Are you struggling to lose weight despite cutting back on portion sizes, snacks or carbs? Are you low in mood, experience ongoing fatigue and find it difficult to concentrate? Don’t assume this is due to getting older – it may be your thyroid needs some attention.
Thyroid imbalances are one of the most common conditions I see in clinic. Research suggests that one woman in eight will develop a thyroid disorder during her lifetime. And by the time they reach age 60, more than 20 percent will have a thyroid disorder. When’s the last time your GP tested your thyroid function?
Thyroid function affects every cell in the body. It is the main regulator of metabolism. If your thyroid gland is not producing optimally, your cells cannot properly take in the nutrients they need, receive the right amount of oxygen, or get rid of waste materials efficiently. Thyroid hormones also affect your heart, muscles, bones, and cholesterol.
Here are the common signs and symptoms of hypothyroidism
Fatigue, especially on waking
Morning stiffness, Raynaud’s-type symptoms
Slow cognition, poor memory
Sluggish bowels, constipation
Cold hands and feet
Low sex drive
Loss of the outer third of the eyebrows
Low heart rate and basal body temperature
There are two main hormones produced by the thyroid:
Triiodothyronine, known as T3
Tetraiodothyronine, known as T4
Thyroid cells combine iodine and the amino acid tyrosine to make T3 and T4. You may also have heard of Thyroid Stimulating Hormone (TSH). This is often the only marker tested by the GP for thyroid function assessment. TSH is produced by the pituitary gland in the brain and effectively tells the thyroid how much thyroid hormone to produce. Hypothyroidism occurs when the thyroid is not producing enough of its hormones. Hashimoto’s disease is an autoimmune thyroid condition and antibodies are produced to thyroid tissue. This causes the immune system to attack and destroy the thyroid, which over time causes a decline in thyroid hormone levels. Hashimoto’s disease is linked to other autoimmune conditions particularly Coeliac disease.
Abnormal blood levels of TSH, T4, T3, rT3 and the T3:rT3 ratio together with the presence of thyroid antibodies are used in Functional Nutrition testing to determine the true function of your thyroid. It is important to remember that the laboratory reference ranges for thyroid hormones are wide and that what may be an optimal level for one individual may not be enough to produce homeostasis in another.
If you suffer with a range of the symptoms above then get a full thyroid screen. Just because TSH is classed as within normal range does not mean there is nothing wrong with your thyroid.
The thyroid gland needs iodine and the amino acid L-tyrosine to make T4 and T3. A diet deficient in iodine can limit how much T4 the thyroid gland can produce and lead to hypothyroidism. T3 is the biologically active form of thyroid hormone. The majority of T3 is produced in the peripheral tissues by conversion of T4 to T3 by a selenium-dependent enzyme. Various factors including nutrient deficiencies, drugs, and chemical toxicity may interfere with conversion of T4 to T3
Another related enzyme converts T4 to an inactive form of T3 called reverse T3 (rT3). Reverse T3 does not have thyroid hormone activity; instead it blocks the thyroid hormone receptors in the cell hindering action of regular T3.
Pregnant women are especially at risk for hypothyroidism. During pregnancy, the thyroid gland produces more thyroid hormone than when a woman is not pregnant, and the gland may increase in size slightly. Uncorrected thyroid dysfunction during pregnancy can lead to preterm birth, mental retardation, and may increase the risk of miscarriage.
There can be a number of reasons why your thyroid function may be suboptimal – this includes stress, toxins, insufficient levels of key vitamins and minerals (e.g zinc, selenium, iodine, iron, copper, Vitamin E, vitamin D and B12), protein, infection and inflammation. Supplementation may be beneficial in optimising function together with lifestyle changes especially if stress is a factor.
Some foods contain goitrogenic substances that reduce the utilization of iodine. These foods include vegetables from the Brassica family (eg, cabbage, Brussels sprouts, and millet). However cooking significantly reduces the impact of these goitrogens on thyroid function and they are only considered a problem if you also are iodine deficient.
There is also a concern that isoflavone molecules in soy inhibit an enzyme involved in thyroid hormone synthesis. However if iodine is adequate it is unlikely to be an issue but I would still not recommend supplementation with soy or heavy soy consumption with a hypothyroid condition.
Don’t skimp on protein either – the amino acid L Tyrosine is essential for thyroid function so aim to include protein rich foods at each meal (eggs, meat, fish, poultry etc)