Iron deficiency is one of the most common issues athletes face. The effects of exercise on the thyroid gland and subsequent interplay between hormones, often goes unrecognised. Our Sports Naturopath and Nutritionist Kate Smyth explains the link between iron, exercise, hormones and thyroid function.
Thyroid Function and Iron Deficiency
Undiagnosed iron deficiency presents an increased risk of impaired thyroid function. Active women have high-energy lives, managing work, family and training, and many will accept low energy and brain fog as simply a result of being over-worked or as an inevitable part of hormonal changes.
However, low thyroid function, iron deficiency, over training and hormonal changes also present with many of the same symptoms.
Signs that your thyroid function may be underactive (hypothyroid) include fatigue, unexplained weight gain, headaches, low blood pressure, dry skin, constipation and cold intolerance. These early signs of cellular hypothyroidism can appear when blood pathology remains within standard ranges.
As with most chronic issues, there are multiple factors that may contribute to dysfunction.
The Link between Exercise and Thyroid Function
In athletes, endurance and high-volume training promotes thyroid function. During exercise, your hypothalamus stimulates the pituitary gland to secrete thyroid stimulating hormone (TSH), which in turn signals your thyroid to synthesise and release the thyroid storage hormone T4 and active thyroid hormone T3.
These hormones influence your body’s metabolism and allow it to increase exercise intensity (2). Over time, this repeated, high demand of your thyroid during prolonged intense exercise may impact your thyroid function, causing it to slow down and consequently lose the ability to produce sufficient hormones.
Iron Deficiency and other Key Nutrients for Thyroid Function
Normal thyroid function is dependent on several nutrients to regulate the synthesis of thyroid hormones. Iodine, iron, , tyrosine, selenium and zinc are needed to facilitate the conversion of T4 to T3 (1). A deficiency of any one of these nutrients would result in reduced T3 production, causing you to experience hypothyroid symptoms. Vitamin A and D also play important roles in cell receptor behaviour to regulate thyroid hormone metabolism.
While iodine is the key mineral for healthy thyroid function (read more…here) it is not uncommon to find iron deficiency in hypothyroidism (4).
Although widely recognized for its influence on red blood cell production, iron is also an important component of thyroid peroxidase, an enzyme essential for thyroid hormone biosynthesis.
Iron deficiency interferes with the normal functioning of the thyroid, contributing significantly to fatigue, exercise intolerance and light headedness.
Increased menstrual bleeding can lead to iron deficiency (6). Many of us dismiss low energy as a symptom of a busy, active lifestyle and so iron deficiency frequently goes undiagnosed in perimenopausal women. For athletes, iron plays a critical role in exercise performance as outlined in our blog “Increase your iron absorption and rebound from anaemia” here
The most common causes of iron deficiency include inadequate dietary iron intake, inflammation, poor iron absorption in the gut, parasites, iron loss through sweat, urination and faeces and blood loss through menstruation. Pregnancy, breastfeeding or high volume exercise will also significantly increase iron demands (5).
Thyroid Function and Sex Hormones in Women
Your thyroid function is sensitive to fluctuations in sex hormone levels, particularly oestrogen. Oestrogen stimulates the production of the thyroid hormone precursor, thyroglobulin, and increases the protein that carries thyroid hormones in your blood (3).
As oestrogen changes ( such as during peri-menopause) so too does thyroid hormones, which play an important role in metabolism, muscle strength, energy production and expenditure, heart function, and temperature regulation.
As oestrogen levels rise and fall later in life, menstruation may become irregular and heavier. Peri-menopausal women may experience symptoms for over ten years as described in our blog on “Natural solutions for menopause” here
During peri-menopause declining oestrogen may impact thyroid function and can lead to inadequate production and circulation of thyroid hormones.
Exercise During Hormonal Changes
Despite common misconceptions, women can train and perform well throughout peri-menopause, and beyond, if they listen to their body and be mindful of maintaining adequate dietary intake of key nutrients. It is important to recognise that both iron deficiency, thyroid function and hormonal changes can impact on your ability to exercise.
Years of consistent exercise accumulates like pages in a book. As a mature you know your body very well. The pathway to success utilises your book of wisdom and skills. Mature athletes can benefit from greater recovery, individualized strength and conditioning and modified programs. Focussing on the balance between training intensity and volume will help you to achieve your desired goals.
If you suspect your symptoms are impacting on your quality of life and sport, it’s time to seek support to help you navigate the journey.
Blood serum pathology and functional tissue mineral testing can be a good starting to point due to the critical role nutrients play in hormonal and thyroid function.
With the right self-care and a holistic approach to health, you can continue to achieve your life goals and physical challenges irrespective of hormonal changes. For further information contact our Sports Naturopath Kate Smyth for an individual assessment here
As an evidence-based practitioner, Kate pride’s herself in helping patients develop a deeper understanding of their body. If you would like to do further reading, you may like to explore some of the key references included in this blog below.
- Kawicka, A., & Regulska-Ilow, B. (2015). Metabolic disorders and nutritional status in autoimmune thyroid diseases. Postepy Higieny i Medycyny Doswiadczalnej, 69, 80–90.
- Luksch, J. R., & Collins, P. B. (2018). Thyroid Disorders in Athletes. Current Sports Medicine Reports, 17(2), 59–64.
- Santin, A. P., & Furlanetto, T. W. (2011). Role of estrogen in thyroid function and growth regulation. Journal of Thyroid Research, 2011.
- Soliman, A. T., De Sanctis, V., Yassin, M., Wagdy, M., & Soliman, N. (2017). Chronic anemia and thyroid function. Acta Biomedica, 88(1), 119–127.
- Wouthuyzen-Bakker, M., & Van Assen, S. (2015). Exercise-induced anaemia: A forgotten cause of iron deficiency anaemia in young adults. British Journal of General Practice, 65(634), 268–269.