Do you feel exhausted, cold or mentally foggy? Perhaps your hair is thinning, your digestion has slowed or your weight is changing despite your efforts.
Thyroid function may be part of the picture, but understanding it involves more than recognising a list of symptoms.
I consider hormone production, conversion and availability, alongside the wider factors that may be affecting your health.
What does your thyroid do?
Your thyroid produces hormones that help regulate energy use, temperature, digestion, heart function and many other processes.
It produces mainly T4, also called thyroxine. Your body converts some T4 into T3, the more active thyroid hormone.
This conversion takes place in several tissues, including the liver and kidneys. It depends on functioning enzymes and appropriate nutritional support.
Your body also converts some T4 into reverse T3, an inactive metabolite. These pathways help regulate thyroid hormone activity.
Symptoms worth exploring
An underactive thyroid, or hypothyroidism, may be associated with:
- Fatigue and reduced stamina.
- Brain fog and poor concentration.
- Weight gain.
- Cold hands, feet or general cold intolerance.
- Lower body temperature.
- Thinning hair and dry skin.
- Constipation.
- Low mood or depression.
Anxiety can also occur alongside thyroid concerns, although it has many possible causes and can be a feature of an overactive thyroid too.
Symptoms guide the investigation, but they cannot establish a thyroid diagnosis on their own.
What can influence thyroid function?
Chronic stress
Prolonged stress can affect the hormonal signals involved in thyroid regulation.
Higher cortisol exposure can influence the conversion of T4 into T3. Illness, inflammation and inadequate food intake can also change conversion patterns, sometimes resulting in lower T3 and higher reverse T3.
This is why I consider sleep, recovery, food intake and physical demands alongside emotional stress.
Liver health
The liver participates in thyroid hormone conversion, processing and transport.
Liver dysfunction may alter these processes and the proteins that carry thyroid hormones in the blood.
Supporting liver and metabolic health may therefore be relevant when exploring thyroid symptoms. However, a raised reverse T3 result does not, by itself, diagnose a liver problem.
Oestrogen and hormone transport
Oestrogen can increase thyroid binding globulin, a protein that carries thyroid hormones in the bloodstream.
This can change total thyroid hormone measurements and, in some circumstances, influence treatment requirements.
The important issue is hormone transport and availability. It is not simply that excess oestrogen directly blocks thyroid hormone receptors.
Environmental exposures
Some environmental chemicals can interfere with thyroid processes. Exposure history may therefore be relevant, particularly where there is a specific occupational or environmental concern.
Halogens discussed in this context include fluorine, chlorine and bromine, more commonly encountered in compounds such as fluoride, chloride and bromide.
Their effects depend on the particular compound, amount and iodine status. Being a halogen does not automatically make a substance a thyroid disruptor.
Certain heavy metals can also affect thyroid biology at sufficient exposure levels. I consider credible exposure history rather than assuming that everyone with thyroid symptoms has metal toxicity.
Nutrients involved in hormone production
Iodine and tyrosine are building materials for thyroid hormones.
Iron supports the enzyme involved in hormone production.
Zinc, vitamin B2 and vitamin B3 contribute to the wider enzyme and energy systems that support normal thyroid function.
The aim is to establish whether nutritional needs are being met, rather than assume that everyone needs a combination of supplements.
Minerals and thyroid hormone metabolism
Selenium is particularly important for the enzymes that activate and inactivate thyroid hormones.
Zinc, iron, magnesium and adequate iodine also contribute to normal thyroid function and the metabolic processes around it.
Deficiencies can interfere with different parts of this system, but each nutrient has a different role. More is not automatically better.
What about Brazil nuts?
Brazil nuts can contribute selenium to the diet. One fresh Brazil nut a day, provided it has not become rancid, may be a food option for some people.
It should not be treated as a precise dose or automatically combined with a selenium supplement.
Why iodine needs particular care
Iodine is essential, but taking it without understanding your thyroid status can create problems.
Excessive iodine may aggravate thyroid dysfunction, particularly in susceptible people or those with autoimmune thyroid disease.
I would not recommend starting iodine simply because you feel cold, tired or notice thinning hair. Its use needs assessment and monitoring.
Your diet, existing supplements, thyroid results, antibodies and medical history all need to be considered first.
Which blood markers may be useful?
Depending on your circumstances, I may recommend reviewing:
TSH
The hormone released by the pituitary gland that signals the thyroid to produce hormones.
Total T4
A measurement of circulating thyroxine, including hormone attached to transport proteins.
Total T3
A measurement of circulating T3, also including the portion attached to proteins.
Reverse T3, where accessible and clinically relevant
An inactive thyroid hormone metabolite that may change during illness or other physiological stress. It does not diagnose a conversion disorder on its own and is not necessary for every assessment.
Thyroid antibodies
These may help identify autoimmune thyroid conditions when appropriate.
Free T4 or free T3 may also be relevant. Total hormone results can be affected by binding proteins, medicines and oestrogen exposure, so the choice of tests and their interpretation need context.
My approach
I bring together your symptoms, diagnosis, existing treatment, menstrual history, digestion, nutrition, sleep, stress and previous results.
Where appropriate, I may recommend further thyroid testing alongside iron studies, relevant nutritional markers and liver results.
Support may involve improving nutritional intake, addressing digestive difficulties, reviewing supplements and supporting recovery alongside prescribed care.
The aim is to understand what is affecting your thyroid health and build a plan that reflects your individual needs.
If you feel you need support in this area, please reach out and let’s take the next steps together towards improving your overall wellbeing.
Lisa Cahill
Qualified nurse and naturopathic nutritionist
Evolve Female Wellness
lisa@evolvefemalewellness.com
Any foods or supplements mentioned are included for information only and are not individual recommendations. They do not suit everybody. Iodine, selenium and other supplements require assessment of your needs, thyroid condition and medicines. Do not change prescribed thyroid medication without your prescriber.