A number of patients have asked if thyroid patients should not eat cruciferous vegetables such as cabbage, cauliflower and radish?
Here we address this question.
First of all what are cruciferous plants?
The main ones are.
1, attributed to the genus Brassica cabbage, cauliflower (cauliflower), green cauliflower (broccoli), cabbage, cabbage, bok choy, rape, a variety of kale, watercress (bean curd), mustard, squash, red cabbage, large head of cabbage, turnips, etc.
2.Radish, daikon radish, red radish, water radish, heart radish, etc., which belong to the genus radish.
3, some people’s favorite wild vegetables, such as shepherd’s purse, Zhuge, crushed rice shepherd’s purse, solanum, arugula, etc.
4.Mustard (seeds of mustard), horseradish, etc., which belong to seasoning.
5.There are also some herbs that belong to the cruciferous family, the most common ones such as Panax quinquefolium and Lycopodium (seeds of radish).
6, flowers in the violet is also cruciferous.
So why do you say you can’t eat it?
Research shows that cruciferous plants have a class of antioxidant substances – thioglycosides, under certain conditions, thioglycosides will be hydrolyzed to generate isothiocyanates. Thiocyanate is a goitrogenic substance, and the goitrogenic effect works by competitively inhibiting the activity of the iodine-sodium transporter (NIS), which in turn inhibits thyroid iodine uptake and leads to a decrease in thyroxine (T4) concentration. Over time, this results in impaired production of thyroid hormones in the body, leading to goiter.
This effect occurs only at relatively high plasma thiocyanate concentrations (4.8-6.4 mg/L), while thiocyanate concentrations in most of our regional populations are well below this value. In contrast, populations in some iodine deficient areas (when iodine intake is below 100ug per day) can result in a relatively low thiocyanate/iodine (SCN/I) excretion, and such a low excretion ratio can lead to increased thyroid stimulating hormone (TSH) levels and lower thyroxine (T4) concentrations.
Some flavonoids also strengthen the role of thiocyanate inhibition in the thyroid gland. Some fruits that we usually eat, such as oranges, pears, apples and grapes contain flavonoids that are broken down by bacteria in the intestine, which can strengthen thiocyanate inhibition of iodine absorption, but this strengthening effect is also not obvious as long as the fruit is not eaten immediately after consuming cruciferous vegetables such as radishes and broccoli.
Another factor that increases the concentration of thiocyanate in the body is smoking. In addition, the average iodine content in breast milk of women who smoke is 52% less than that of women who do not smoke, which confirms that thiocyanate inhibits the secretion and transport of iodine from the mammary glands.
In summary, there are four reasons for high thiocyanate content in the body, which leads to goiter: 1) consumption of large amounts of cruciferous foods rich in thiocyanate in a short period of time (equivalent to 500g-1000g of broccoli, radish, cabbage, etc. per day); 2) being in a low iodine area, unable to eat seafood and iodized salt; 3) consumption of cruciferous and flavonoid-rich fruits at the same time; 4) heavy Smoking. Generally, at least three of these conditions must be met at the same time before people need to pay attention to this problem.
Which thyroid patients should avoid cruciferous foods?
People who need to pay attention to.
1, smoking people: the thiocyanic acid content in the body of smoking people is significantly higher than that of non-smoking people, so the probability of suffering from goiter is also much higher than normal people, such people should pay due attention to cruciferous foods if consumed in large quantities. Of course, cruciferous foods, such as broccoli and purple kale, contain a lot of antioxidants and are also very healthy foods for people who smoke. The best way to deal with this is to eat more of these foods appropriately after quitting smoking to improve the body’s antioxidant capacity.
2.Patients with simple goiter: These people are mainly located in iodine-deficient areas and have been unable to consume iodine-containing foods for a long time, but with the popularization of iodized salt for all, such people are rare.
3. Patients before receiving 131 iodine treatment: including patients with hyperthyroidism and differentiated thyroid cancer. Because the mechanism of action of thiocyanate is to competitively inhibit the iodine uptake function of the thyroid gland, it is necessary to avoid such foods before receiving 131 iodine treatment, otherwise the treatment effect will be affected. It should be especially reminded that because cruciferous plants have powerful anti-cancer and antioxidant effects, patients with thyroid cancer and hyperthyroidism should eat more of them, which will help them recover from the disease as soon as possible.
4, some patients with thyroiditis: patients with thyroiditis are sick due to the destruction of thyroid cells caused by various reasons, and the process of repairing thyroid cells and functions requires the participation of a large amount of iodine. At the same time, many patients with thyroiditis themselves develop the disease due to excessive generation of free radicals in the body and their own destruction of thyroid cells, so they also need a large amount of antioxidant nutrients. Therefore, it is best to consult your doctor for specific consumption advisories.
In addition to the above-mentioned categories of thyroid disease patients who need to avoid cruciferous vegetables under special circumstances, patients with hyperthyroidism, hypothyroidism, thyroid nodules and thyroid cancer should increase the intake of these foods. Especially for people who often eat seafood in coastal areas, eating cruciferous plants can effectively reduce the stimulating effect of high iodine on the thyroid gland, and the large amount of antioxidants in them can protect the cells of the whole body from various toxic substances.