Thyroid health and autoimmunity

Why is thyroid health important?

The thyroid is involved in numerous vital functions in the body. Its main role is to control metabolism. It impacts on growth and development, heart, muscle and brain health, as well as digestive function and and bone health. So it is hugely influential.

Low thyroid function is very common, particularly in women. According to government statistics, in the UK it affects 15 in every 1,000 women, and 1 in every 1,000 men. Yet we also know that thyroid problems are heavily underdiganosed, so true numbers may be higher.

The most common cause for low thyroid function is the autoimmune condition Hashimoto’s, where the body attacks its own thyroid tissue. People who already have a separate autoimmune condition have an increased risk of developing Hashimoto’s. Hashimoto’s is particularly common in those with rheumatoid arthritis, autoimmune alopecia and coeliacs. Women going through peri-menopause and menopause are also at increased risk of developing low thyroid function.

It is important to remember that the thyroid can also be overactive (Grave’s disease is the autoimmune disease where the thyroid is overactive), but we are only talking about low thyroid function here, which is much more common.

What are the signs that my thyroid function may be low?

Common signs that your thyroid function may be low include fatigue, depression / low mood, slow thoughts, feeling cold most of the time, muscle aches and cramps, constipation, weight gain, thinning hair and dry skin.

You may have noticed this list of symptoms above all describe ‘slowness’ in the body. When thyroid function is low, it slows down many processes in the body. This is because the thyroid produces hormones that control metabolic rate and growth and development. When thyroid production slows, these processes also slow down.

Research shows that many people with signs of depression, who are put on anti-depressants, may actually be suffering from low thyroid function. If you have depression, it is always worth considering whether low thyroid function may be contributing to your symptoms.

People with signs of poor blood sugar balance should also consider whether this may be due to low thyroid function. Blood sugar dysregulation symptoms include irritability or anxiety, fatigue (especially mid afternoon), headaches, shakiness, and blurred vision, as well as cravings for sugary foods and refined carbohydrates.

Low thyroid function can drive poor blood sugar balance since when our thyroid function is low, the body thinks we need more glucose, as glucose is required for thyroid production. This leads to blood sugar dysregulation, which means that sugars from our food are released too quickly into our blood, leading to peaks and troughs of energy and insulin. This causes inflammation, which can drive autoimmunity.

Furthermore, when our blood sugars are peaking and troughing, our behaviour tends to become more erratic and sugar cravings increase. So we can start to take on dietary and lifestyle habits that promote further inflammation (more junk food, poor sleep, higher stress, less exercise) and increase the risk of autoimmune flares. So low thyroid function, blood sugar dysregulation and autoimmune flares can often occur together.

Testing

Thyroid testing can be problematic. Testing within our healthcare system is based on cut off points, rather than letting us know where we stand on the spectrum. Cut off points are set according to where that healthcare scheme can helpfully intervene, rather than where sub optimal function may be contributing to symptoms. It is worth noting that cut off points for thyroid vary greatly across different countries. The language around thyroid testing is often misleading. When we are told our thyroid function is fine, in some cases this can actually mean that our thyroid function is not optimal and may be contributing to our symptoms, but it is not (yet) bad enough that medication can be justified.

Cut off points are based on a typical individual, yet very few of us are typical in reality, and what may be a normal thyroid level for one person, will not be normal for somebody else. This appears to be particularly true for the thyroid. This is why looking at symptoms in conjunction with test results is so important.

Most people will find that their doctor will only test their TSH level, due to cost implications. Unfortunately TSH only reflects the combined amount of T4 and T3. The main active thyroid hormone is T3, although T4 is mildly active. The body is able to convert T4 to T3 in theory. Where the body is able to manage this conversion well, TSH is a fairly good reflection of the body’s ability to produce sufficient active T3 overall. However, particularly in those with autoimmune conditions, some people cannot convert T4 to T3 efficiently. In these cases, their TSH reading may be fine, because they have a good combined level of T4 and T3. However, they are not converting T4 to T3 easily, meaning that their main active thyroid hormone, T3, is low, yet this is not picked up on the TSH test.

This is why it is important to run a more comprehensive thyroid panel, that looks at T4 and T3 as well. These panels start from around £95, with costs depending on how extensively the various forms of these hormones and their take-up by the body are analysed.

These more comprehensive panels will also include autoimmune antibodies for Hashimoto’s (autoimmune hypothyroidism). If someone has an underactive thyroid, it is important to find out whether it has an autoimmune component to it, as this will determine what type of support they should receive.

What can I do about it?

The thyroid can be very responsive to diet and lifestyle changes. This can be both positive and negative, since in times of stress and poor diet, the thyroid can be significantly affected. Yet equally it is possible to hugely influence the thyroid through positive dietary and lifestyle changes too.

Stress

Thyroid production is extremely sensitive to stress, or more specifically to cortisol, the ‘fight or flight’ hormone. Excessive cortisol in the system over an extended period, otherwise known as chronic stress, is usually a significant part of the picture for people with low thyroid function, as it inhibits thyroid production. When we take a case history for people with low thyroid function and we look back to the months preceding low thyroid symptoms, we usually find high levels of stress.

We can help to lower cortisol levels in the body by creating a more nurturing routine, making sure that meals are regular and are designed to balance blood sugar levels (troughing blood sugar levels are very stressful for the body and can also impact sleep quality), making sure the body has all the nutrients it needs, creating movement routines that help the body to feel safe, designing meals that are comforting and bring pleasure, as well as focusing on building in regular activities and connections with people that help that person to feel safe and happy.

T4 to T3 conversion

Poor T4 to T3 conversion tends to lie at the heart of the problem for many people with symptoms of low thyroid. This is due to the fact that 60% of the conversion takes place in the liver, while 20% takes place in the gut (with the remainder taking place in the heart, muscle and nerves). Not only is liver and gut health declining in our general population, due to increasingly toxic diets and lifestyles, but it is particularly affected in autoimmunity. Poor gut and liver health are associated with autoimmunity. We know that around 70% of our immune system is located in our guts and that gut function tends to be significantly affected in autoimmunity. When the body is inflamed, the liver struggles under the increased toxic burden and this can significantly inhibit T4 to T3 conversion too.

Yet this can be viewed as an opportunity, because when we work on our gut and liver health, we often see an improvement in this conversion rate, and consequently a reduction in low thyroid symptoms, as well as improvements in our autoimmune conditions more widely.

Gut and liver health are huge topics, too large to go into in any depth here, not least because each person’s case is different. In general, gut health can be supported by temporarily avoiding foods we are intolerant too, as well as ultra processed foods that damage the gut lining, while building up microbiome health, supporting the gut barrier function and optimising nutrient levels. Liver health can be supported by reducing the burdens on the liver. Dysregulated blood sugar levels leading to high insulin is one of the largest burdens, so working in this area can actually improve thyroid conversion (see How Balancing Your Blood Sugar Can Help Your Autoimmune Condition and How Certain Lifestyle Factors Can Be Driving your Blood Sugar Dysregulation). High histamine levels are also a huge burden on the liver (see Histamine Case Study). Dysregulated reproductive hormones also disrupt liver function (see Oestrogen, Progesterone and Autoimmunity). Reducing every day toxins, such as plastics and heavy metals, alcohol, sugar, man made chemicals, as well as reducing substances like caffiene, which also burden these pathways, can help.

Optimising nutrients that are required for the liver detoxification pathways to work optimally can also be very supportive. Testing and taking a detailed case history can help to pinpoint which liver pathways are struggling and which nutrients are low. Working on the liver at this deeper level can be really rewarding. This is best done with the help of a registered nutritionist. We often find that certain nutrients, such as B6, B12, B3, magnesium and vitamin C are low. Sometimes additional nutrients such as choline are low too. Some people, particularly women, may find that their protein intake is a little low, which can also disrupt these detoxification pathways, as well as negatively impacting blood sugar balance.

Lastly, cortisol can impede these detoxification pathways, again providing another reason why stress is so strongly linked with low thyroid production, as well as liver health, inflammation and autoimmunity more widely.

Specific Nutrients

Iodine

There are certain specific nutrients that the body needs in order to make thyroid hormones. Iodine is perhaps best known for supporting thyroid function. However, in reality iodine deficiency is very rare and supplementation can lead to dangerously high levels of iodine, so great care must be taken around this nutrient. If iodine deficiency is suspected, iodine levels should be tested and guidance should be sought from a registered nutritionist.

Selenium

Selenium is required to convert T4 to T3, however since the body prioritises thyroid conversion over other non-thyroid related functions that also require selenium, low selenium levels are unlikely to affect the thyroid, unless they are extremely low. As with iodine, high selenium is extremely toxic, so any supplementation should be done under registered nutritionist guidance and testing. It can be tempting to rely on Brazil nuts for selenium, yet these can often be high in barium, which is toxic, so it is best to take a considered approach and seek professional advice.

Iron

Iron tends to be the most relevant nutrient to consider for those with low thyroid function, especially women, since women are more likely to have iron-related anaemia. Iron supplementation is also problematic though. It can upset digestive function, leading to a cascade of further problems. It can also impede thyroid medication absorption, for those already taking thyroid medication. Iron should be taken at least four hours away from thyroid medication. Often iron deficiency is best resolved by looking at what may be causing it, rather than simply adding a supplement. Sometimes the issue is not that we are not consuming enough iron, but rather that the iron is not being absorbed. Good stomach acid levels are required for iron absorption. Yet stress significantly reduces stomach acid, again yet another link between stress and thyroid production.

Iron absorption is also affected by the levels of other minerals in our body, particularly zinc. There is good evidence to show that optimising zinc levels can support iron levels. Zinc supplementation can upset digestion, so it is best to work with a registered nutritionist to find a way of increasing zinc levels through diet, and possibly through supplementation too, that works best for you.

Cruciferous vegetables

While some research suggests cruciferous vegetables may negatively impact thyroid levels, more in-depth research appears to show that cooking cruciferous vegetables cancels out this effect. Cruciferous vegetables are extremely important for our overall health, not least due to their high sulphur content, which supports the sulphation detoxification pathway in the liver. It is really important to maintain as wide an intake of plant foods as possible, since over time reducing plant food variety tends to lead to a deterioration in microbiome health, which is so important for immune, digestive, and blood sugar function.

Soy

Research around soy and thyroid health can be confusing. The best quality evidence appears to show that consuming whole soy foods, such as tofu and edamame beans, is beneficial for health. However, foods containing soy should not be taken within three hours of thyroid medication, as it may reduce absorption.

Gluten

Lastly, it is worth noting that coeliac disease in adults is associated with autoimmune thyroid conditions. This may be due to similarities in the chemical make-up of gluten and thyroid, which means that if the body is reacting to one of these, it is more likely to also react to the other. There is some evidence to show that a gluten-free diet may help those with autoimmune low thyroid function. If you are considering going gluten-free, it is best to seek professional help to make sure that you avoid the common pitfalls, particularly around avoiding ultra processed gluten-free foods, avoiding all oats if possible, and understanding which grains you can eat, as well as ensuring you are not narrowing the variety in your diet overall, which can be achieved by adding in additional foods that you were not eating before.

Medication

Thyroid medication can be extremely helpful in reducing symptoms. It is important to remember to avoid foods high in iron, calcium (especially dairy) within four hours and soy within three hours of taking thyroid medication, as this may inhibit absorption of the medication.

Thyroid medication is essentially a synthetic version of the T4 hormone. Therefore, for it be effective, we still need our bodies to convert it into the main active thyroid hormone T3, as T4 is only mildly active. So it is really important to work on those factors set out above which support this conversion (ie gut and liver health). Taking the medication alone may not be enough for those people who still have poor T4 to T3 conversion.

For people taking thyroid medication, whose symptoms do not improve, it is worth considering a more in-depth thyroid testing panel which can look at how well this conversion is taking place. TSH alone may be misleading, since as long as you are absorbing your thyroid medication (T4), your TSH reading is likely to be normal, even when you have low T3 due to poor conversion.

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