you are not able to make thyroid hormones! Moreover, a lot of soy-based products are highly processed including ingredients and by-products you don’t want to consume. In terms of soy effect on thyroid, there is no doubt that you should be avoiding it.
Is fermented soy less goitrogenic?
Fermented soy is still goitrogenic but contains less other anti-nutrients like phytic and oxalic acid. It’s better digested too compared to raw soy. So why some people say soy is healthy?
Does soy have antioestrogen and anticancer properties?
The controversy starts around soy and cancer risk. Soy contains phytoestrogens that can bind to oestrogen receptors. What does it mean? It means that it can block action of real oestrogen but it can still have mild oestrogenic effect. As we know, breast or ovarian cancer are related to excess oestrogen. Based on this theory soy may have anti-cancer properties (if it comes to oestrogen related type of cancers). I’m personally avoiding soy products on daily basis as the research is not conclusive and especially because of harmful effect on thyroid. I don’t mind having tofu or tempeh once in a while but it’s definitely not part of my regular diet.
2. Gluten and dairy
Both should be avoided especially in case of autoimmune thyroid conditions like Hashimoto’s or Grave’s disease. There is strong link between these two as both are highly inflammatory and can damage gut lining. If the gut lining is damage, undigested food particles will leak into the bloodstream and recognised by our body as foreign molecules. Gluten contains a protein called gliadin which is very similar to transglutaminase, an enzyme present in the intestines and in the thyroid. When gluten molecules leak to the bloodstream, your body will attack it. Because of the similar structure of gluten and thyroid enzyme, your body will attack not only foreign molecules but also your thyroid, slowly damaging it!
3. Cruciferous vegetables
Another popular one next to soy. Super healthy and important in liver detox but if its not cooked it’s high in goitrogens which inhibit iodine absorption. As you already know, low iodine levels can contribute to low thyroid. If you are intersted what else you can do to improve your liver detox click here.
Cruciferous vegetables include broccoli, brussels sprouts, spinach, kale, cauliflower etc. Because they are very nutritious, rich in antioxidants and support liver detox, I wouldn’t say cut them from your diet, but make sure you are not eating them too much and if you eat them, always cook the vegetables, even if its kale or spinach! Sorry no spinach based green smoothies. Instead you could replace spinach with rocket, celery or other greens i.e
Who doesn’t love peanut butter! It turns out that crucferrous vegetables are not the only source of goitrogens. Peanuts can disturb your thyroid function in similar way. Moreover, peanuts contain mould and aflatoxins – a toxic carciongenic compound. If you can, swap peanuts to other alternatives like hazelnuts or pecans.
It’s one of my favourite grain because of its alkalising properties. However, millet can also interfere with iodine absorption, hence impairing thyroid hormone production.
6. Nightshades and legumes
First group includes tomatoes, peppers and potatoes. They contain compounds called lectins and alkaloids. They can bind to your gut, disrupt digestion, and cause ongoing inflammation. Similar legumes – pretty high in lectins but the good thing is that soaking and cooking helps to reduce lectin content. Similar as gluten and dairy, I wouldn’t say they directly damage your thyroid but they do damage your gut lining and unfortunately healthy gut is fundamental for healthy thyroid. Also, gut bacteria assist in converting T4 to T3 which is active hormone that ultimately you need, not T4.
If you have serious thyroid problem, probably it’s worth considering to limit or exclude these food groups for some time. Otherwise just be mindful of their effect and your daily iodine intake. As I’m always saying everything in moderation is the golden rule:)