The role of the thyroid gland

The thyroid gland is located in the front of the neck below the larynx. The hormones of the thyroid gland regulate metabolism in every cell in the body by regulating energy production, temperature control, oxygen uptake and repair of every cell in the body.

It does this by the production of two hormones, triiodothyronine (T3) and throxine (T4). T3 is the more active hormone and it is made by the conversion of T4, which is less metabolically active. Thyroxine is made up of two tyrosine rings (tyrosine is an amino acid) with four iodine atoms attached. In order to be converted to the active form (T3) an iodine atom must be removed. This conversion process is reliant on enzymes, which are made from selenium. A problem with the thyroid function can affect nearly all bodily functions.

Thyroid problems

This term refers to an underactive thyroid.  A lack of thyroid hormones could be due to an inability to produce the hormones or could be a problem related to the pituitary gland.  The pituitary gland secretes a hormone that stimulates the thyroid gland (thyroid stimulating hormone – TSH).  If the level of thyroid hormones in the blood falls, the pituitary secretes TSH.  A blood test that shows that thyroid hormones levels are low and TSH levels are elevated can mean that the thyroid is not functioning properly.  This is termed primary hypothyroidism.  If both thyroid hormone levels are low and TSH levels are low this is called secondary hypothyroidism and indicates that the pituitary gland is not functioning properly. However most cases of hypothyroidism are primary. Hypothyroidism is 7 times more common in woman than men.

Symptoms of hypothyroidism

  • Sensitivity to cold (cold hands and feet)
  • Weigh gain/difficulty losing weight
  • Menstrual problems
  • Dry skin
  • Hair loss
  • Depression
  • Fatigue
  • Muscle and joint pain
  • Recurrent infections
  • Headaches
  • Loss of libido
  • Increased risk of heart disease (since cholesterol and triglcyeride levels increase)

This term refers to an overactive thyroid and means the body is overproducing thyroid hormones.

Symptoms of hyperthyroidism

  • Fast pulse
  • Hyperactivity
  • Bulging eyes
  • Weight loss/difficulty in gaining weight
  • Insomnia
  • Irritability
  • Menstrual problems
  • Nervousness

Causes of thyroid problems

  • Iodine deficiency, Iodine is needed to produce the thyroid hormones. 
  • Excessive consumption of goitrogens (turnips, peanuts, broccoli, brussell sprouts, cabbage, mustard, peanut, walnuts, millet, soya beans) can lead to iodine deficiency as they block the utilisation of iodine. 
  • Over consumption of iodine – this can cause both hyperthyroidism and hypothyroidism. Iodine is needed by the thyroid to make the thyroid hormones.
  • A lack of tyrosine, iodine and selenium in the diet are possible causes. Hypothyroidism is far greater in land-locked countries, where less iodine rich seafood is consumed.
  • Failure to convert T4 to T3 maybe due to insufficient selenium.
  • An imbalance in adrenal hormones may also be a cause. When we are under stress the thyroid slows down to compensate for an excess of adrenal hormones, this is how chronic stress affects thyroid functioning.
  • Failure of cells to take up thyroid hormones. In order for the thyroid hormones to perform their functions the target cells must take them up effectively. This relies on receptor sites on the cell membranes. Excess saturated fat in the diet has a negative effect on cell membrane health making them more rigid. However, fats such as omega 3 and 6 fats are highly beneficial, and help communication between the hormones and the cells.
  • Environmental toxins. These can be divided into several categories, all of which prevent the correct functioning of the thyroid. Firstly, heavy metals, such as lead, excess iron, cadmium, fluoride and mercury. Fluoride is often added to our water supply, and has been shown to have a negative effect on the thyroid. Mercury fillings have also been shown to suppress thyroid function. Secondly, many types of medication suppress the thyroid, these include: barbiturates, lithium, salicylates, and cortico-steroids (often prescribed for asthma). Lastly, several foods can also affect thyroid function. These have been named 'goitregens' and largely consist of the brassica group of vegetables. Brassicas include: turnips, cabbage, broccoli and brussell sprouts, however cooking them does destroy the inhibitory compounds within them, so these foods should only be avoided in their raw form. Some soya products also slow down the thyroid, due to their oestrogen raising qualities. High oestrogen inhibits the thyroid. Tea is commonly grown in fluoride rich soil and is believed to have a suppressive affect on the thyroid.
  • Iron supplements if on thyroid medication, this can lead to increased symptoms of hypothyroidism.
  • Massive doses of vitamin C or the B vitamin PABA, can alter the function of the thyroid gland
  • Overdosing on the amino acids cysteine or glutathione
  • Chemicals and waste products from manufacturing processes
  • Plastics e.g. water in plastic bottles
  • Fluoride
  • Drugs e.g. aspirin, steroids. If you are hyperthyroid you should avoid medication, which can increase your heart rate further

Thyroid test

A blood test can reveal thyroid problems. However, milder cases of thyroid problems are often not shown in a blood test. In this case taking basal body temperature is an effective way of testing thyroid function.  The basal body temperature is the lowest temperature the body reaches and is taken on waking in the morning.

How to take your basal body temperature

  • Place a thermometer by your bed before you go to sleep
  • On waking, place the thermometer under your armpit for ten minutes, (if using a mercury thermometer) or if using a digital thermometer until it bleeps or the figure stops flashing
  • You must be at rest while this is taking place with your eyes closed
  • Record the temperature for at least three consecutive mornings (women who are menstruating should either take their temperature when on the second, third or fourth day of their period. If you have passed the menopause you can take your temperature on any day.)
  • Normal temperature readings are between 36.6 and 36.8 degrees Celsius
  • If your temperature falls below this you may have an underactive thyroid
  • If your temperature is above this you may have an overactive thyroid

Nutritional recommendations for thyroid problems

  • Avoid caffeine, reduce stimulants, such as tea, coffee, alcohol and chocolate as these overwork the endocrine system, the increase in stress hormones from the adrenal glands will slow down thyroid function.
  • If you have an overactive thryoid consume goitrogens e.g, turnips, broccoli, cauliflower, Brussels sprouts, kale, watercress, swede, cabbage, mustard, peanut, walnuts, millet, soya beans. But do not eat in excess. Goitrogens reduce iodine take-up by the thyroid. If you have an underactive thyroid, eat these foods in moderation, and lightly cook them before eating as cooking inactivates the goitrogens.
  • Include tyrosine rich foods in your diet, such as fish, butter beans, bananas, almonds, avocados and pumpkin seeds
  • Increase iodine intake. Iodine is found in oysters, sardines, iodised salt, seaweed (for example kelp, nori and arame) mushrooms, swiss chard, butter beans, pumpkin seeds, sesame seeds, egg yolk, lecithin artichokes. Onion and garlic. Iodine can also be supplemented but do not exceed 600 mcg a day. If consumed in excess, iodine can actually cause an underactive thyroid
  • Eat selenium rich foods. Best sources include: tuna, herring, cottage cheese, mushrooms, cod and chicken.
  • Reduce refined carbohydrates, such as sugar, white bread, white pasta, white rice, and replace with their brown or wholegrain counterparts. (Wholegrain bread, brown rice, whole-wheat pasta) Refined products unbalance the hormonal system, effecting blood glucose, adrenal hormones, sex hormones and thyroid hormones.
  • Include a source of protein with each meal or snack. This will help balance your blood sugar and therefore stabilise your hormones. Good protein sources include, organic eggs, chicken, fish, and pulses such as lentils, chickpeas and mung beans.
  • Increase the amount of essential fats that you eat. These fats aid weight loss as they increase your metabolism. Good sources are, oily fish, avocados, nuts and seeds. Flax seeds are good as it contains a good balance of omega 3 to 6.
  • Drink filtered or bottled water wherever possible.
  • The trace mineral manganese is important in thyroid function so increase pecans, brazil nuts, almonds, rye, barley and buckwheat.
  • Use coconut oil when cooking as it stimulates the thyroid.
  • Eliminate any infections, which can attack the thyroid.
  • Carry out a liver detox to help eliminate chemicals and waste products from manufacturing processes.
  • Ensure you don’t have excess levels of heavy metals (this can be done through hair mineral analysis).
  • Food allergies and intolerances should be investigated as these can affect thyroid function
  • Take a multimineral and vitamin supplement which includes zinc, selenium, vitamin E, C and A and B vitamins as these are all required for healthy thyroid function, or take a separate B vitamin complex

Helpful hints

  • Consider coming off the pill or HRT as this can affect thyroid function
  • Stop smoking. Smoking is known to make an underactive thyroid worse.
  • Check adrenal gland function (since the thyroid is regulated by the adrenal gland).
  • Avoid stress, The stress hormone cortisol is known to hinder conversion of T4 to T3.
  • Support digestion. Tyrosine is obtained from protein. Protein can be difficult to digest. Chew food well, ensure you have enough HCL and digestive enzymes.
  • Exercise - exercise is important to stimulate thyroid function.
  • Avoid fluoride (in toothpastes) and chlorine (in tap water) as theses are chemically similar to iodine and can block iodine receptors in the thyroid.

If your thyroid is overactive

  •  Reduce or avoid stress
  • Ensure you get enough sleep
  • Eliminate foods, which contain iodine (oysters, sardines, iodised salt, kelp)
  • Eat small and frequent meals to ensure you maintain energy levels.

Other possible problems of the thyroid

Enlargement of the thyroid gland can result in large swollen mass. They are often removed because of their unsightly appearance or because they press against vital structures within the neck causing breathing and swallowing difficulties. Causes may include a diet deficient in iodine although this is rare with modern diets where iodine is present in many foods. A more likely cause would be an increase in TSH in response to a defect in normal hormone synthesis within the thyroid gland. The TSH comes from the pituitary and causes the thyroid gland to enlarge. This process takes several years.

A relatively common occurrence, but one with good prognosis for recovery. Symptoms may include hoarseness, neck pain and enlargement of lymph nodes. Usual treatment is with radioactive iodine, which is an extremely safe treatment.

Usually benign growths but some may become malignant. Most people will have at least one nodule of this abnormal tissue and mostly be unaware of their existence. Most are benign.

This is inflammation of the thyroid gland. Causes are varied.

This article has
been written by
Terry Fairclough