Are Goitrogens Slowing Down Your Thyroid?

written by Cassie-Lee Tario


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Eating healthy seems to be pretty straight forward to some people- eating whole foods, fruits and vegetables and staying away from boxed anything.   But is it really that easy? 

When dealing with certain health issues we need to look past just the simplicity of “healthy” eating and look more in depth to the way the food is interacting with our bodies.


Your Thyroid

When dealing with thyroid issues eating healthy is a whole other ball game.  There are actually foods that will interfere with the way your thyroid functions and therefore should be eliminated or consumed with caution.   These foods are usually referred to as goitrogens, which comes from the term goiter.  Goiter is a condition in which the thyroid gland becomes enlarges.  The thyroid creates the T4 hormone which gets converted to T3 which every cell, organ and muscle depends on in your body.   T3 is responsible for determining the speed at which processes happen inside your body, which impacts your body temperature, weight, energy level, and mood. 


When a thyroid gland becomes enlarged it is usually because it is trying to overcompensate for its trouble creating hormones properly.    This is where goitrogens should be avoided because of their compound that creates even more difficulty for the thyroid to create its hormones properly.  Although there is no hard evidence that goitrogens affect your thyroid health, it is usually suggested to not eat them excessively.

Which Foods Disrupt Your Thyroid Function? 

There are two main groups of foods that have be associated with disrupting the thyroid hormone and these are soybean products and cruciferous vegetables.  Soybean products contain the soy bean itself as well as things made from soy beans such as tofu or tempeh.  When it comes to soy, you really have to read the labels because it seems to sneak into a lot of our packaged foods.  Don’t get me wrong, soy can have beneficial components to it, but when it comes to the thyroid we are look at one specific substance it contains.  This component is the isoflavones, which is the part of soy that has been linked to  decreased thyroid hormone output. 

The way this substance works against the thyroid is that it blocks the activity of the enzyme thyroid peroxidase.  This enzyme adds iodine to the thyroid hormone.  A proper thyroid hormone must have three to four iodine atoms added to its structure to properly function. 

The cruciferous vegetables, which is the other group that affects thyroid production, contains broccoli, cauliflower, Brussels sprouts, cabbage, mustard, rutabagas, kohlrabi and turnips.  In these is a substance called isothiocyanates, which has the same action as the isoflavones, where they block the activity of the enzyme thyroid peroxidase.  This substance also disrupts messages that are sent across the membrane of the thyroid cell.


What Should I Do? 

The list of foods that contain goitrogens are: broccoli, Brussels sprouts, cabbage, cauliflower, kale, peaches, radishes, strawberries, kohlrabi, mustard, rutabaga, turnips, millet, peanuts, spinach and soy products.  Heating or cooking these foods may help to inactivate the goitrogen compounds in them but then you may also lose the vitamin and mineral content in them.  In general goitrogens are not bad, these foods actually have a lot of benefits that might even outweigh this flaw, especially if you do not have a compromised thyroid.  My advice is to not over consume them.  A recommendation may be no more then a cup of these foods, four times a week and when dealing with thyroid issues to consume with caution.


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Cassie-Lee Tario is currently finishing up her schooling to become a Certified Nutritional Practitioner.  She believes that being healthy isn’t just about eating vegetables it’s living a whole lifestyle and she is excited to help inspire people on the road to their healthier lifestyles!  You can read more from Cassie-Lee on her blog.  She can also be found online through facebook  and twitter.