- Thyroid hormone is a substance that interferes with thyroid hormone synthesis, usually by blocking the thyroid's uptake of iodine.
- Cruciferous vegetables - cabbage, broccoli, cauliflower, kale , turnip, arugula, etc. - are particularly rich in a group of sulfur-containing compounds called glucosinolates, some of which are known Thyroid hormones.
- 's early research in iodine-deficient animals has shown that high consumption of cabbage or other cruciferous vegetables increases the incidence of goiter , so people with hypothyroidism are advised to avoid these healthy vegetables. A series of studies over the past two years dispelled these fears.
- Animal studies have shown that supplementation with broccoli or kohlrabi sprouts reduces inflammation and oxidative stress in the thyroid and improves thyroid function even in iodine deficiency-induced hypothyroidism.
- Two human studies show that supplementation with broccoli sprout extract (which is particularly high in isothiocyanates, the main goiter in broccoli) has no effect on thyroid function, even in people with autoimmune thyroid disease influences. The trend for improved thyroid function was even small, but not statistically significant.
- These studies convincingly demonstrate that cruciferous vegetables are a health-promoting food even for people with autoimmune thyroid disease and subclinical hypothyroidism.
The thyroid produces hormones that control metabolism and affect other vital systems in the body, such as the cardiovascular system , the immune system , and calcium homeostasis.
thyroid hormone can increase our basal metabolic rate, control appetite, improve the absorption of nutrients in the digestive tract, and control intestinal peristalsis.They play an important role in glucose metabolism and also stimulate fat breakdown.
Thyroid hormones even play an important role in regulating the immune system, so supporting optimal thyroid function for everyone is important for healing and overall health.
People with autoimmune thyroid disease and hypothyroidism (often with other autoimmune diseases) are generally advised to avoid cruciferous vegetables, spinach, radishes, peaches and strawberries , because of their goiterogenic properties.
Because eating cruciferous vegetables has been linked to multiple health benefits, including a reduced risk of cancer (even thyroid cancer!), this is an important topic to study in depth!
What are cruciferous vegetables?
Cruciferous vegetables (aka Brassicas) contain many vegetables that are highest in antioxidants, vitamins, and minerals, including:
- Arugula (rocket)
- Cabbage
- Broccoli
- Broccoli
- Broccoli, many varieties
- Brussels sprouts
- cabbage, many varieties
- canola /rapeseed
- cauliflower
- broccoli (gailan)
- kale
- radish
- wild pepper grass
- flowering cabbage
- cress
- horseradish
- kale, many varieties
- Kohlrabi
- Komatsu
- cress
- Maca
- mizuna
- mustard , many varieties
- Chinese cabbage (cooking)
- radish, many varieties Watercress
- Wild broccoli
Thyroid hormones in cruciferous vegetables
Cruciferous vegetables are particularly rich in a group of sulfur-containing compounds called glucosinolates. When raw vegetables are chopped or chewed, an enzyme called myrosinase is also present in these plants (by hydrolysis) to break down glucosinolate into a variety of bioactive compounds, many of which are potent anti- Oxidant , and is known to prevent cancer.The two antioxidant, anticancer classes of these glucosinolate hydrolysates are also known goitrogens. They are isothiocyanates and thiocyanates.
Isothiocyanates and thiocyanates block the activity of the thyroid peroxidase (aka thyroid peroxidase or TPO). TPO catalyzes the production of thyroid hormones through the "organization" of iodine, i.e. converting iodine ions into iodine atoms (by oxidation), so they can complex with amino acids (tyrosine) and then bind to thyroxine (T4), the thyroid gland Prohormone. (Then a group of selenium-containing enzymes called deiodinases (aka 5'-iodinases), found in various parts of the body, convert thyroxine into the more active thyroid hormone triiodothyronine (T3 ).) If the numbers are large enough, they reduce the formation of thyroid hormones by inhibiting TPO.
Despite the lack of human studies, early reports of goiters in iodine-deficient animals consuming large amounts of cruciferous vegetables have raised concerns that this vegetable family should be banned from people with hypothyroidism.
While there has never been strong evidence that cruciferous vegetables need to be avoided in the absence of iodine deficiency, a series of high-quality studies over the past two years has finally dispelled this fear.
Animal Studies
Animal models of hypothyroidism (caused by sulfadimethoxine that inhibits TPO activity or severe iodine deficiency) are invaluable for studying the underlying mechanisms of isothiocyanate and thiocyanate-induced goiter effects.
In a 2018 study, a diet of 7% freeze-dried rutabaga sprouts did not cause any significant changes in TSH, free T3 or free T4 in control (normal) rats.Excitingly, a diet supplemented with kohlrabi sprouts was protective against thyroid damage (significantly lower TSH) in iodine-deficient rats receiving an iodine-deficiency disorder (RDI) diet. In contrast, kohlrabi spray enhanced hypothyroidism (increased TSH and decreased free T3 and free T4) in sulfadimethoxine-treated rats. In a follow-up study, the results showed that kohlrabi sprouts reduced oxidative stress in the thyroid gland in the iodine deficiency or sulfamethoxazole groups (as shown by normalization of heme oxygenase-1, since my Ph.D. After studying HO-1, I found this especially interesting!) tended to decrease pro-inflammatory cytokines (TNF-α and IL-6) and increase anti-inflammatory cytokine IL-10. Importantly, this follow-up study showed that kohlrabi sprouts did not enhance hypothyroidism in sulfadimethoxine-treated rats.
In another rat study in 2018, a diet of 7% freeze-dried broccoli sprouts did not cause any changes in thyroid function in control rats, and also protected sulfadimethoxine-treated rats and Thyroid in severely iodine-deficient rats! In iodine-deficient rats, broccoli sprouts increased the antioxidant capacity of the thyroid gland while significantly reducing the levels of the proinflammatory cytokine IL-6. Broccoli sprouts decreased TSH and increased free T3 in sulfadimethoxine-treated rats. In addition, thioredoxin reductase activity was significantly increased in response to bud ingestion.
Thioredoxin reductase, a selenoenzyme, plays a key role in cellular redox regulation. Many chemical processes in the human body, including our cells' most basic energy use, are redox reactions , which means they involve the transfer of electrons from one molecule to another.These transfers require tight control, and thioredoxin reductase is one of the enzymes that achieves this (by reducing the electron donor thioredoxin). Also, thioredoxin reductase plays a key role in thyroid health.
While both too much and too little iodine has been linked to autoimmune thyroid disease, it is important to note the link between iodine and selenium in thyroid function. Too much iodine inhibits thyroid hormone synthesis; however, the body has an enzyme (sodium iodide symporter) whose job is to dispose of excess iodine to restore thyroid function as quickly as possible. Recent studies have shown that thioredoxin reductase cannot function if the enzyme is deficient, meaning that the link between excess iodine and autoimmune thyroid disease may actually be due to selenium deficiency (or at least part of it). ). It also helps explain why broccoli sprouts may help improve thyroid function even in the presence of iodine deficiency.
Taken together, these data suggest that cruciferous vegetable intake is not associated with thyroid health even in the presence of iodine deficiency. In fact, cruciferous vegetables can improve thyroid function!
Human Research
A 2019 human study confirmed that even high doses of isothiocyanates (from broccoli sprouts) are safe for the thyroid in the setting of autoimmune thyroid disease.
In this study, an aqueous extract of 3-day-old broccoli sprouts (made by simply boiling the sprouts for 30 minutes) was treated with myrosinase to convert glucosinolates into mainly sulforaphane (an isothiocyanate). The extract was then freeze-dried to form a powder and standardized for its sulforaphane content.This powder was mixed with pineapple and lime juice, so participants may not know if they received isothiocyanate concentrate broccoli sprout extract, untreated broccoli sprout extract (rich in glucosinolates precursor but without isothiocyanate) or without broccoli sprout extract. They took one dose a day for 84 days.
Broccoli sprout extract caused absolutely no changes in TSH, free T4 or thyroglobulin compared to placebo. The percentage of participants who were seropositive for TPO and/or thyroglobulin antibodies at baseline was not statistically significantly different at 84 days (with a slight downward trend, meaning those who met the diagnostic criteria for Hashimoto's thyroiditis at the end of the study) Fewer participants compared to the beginning). A similar trend for a decrease in the percentage of participants with subclinical hypothyroidism was observed (again, not statistically significant).
found similar results in a 2006 clinical trial in which participants drank a broccoli extract drink 3 times a day for 7 days and observed no changes in TSH, total T3 or free T4.
The take-home message
Taken together, these studies convincingly demonstrate that cruciferous vegetables are a health-promoting food. The thyroid produces hormones that control metabolism and affect other vital systems in the body, such as the cardiovascular system , the immune system , and calcium homeostasis. thyroid hormone can increase our basal metabolic rate, control appetite, improve the absorption of nutrients in the digestive tract, and control intestinal peristalsis. They play an important role in glucose metabolism,Also stimulates fat decomposition. Thyroid hormones even play an important role in regulating the immune system, so supporting optimal thyroid function for everyone is important for healing and overall health. People with autoimmune thyroid disease and hypothyroidism (often with other autoimmune diseases) are generally advised to avoid cruciferous vegetables, spinach, radishes, peaches and strawberries , because of their goiterogenic properties. Because eating cruciferous vegetables has been linked to multiple health benefits, including a reduced risk of cancer (even thyroid cancer!), this is an important topic to study in depth! What are cruciferous vegetables? Cruciferous vegetables (aka Brassicas) contain many vegetables that are highest in antioxidants, vitamins, and minerals, including: Cruciferous vegetables are particularly rich in a group of sulfur-containing compounds called glucosinolates. When raw vegetables are chopped or chewed, an enzyme called myrosinase is also present in these plants (by hydrolysis) to break down glucosinolate into a variety of bioactive compounds, many of which are potent anti- Oxidant , and is known to prevent cancer. The two antioxidant, anticancer classes of these glucosinolate hydrolysates are also known goitrogens. They are isothiocyanates and thiocyanates. Isothiocyanates and thiocyanates block the activity of the thyroid peroxidase (aka thyroid peroxidase or TPO). TPO catalyzes the production of thyroid hormones through the "organization" of iodine, i.e. converting iodine ions into iodine atoms (by oxidation), so they can complex with amino acids (tyrosine) and then bind to thyroxine (T4), the thyroid gland Prohormone. (Then a group of selenium-containing enzymes called deiodinases (aka 5'-iodinases), found in various parts of the body, convert thyroxine into the more active thyroid hormone triiodothyronine (T3 ).) If the numbers are large enough, they reduce the formation of thyroid hormones by inhibiting TPO. Despite the lack of human studies, early reports of goiters in iodine-deficient animals consuming large amounts of cruciferous vegetables have raised concerns that this vegetable family should be banned from people with hypothyroidism. Although there has never been strong evidence that cruciferous vegetables need to be avoided in the absence of iodine deficiency,But a series of high-quality studies over the past two years have finally dispelled that fear. Animal Studies Animal models of hypothyroidism (caused by sulfadimethoxine that inhibits TPO activity or severe iodine deficiency) are invaluable for studying the underlying mechanisms of isothiocyanate and thiocyanate-induced goiter effects. In a 2018 study, a diet of 7% freeze-dried rutabaga sprouts did not cause any significant changes in TSH, free T3 or free T4 in control (normal) rats. Excitingly, a diet supplemented with kohlrabi sprouts was protective against thyroid damage (significantly lower TSH) in iodine-deficient rats receiving an iodine-deficiency disorder (RDI) diet. In contrast, kohlrabi spray enhanced hypothyroidism (increased TSH and decreased free T3 and free T4) in sulfadimethoxine-treated rats. In a follow-up study, the results showed that kohlrabi sprouts reduced oxidative stress in the thyroid gland in the iodine deficiency or sulfamethoxazole groups (as shown by normalization of heme oxygenase-1, since my Ph.D. After studying HO-1, I found this especially interesting!) tended to decrease pro-inflammatory cytokines (TNF-α and IL-6) and increase anti-inflammatory cytokine IL-10. Importantly, this follow-up study showed that kohlrabi sprouts did not enhance hypothyroidism in sulfadimethoxine-treated rats. In another rat study in 2018, a diet of 7% freeze-dried broccoli sprouts did not cause any changes in thyroid function in control rats, and also protected sulfadimethoxine-treated rats and Thyroid in severely iodine-deficient rats! In iodine-deficient rats, broccoli sprouts increased the antioxidant capacity of the thyroid,At the same time, the level of the pro-inflammatory cytokine IL-6 was significantly reduced. Broccoli sprouts decreased TSH and increased free T3 in sulfadimethoxine-treated rats. In addition, thioredoxin reductase activity was significantly increased in response to bud ingestion. Thioredoxin reductase, a selenoenzyme, plays a key role in cellular redox regulation. Many chemical processes in the human body, including our cells' most basic energy use, are redox reactions , which means they involve the transfer of electrons from one molecule to another. These transfers require tight control, and thioredoxin reductase is one of the enzymes that achieves this (by reducing the electron donor thioredoxin). Also, thioredoxin reductase plays a key role in thyroid health. While both too much and too little iodine has been linked to autoimmune thyroid disease, it is important to note the link between iodine and selenium in thyroid function. Too much iodine inhibits thyroid hormone synthesis; however, the body has an enzyme (sodium iodide symporter) whose job is to dispose of excess iodine to restore thyroid function as quickly as possible. Recent studies have shown that thioredoxin reductase cannot function if the enzyme is deficient, meaning that the link between excess iodine and autoimmune thyroid disease may actually be due to selenium deficiency (or at least part of it). ). It also helps explain why broccoli sprouts may help improve thyroid function even in the presence of iodine deficiency. Taken together, these data suggest that cruciferous vegetable intake is not associated with thyroid health even in the presence of iodine deficiency. In fact, cruciferous vegetables can improve thyroid function! Human study A 2019 human study confirmed thatEven high doses of isothiocyanates (from broccoli sprouts) are safe for the thyroid, even in cases of autoimmune thyroid disease. In this study, an aqueous extract of 3-day-old broccoli sprouts (made by simply boiling the sprouts for 30 minutes) was treated with myrosinase to convert glucosinolates into mainly sulforaphane (an isothiocyanate). The extract was then freeze-dried to form a powder and standardized for its sulforaphane content. This powder was mixed with pineapple and lime juice, so participants may not know if they received isothiocyanate concentrate broccoli sprout extract, untreated broccoli sprout extract (rich in glucosinolates precursor but without isothiocyanate) or without broccoli sprout extract. They took one dose a day for 84 days. Broccoli sprout extract caused absolutely no changes in TSH, free T4 or thyroglobulin compared to placebo. The percentage of participants who were seropositive for TPO and/or thyroglobulin antibodies at baseline was not statistically significantly different at 84 days (with a slight downward trend, meaning those who met the diagnostic criteria for Hashimoto's thyroiditis at the end of the study) Fewer participants compared to the beginning). A similar trend for a decrease in the percentage of participants with subclinical hypothyroidism was observed (again, not statistically significant). found similar results in a 2006 clinical trial in which participants drank a broccoli extract drink 3 times a day for 7 days and observed no changes in TSH, total T3 or free T4. The take-home message Taken together, these studies convincingly demonstrate that even in people with autoimmune thyroid disease and subclinical hypothyroidism,Cruciferous vegetables are also a health-promoting food. citations Thyroid hormones in cruciferous vegetables
