In a nutshell:
• Thyroid health is complex and fascinating
• Many people have heard of thyroxine (T4) but few are aware that this must be converted into tri-iodothyronine (T3) in the body
• T3 is the most active form of thyroid hormone that the body can use
• In times of chronic stress, T4 may be converted to reverse T3; an inactive form of thyroid hormone that the body can’t use
• The conversion of thyroxine (T4) into tri-iodothyronine (T3) requires a range of essential micronutrients and takes place in the liver, other cells such as the heart, muscles and nerves and even healthy gut bacteria can help to convert T4 – T3
• Many factors can either hinder or support the conversion of T4 – T3
• Effective thyroid support involves thinking outside the box and supporting the healthy conversion of T4 – T3 via a multi-faceted approach
• The good news is that there are many simple dietary and lifestyle changes you can make to support optimal thyroid health. Read on to find out more.
Thinking outside the box
Thyroid health is complex and fascinating. The thyroid is a small, bow-tie-shaped gland located at the front of the throat. It is responsible for controlling the body’s metabolic rate; in fact, every cell in the body depends on thyroid hormones for regulation of metabolism.
Such widespread activity throughout the body means that the range of symptoms that can occur when thyroid function is below par are almost endless. Classic symptoms of hypothyroid are weight gain, feeling the cold, sluggishness, cold hands and feet, low energy and depression, but there are many more besides; from palpitations, high cholesterol, panic attacks and constipation to muscle and joint pain, dry skin, headaches, PMS and many more.
Unless you are presenting with the classic symptoms of hypothyroid, clinical evaluation can be a challenge and so testing is strongly recommended. As a first port of call, your GP will usually measure levels of Thyroid Stimulating Hormone (TSH) and Thyroxine (free T4). There are significant limitations with testing only these two markers however; read our interview with thyroid testing expert Kate Osborne to understand why and to find out more about comprehensive thyroid testing.
One of the major limitations with conventional testing is that it typically measures only thyroxine (free T4). The thyroid gland produces mostly thyroxine (T4) (about 94%) and a much smaller amount of tri-iodothyronine (T3) (about 6%). However, T3 is actually the most active form of thyroid hormone. The majority of T4 must then be converted into T3 so the body can use it.
The conversion of T4 – T3 is crucial for thyroid health and is often overlooked. This conversion takes place in the liver, in other cells in the body such as the heart, muscles and nerves, and also via the activity of healthy gut bacteria in the intestinal tract.
T4 – T3 conversion is neither guaranteed nor straightforward, and only about 60% of T4 is converted into active T3 that the body can use. Around 20% of T4 may even be converted to reverse T3 – an inactive form of T3 that the body can’t use. And it’s important to understand that levels of reverse T3 (inactive T3) can become too high during highly stressful times, such as trauma, surgery or severe chronic illness.
No doubt you’ll be starting to understand why you need to think outside the box when it comes to thyroid support and how seemingly unrelated factors such as chronic stress and an imbalanced gut microbiome can play havoc with thyroid function.
Key factors that may affect thyroid hormone conversion:
Key factors that may INHIBIT the conversion of T4 - T3:
Chronic stress – During highly stressful times, T4 may be converted to reverse T3, an inactive form of T3 that the body can’t use. Taking steps to reduce stress and support a balanced stress response is vital to encourage healthy thyroid hormone conversion.
Elevated oestrogen – There are many possible underlying reasons for elevated oestrogen, it is crucial however to support balance to enable the healthy conversion of thyroid hormones. Supporting optimal liver detoxification processes may help to support oestrogen balance and in turn support thyroid health.
Low levels of beneficial gut bacteria – Healthy gut bacteria are one of the pathways used by the body to convert T4 – T3; antibiotic use is therefore bad news for thyroid function as it wipes out both good and bad bacteria. You can support a healthy gut microbiome via diet, lifestyle and supplementation if needed.
Micronutrient deficiencies – A wide range of essential vitamins and minerals are required for the production and conversion of thyroid hormones. Deficiency of any of these can therefore affect these processes. A varied, wholefood diet, rich in natural, unprocessed food is a crucial foundation for thyroid health. Dietary supplementation may help to optimise intake.
Inflammation – Many people are suffering from chronic low grade inflammation on a daily basis. Bringing inflammation back into balance is crucial for supporting the conversion of T4 - T3.
Neurotransmitter deficiency - Low levels of neurotransmitters such as serotonin and dopamine may inhibit the conversion of T4 – T3. As much as 90% of serotonin may be produced in the gut; another good reason why supporting a healthy gut is vital for optimal thyroid function.
Immune dysfunction – Another whole article (or book!) could be written on the role of immune dysfunction in thyroid problems. To keep it simple here though, it’s important to understand that immune imbalances are a common underlying cause of poor thyroid health.
Key factors that may SUPPORT the conversion of T4 - T3:
Selenium – This mineral is a major cofactor for the enzyme which helps to convert T4 – T3. Research shows that lower selenium status is associated with lower T3 production.
Zinc & Copper have a vital role to play in thyroid function; low zinc has been shown to reduce the production of T3. Zinc may also help to reduce thyroid antibodies. Zinc and copper work together to support thyroid function.
Magnesium – This mighty mineral is involved in pretty much every system in the body and yet commonly lacking in a typical Western diet. Magnesium is crucial for a healthy balanced stress response and so provides vital underlying support for thyroid function.
B vitamins – B vitamins are vital co-factors for the production of thyroid hormones and have a wider positive impact on many of the factors that can inhibit thyroid function. They help to support energy production, a balanced stress response, liver detoxification, production of neurotransmitters such as serotonin and healthy clearance of hormones such as oestrogen.
Gum guggul is a natural resin extracted from the mukul myrhh tree. Research shows that this plant extract can help to support the healthy production of T3. In addition, gum guggul has been found to support healthy cholesterol and triglyceride levels.
Beneficial bacteria – Optimal levels of healthy gut bacteria are vital for thyroid hormone conversion. You can support healthy levels of beneficial bacteria through diet, lifestyle and supplementation.
Vitamin D – Often nicknamed the ‘sunshine’ vitamin because the skin makes vitamin D on contact with the sun’s rays; this nutrient is important for immune balance which in turn helps to support a healthy thyroid. Current estimates suggest that many people are low in vitamin D and supplementation is generally recommended, especially during autumn and winter months when sunlight exposure is limited.
Omega 3s – EPA & DHA are omega 3 fats found in nuts, seeds and oily fish. They have been shown to have anti-inflammatory activity and are often lacking in a typical Western diet. Omega 3s may help to bring inflammatory processes back into balance and support a healthy conversion of T4 – T3.
Relaxation – It is vital to incorporate regular relaxation into your weekly routine to calm the stress response and support optimal thyroid function. Mindfulness, breathing exercises, yoga, pilates, time spent in nature and gentle exercise are all effective ways to help your body to relax. Schedule relaxation into your daily routine to support thyroid health.
Reduce your toxic load – The liver is a primary site for conversion of T4 – T3; looking after your thyroid health therefore involves taking care of your liver. A great place to start is to take steps to reduce your overall toxic load. This takes pressure off your liver so it can perform the important job of converting thyroid hormones into their active forms. This infographic is a great place to start.
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