The thyroid is a butterfly-shaped gland at the front of the neck (near the Adam's apple in the case of men), which makes and releases two hormones: T4 (thyroxine) and T3 (triiodothyronine).
Thyroid hormones control metabolism, or the rate at which every part of the body works. To make these hormones, the thyroid captures and concentrates iodine from our food.
What can go wrong with the thyroid?
Thyroid disorders can range from a small, harmless goitre (enlarged gland) to cancer. The most common thyroid problem involves an abnormal production of thyroid hormones.
An over-production of these hormones results in hyperthyroidism. An under-production can lead to hypothyroidism.
Who is most at risk of thyroid disorders?
Women are five times more likely to develop thyroid disorders, especially those aged between 20 and 50.
What is the most common thyroid disorder in Singapore?
Grave's disease, which is an autoimmune disorder, said Professor Lee Kok Onn, the head of the division of endocrinology at National University Hospital. The body's immune system produces abnormal antibodies which stimulate the thyroid gland, causing an over-production of hormones.
It is estimated to affect about 1.28 per cent of people here.
Should people with hypothyroidism avoid soya?
Soya has been thought to interfere with the body's ability to absorb thyroid hormone supplements, which are used to treat hypothyroidism.
However, there is no evidence that people with hypothyroidism should avoid soya completely, reported the Mayo Clinic in the United States on its website.
Still, it is best to wait four hours after taking thyroid medication to consume any products that contain soya, the report said.
Does iodine intake affect the thyroid?
Iodine is found in foods like seaweed and seafood.
Contrary to popular belief, iodine-rich foods do not alleviate thyroid disorders, said Dr Daphne Khoo, the head and senior consultant in the department of endocrinology at Singapore General Hospital.
Extra iodine is only useful in iodine-deficiency goitre, which is a condition rarely seen here as people have enough iodine in their diet.
In both Graves' Disease and another thyroid-linked condition, Hashimoto's Thyroiditis, extra iodine may actually aggravate matters.
What is Graves' Disease and Hashimoto's Thyroiditis?
Graves' Disease, named after its discoverer, Irish physician Robert J. Graves, is an autoimmune disorder that leads to overactivity of the thyroid gland, or hyperthyroidism.
Hashimoto's thyroiditis, named after Japanese doctor Hakaru Hashimoto, is also an autoimmune condition where the body attacks the thyroid, causing it to be underactive, often leading to hypothyroidism.