Should patients with thyroid disease supplement iodine?

*It is only for medical professionals to read for reference.
Some people say that iodine should be supplemented, and some people say that iodine cannot be supplemented! How should patients with thyroid disease eat? I went to see the doctor again, thyroid nodules, and asked the doctor what needs to be paid attention to in the diet.
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Endocrinologist: "Be careful not to eat fat!" Clinically, both the patient and the doctor should have suffered from the thyroid gland.
It is distressed to pay attention to the diet of diseases.
Whether these foods can be cured by eating too much as the rumors say, or whether they can be sick by eating too much, eating more is considered more, and eating more is considered less, it is really silly and confused.

This article sorts out some common thyroid diseases and related diet studies, hoping to make us less detours in the treatment of thyroid diseases.

Hypothyroidism Hypothyroidism (hypothyroidism) is divided into clinical hypothyroidism and subclinical hypothyroidism in terms of degree.

The causes of hypothyroidism include autoimmune damage, surgical removal of the thyroid gland, radioactive iodine destruction, external radiation, iodine deficiency or iodine excess, etc.

If the patient has hypothyroidism due to complete removal or complete destruction of the thyroid gland, they will generally take levothyroxine (L-T4) for treatment.

Many foods will affect the intestinal absorption of levothyroxine [1], but the consumption of iodized or uniodized salt has no significant effect on the thyroid.

However, it is recommended that patients with hypothyroidism can take the medicine before going to bed, because taking L-T4 for the treatment of hypothyroidism is effective and safe, and it helps to alleviate the symptoms of patients and restore normal thyroid hormone levels [2].

If the patient's thyroid gland has been removed or the thyroid tissue is still left, a normal iodine-containing diet can be carried out, including eating iodized salt.

In general, hypothyroidism caused by iodine deficiency often occurs in iodine-deficient areas, and eating iodized salt is the most effective method.

The degree of hypothyroidism caused by excess iodine is relatively mild.
The most common one is subclinical hypothyroidism.
At this time, it is necessary to find the cause of excess iodine and limit iodine intake, such as avoiding drinking high-iodine water or eating too much iodine-rich food.Hyperthyroidism Hyperthyroidism (hyperthyroidism) patients accounted for 1.
3% of the total population [3], a considerable group, and the main cause of hyperthyroidism is toxic diffuse goiter (Graves disease), serum thyroid stimulating hormone antibody Can induce or aggravate Graves disease.

The trace elements iodine and selenium in the diet can regulate the content of these thyroid-related antibodies.

Therefore, clinically, patients with thyroid nodules should be reminded to control their daily iodine intake levels and review them in time to reduce the risk of hyperthyroidism induced by excessive intake of iodine.

Thyroid nodules Thyroid nodules are generally found through imaging examinations, and the malignant rate is 7%-15% [4].

The clinic judges whether needle biopsy is needed based on the size of the nodule and the imaging characteristics.

If it is highly suspected to be a malignant nodule, or a benign nodule that has compressed the neck, surgical resection of the thyroid can be performed; if a biopsy reveals a benign or non-suspect nodule, the patient is generally scheduled for regular ultrasound follow-up.

Thyroid nodules are generally recommended to follow up @originoo regularly.
At this time, the patient will say: "Doctor, can I eat iodized salt and seafood like this.
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?" Regarding the dietary taboos of patients with thyroid disease, the following will pass.
Some food classification answers that are often asked.

Don't be afraid of iodine-containing foods.
Iodine deficiency is not a good thing.
Iodine is the closest friend of the thyroid.
When iodine enters the body, it will be firmly grasped by the thyroid and synthesize the body's life fuel-thyroid hormone.

The relationship between iodine and thyroid disease is in a "U"-shaped curve.
Excessive or lack of iodine will affect thyroid function.

Therefore, excessive iodine and iodine deficiency will not work! The World Health Organization (WHO) recommends that healthy adults (non-pregnant women) need to consume 150-200 micrograms of iodine per day, and women during pregnancy and lactation should ensure at least 250 micrograms of iodine per day.

Hospitals generally determine the iodine content in the human body through urine iodine determination.
Generally, it is considered that the iodine content is between 100-200 mg/L as the appropriate state. Regarding the dietary intake of iodine, according to clinical experience, a normal diet can maintain sufficient iodine intake.
People with special dietary habits, such as vegetarians, are at greater risk of insufficient iodine intake, because vegetables are not foods that are rich in iodine.
[5].

In addition, a pill called "Iodine for Thyroid Health" is sold in pharmacies.
The single dose of this medicine is hundreds of times the recommended daily intake of iodine.

Because excessive iodine supplementation can not improve the condition of thyroid disease, it will affect the thyroid function [6].
Generally, it is not recommended for patients to buy and use this medicine and those health products that claim to be "good for the thyroid": such as spirulina, kelp tablets, etc.
.

The American Thyroid Association recommends avoiding supplements with iodine content> 500μg/d [7].

In addition, seafood is also a major source of iodine supplementation for the human body.
According to the iodine content, it is divided into three categories: seafood is a major source of iodine supplementation for the human body @originooHigh iodine content: kelp, seaweed and other algae; medium iodine content: shrimp, Scallops; low iodine content: hairtail, salmon, small yellow croaker, etc.

So how should patients with thyroid disease take iodine? After treatment for patients with hyperthyroidism, if the thyroid function is not normal or accompanied by goiter, excessive intake of iodine will make the condition worse.
At this time, the "iodine-free" diet must be taken; if the thyroid function is already normal, the thyroid gland is not obvious If you are swollen and want to eat seafood, you can choose small yellow croaker, hairtail, and cuttlefish with less iodine.
Once a week is acceptable.
Use iodized salt when cooking.

For those with simple thyroid nodules, it is best to choose seafood after measuring the iodine content in their own body.

Regarding Hashimoto's thyroiditis, long-term high-iodine diet may induce the disease, which can occur in several generations of the same family due to genetic factors.

It is recommended that children of patients with Hashimoto's thyroiditis reduce their iodine intake, check thyroid function if necessary, and prevent it in advance [8].

To sum up, patients with goiter and hyperthyroidism do not need to "sniff the color of iodine", and rationally evaluate the intake based on the condition of the disease.

Goiter: Which foods contain? The pathogenic mechanism of goiter is that goiter preferentially combines with iodine in the blood, resulting in insufficient iodine source for thyroxine synthesis, leading to compensatory hyperplasia and swelling of the thyroid.

The most common foods that cause goiter are cruciferous vegetables and soy products.

▎ Cruciferous vegetables Common cruciferous vegetables in life include broccoli, cabbage, radish, broccoli, kale, etc.
These plants contain an antioxidant called glucosinolate, which is hydrolyzed in the human body It produces isothiocyanate, which is a goiter-causing substance.

However, cruciferous vegetables are not useless.
Glucosinolate hydrolyzate has anti-cancer properties and is beneficial to human health [9].

The current research results of common cruciferous vegetables @originoo suggest that long-term intake of cruciferous vegetables in humans may cause disorders of thyroid hormone production and cause goiter, but there is no rigorous research to support them should be stopped.

If the following situations occur, it is recommended to seriously consider the problem of cruciferous vegetables causing goiter: eating a large amount of cruciferous vegetables in a short period of time is equivalent to eating 2 kg of broccoli, radish, cabbage, etc.
a day; eating cruciferous vegetables at the same time, Have a history of heavy smoking, or be in a low-iodine area and cannot eat seafood and iodized salt, or eat flavonoid-rich fruits (apples, pears, grapes, oranges) at the same time.

Otherwise, patients with thyroid disease can properly consume cruciferous vegetables, especially those who often eat seafood and those living in coastal areas, which can effectively reduce the stimulating effect of high-iodine diet on the human thyroid [10].

Beans and soy products: The most overlooked diet soy products are common dishes in most southern regions, including soy milk, tofu, soy sauce, tempeh and miso.

Because it is common, it makes patients ignore the impact of soy products on thyroid function.

Most soy products contain isoflavones, which are inhibitors of thyroid peroxidase and can reduce the synthesis of thyroid hormones.

Some researchers have suggested that the daily dietary intake of legumes or soy products will increase the personal risk of hypothyroidism.
Patients with hypothyroidism may need to take larger doses of thyroxine after using legumes. Unexpectedly, the national breakfast may also hurt the thyroid! Research by @originoo shows that in areas where iodine is sufficient, people with normal thyroid function have no abnormalities in serum thyroid function after consuming soy products [11].
Special attention is needed if soy formula milk powder is given to children with congenital hypothyroidism.
Increase the dose of levothyroxine to ensure that children's thyroxine needs are met [12].

Although it is necessary to pay attention to the intake of soy products, clinical studies do not have sufficient evidence to require adult patients with hypothyroidism to fast soy products.
It is reasonable for patients to eat soy products normally (but don't eat too much!).

Other trace elements ▎Selenium Selenium is an important trace element that affects the metabolism of thyroid hormones.
It is rich in seafood and animal organs.
It can also meet the intake of selenium by eating bread, grains, meat, poultry, fish and eggs.
Into.

The Health Industry Standards of the People's Republic of China issued in 2017 recommends that the average daily selenium requirement for adults is 50μg, and the maximum intake is 400μg.

Selenium poisoning is not common clinically.
Symptoms include nausea, discoloration of nails, brittleness, shedding, hair loss, fatigue, irritability, and bad breath (often called garlic bad breath).

Some studies have shown that appropriate selenium supplementation can improve the condition of patients with autoimmune thyroid diseases; the increased risk of goiter and thyroid nodules in European women may be related to selenium deficiency; [13] Daily intake of selenium is allowed up to 100μg [14], but current research does not support routine selenium supplementation for patients in the treatment of Graves disease, lowering serum thyroid antibody levels or maintaining normal thyroid function.

[15, 16] However, in clinical practice, patients are generally not required to supplement selenium simply for the treatment of thyroid diseases.
However, the European Thyroid Association and the European Group of Graves ophthalmopathy recommend that patients with mild Graves ophthalmopathy be supplemented with selenium for a period of 6 months.
Thereby improving the patient's quality of life during the period of illness and after the recovery of the eye disease.

[17]▎Zinc, copper and magnesium Currently, the role of zinc, copper and magnesium in the synthesis and metabolism of thyroxine is not clear.

A meta-analysis of 8 studies suggests that there is a correlation between selenium, copper and magnesium and thyroid cancer.

[18] The results of the US National Health and Nutrition Survey (2011-2012) suggest that the correlation between zinc, copper and selenium and human serum free thyroxine or total thyroxine levels is not consistent.

[19] Based on the existing research evidence, we do not recommend supplementing zinc, copper, and magnesium simply to improve thyroid function.

Regarding the question about dietary attention of patients with thyroid disease, it is a false proposition to judge whether a food can be eaten or not by leaving the quantity.
The correct dietary attention should be based on understanding the basis of the disease.
It is determined by the intake and relevant clinical indicators.
I hope this article can help you avoid the minefield of "thyroid disease diet" and achieve a balanced diet and a healthy life. References: [1] Liwanpo L, Hershman JM.
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Abstract