The hypothyroidism diet is an interesting concept and varies depending on where a person lives. Those living in the developing world (mainly South Asia and Africa, but also parts of Europe) face a different reality to those living in the developed world. Thus the dietary focus for these two groups of people is quite different.
The hypothyroidism diet for most of the developing world – especially South Asia, Africa and parts of Europe focuses on the sufficient intake of the trace element iodine. In these countries iodine deficiency is the main cause of hypothyroidism. Iodine is present naturally in the soil and in seawater. People who live in areas which have iodine-poor soil or lack seafood in the diet (eg. inland, mountainous areas which lack outside sources of food) may suffer from iodine deficiency.
Thus for most of the developing world the hypothyroidism diet must contain sufficient iodine. The thyroid hormones thyroxine (T4) and triiodothyronine (T3) are produced in the thyroid gland by attaching iodine molecules to tyrosine – an essential amino acid. For adequate thyroid hormone production there must be adequate iodine in the diet. Hypothyroidism due to iodine deficiency causes an enlargement of the thyroid gland, also called goitre. Severe iodine deficiency in a pregnant woman can cause irreversible brain damage in the developing foetus, part of a syndrome called cretinism. In the early part of last century goitre was endemic (regularly found in a particular area or group of people) in parts of the US, known as the goitre belt. However the addition of iodine to table salt has virtually eliminated iodine deficiency and goitre in these areas. At one time cretinism was endemic to Switzerland and in fact thought to be genetic. Again the incidence decreased with the dramatic improvement in the diet in this area.
Iodine is a trace element, a micronutrient which is required in only minute amounts in the diet. About 150 µg per day is sufficient, except in pregnancy and breastfeeding where higher doses are required (about 220µg and 290 µg per day respectively). The hypothyroidism diet should include this amount daily to avoid insufficient thyroid hormone production due to dietary iodine deficiency. Iodised table salt will provide sufficient iodine for daily needs (approximately 400 µg per teaspoon).
Good sources of iodine for the diet include saltwater fish and sea vegetables such as seaweed (various forms including kelp and nori – found in sushi). Other sources of iodine include milk and egg yolks.
Interesting Questions about Thyroid:
Thyroiditis is an inflammation of the thyroid gland. Thyroiditis can cause either hyperthyroidism or hypothyroidism, or one followed by the other. It can also cause a goiter, an abnormal swelling in the neck due to an enlarged thyroid. It affects about 12 million people in the United States.
Thyroiditis is the most common cause of hypothyroidism. When patients with thyroiditis have any symptoms, they are usually the symptoms of hypothyroidism. It is also common to have an enlarged thyroid that may shrink over time.
The type of thyroiditis seen most often is Hashimoto’s thyroiditis, a painless disease of the immune system that runs in families. Hashimoto’s thyroiditis affects about 5% of the adult population, increasing particularly in women as they age.
Another form of thyroiditis affects women of childbearing age. Postpartum thyroiditis occurs in 5%-9% of women soon after giving birth and is usually a temporary condition.
Viral and bacterial infections can also cause thyroiditis.
How does thyroid disease affect my cholesterol level?
One of the observed side effects of hypothyroidism is an elevation of LDL cholesterol, the “bad cholesterol.” Elevated LDL levels have been associated with heart disease, particularly coronary artery disease, and peripheral vascular disease. Elevated triglycerides also pose a serious medical problem. However, only in the most severe cases of hypothyroidism does the disease cause a marked elevation in triglyceride levels.
The “good cholesterol” is called HDL cholesterol. Scientific studies are inconclusive about the effects of hypothyroidism on HDL levels. Some have shown a decrease; others have shown no change; and a few have shown a minimal increase.
All patients with hypercholesterolemia (high cholesterol) should have tests of their thyroid function since a small percentage of these patients will have hypothyroidism contributing to their cholesterol problem. Treatment with thyroid hormone will lower cholesterol levels in those patients with an abnormal cholesterol from hypothyroidism.
The overall effect of hypothyroidism is a significant increase in the bad cholesterol. Long-standing, untreated hypothyroidism can lead to permanent damage to the coronary arteries and other blood vessels. Therefore, it is important to treat hypothyroidism and monitor cholesterol levels closely.
A goiter is an abnormal swelling in the neck caused by an enlarged thyroid gland. It can become quite large. The problem occurs in at least 5% of the population.
Worldwide, the most common cause of a goiter is lack of iodine, a chemical which the thyroid uses to produce its hormones. About 100 million people don’t get enough iodine in their diets, but the problem has been solved in the United States and most developed countries by adding iodine to salt.
Even with the right amount of iodine, the thyroid gland can swell, creating a goiter. This can occur in any type of thyroid disease, including hyperthyroidism, hypothyroidism, thyroiditis, and thyroid cancer. Many goiters develop with normal thyroid hormone levels and do not require treatment.
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Hypothyroidism that is not due to dietary deficiency of iodine will not respond to iodine replacement. This is the second scenario and thyroxine replacement in the form of synthetic thyroxine tablets is required. Although it is still important to maintain sufficient iodine in the diet as well, there are some additional considerations. A good hypothyroidism diet in this situation is explained further below.
Synthetic thyroxine hormone is best taken on an empty stomach as absorption is increased in the fasting state. Some substances that interfere with the absorption of synthetic thyroxine include dietary fibre, soy and iron and calcium supplements. It is important to check for these substances in multivitamins. The calcium contained in milk can also bind thyroxine and reduce its availability for absorption.
Other medications that interfere with absorption include antacids which contain magnesium and aluminium, and some cholesterol-lowering medication like cholestyramine and cholestipol. Sucralfate which is used to treat stomach ulcers will also reduce thyroxine absorption.
The diet does not eliminate the above substances. Rather it is important not to take thyroxine replacement tablets in combination with them. It is best to allow several hours to pass before or after taking thyroxine and the abovementioned foods and medications.
The hypothyroidism diet thus depends on adequate dietary iodine. For those with hypothyroidism not due to iodine deficiency, thyroxine replacement is necessary. Care must be taken with foods and medications that are taken concurrently.