Broccoli, cabbage, cauliflower, and kale are considered "health stars": Rich in fiber, vitamins, and antioxidants. But time and again, the same question arises: Is it possible that cruciferous vegetables, of all things, could impair thyroid function? A listener on the program raised an even more focused point – whether heating broccoli reduces the substances that might affect the gland, and whether this changes the recommendation to eat it.
This concern is based on a group of natural substances in cruciferous vegetables, which under certain conditions are capable of affecting the body's utilization of iodine – an essential component for the proper functioning of the thyroid gland. From this, quite a few myths were born: That it is better to avoid raw broccoli, that cabbage is "dangerous" for those with an underactive thyroid, and that cooking solves the problem completely.
But as a scientific advisor to the Plant Board, it is important for me to emphasize: The effect of those substances depends on the amount consumed, the method of preparation, the nutritional status of the individual – and especially on the availability of iodine in the diet. Heating also plays a role: It changes the activity of the enzymes in the vegetable, and sometimes reduces some of the active substances, but does not "eliminate" them completely.
So should we be worried about cruciferous vegetables? Is it better to eat them cooked? And who really has a reason to pay attention to quantities? The answers are not clear-cut but they do make it possible to understand how to enjoy their health benefits without unnecessary worry.
Effect on the thyroid gland: In the past, there were studies showing that cruciferous vegetables contain substances that adversely affect the thyroid gland and interfere with the production of hormones responsible for our metabolism; on the other hand, there were also other studies showing that it is actually important to consume cruciferous vegetables if there is thyroid underfunction, because cruciferous vegetables contain other substances necessary for its function.
– cooking and baking or any heating reduces the amount of these substances.
– people who are treated with thyroid medications, and are balanced in their blood tests – can behave like any person who has no functioning problem and consume cauliflower/broccoli and derive the nutritional benefit from them. The only ones who probably need to pay attention are those who are not medicated and are not balanced.
What belongs to the cruciferous family?
– cabbage.
– cauliflower.
– broccoli.
– kohlrabi.
– turnip.
– radish, small radish.
– kale.
– Brussels sprouts.
A few important points about cruciferous vegetables:
– the cruciferous vegetables are called cruciferous because the flowers of the plants in this family contain 4 petals arranged in the shape of a cross.
– these vegetables contain many antioxidants, as well as iron, calcium, and dietary fiber. It is not mandatory to integrate them into the diet because all these components are also found in other vegetables, but their addition to our menu undoubtedly upgrades and adds health-wise.
– the cruciferous vegetables contain a type of dietary fiber that is not broken down by our digestive system, and then when they reach the large intestine – the good bacteria "eat" these substances and in the process ferment and create gases, which causes bloating. These gases have a characteristic odor because cruciferous vegetables also contain a large amount of sulfur, which is known to have a strong odor.
Do they cause gas? In some people these vegetables cause gas; these gases are created solely because of fermentation by good intestinal bacteria – which "love" these vegetables and "celebrate" on them when they reach the intestines.
According to studies, in most people regular consumption of these vegetables causes adaptation of the intestines in terms of the bacterial population, and then there is no fermentation and gases (except if they are consumed "sometimes" and then there is no adaptation).
In conclusion, the important message: Cruciferous vegetables like broccoli, cabbage, cauliflower, and kale contain substances that can, in certain amounts, affect the utilization of iodine in the thyroid gland. Heating reduces some of these substances, but does not completely disappear them.
People who are medicated and balanced can consume them without fear. These vegetables are rich in antioxidants, fiber, and minerals, and those who eat them regularly usually also adapt to the bloating they may cause. Ultimately, it is advisable to integrate them into the daily menu in a mindful way according to personal status.