Nourish your thyroid for better performance

You will rarely find the thyroid gland discussed within sports nutrition circles, but it absolutely should be… Not only are thyroid issues absolutely accepted as ‘real’ within sports medicine and exercise endocrinology, but we choose to nourish our thyroid gland via the foods we eat and supplements we take, plus our thyroid gland is heavily affected by our training and lifestyle load/stress.

As I noted in my FSN full thyroid article a few years ago, there have been some pretty high profile athletes ‘diagnosed’ with hypothyroidism, including London Olympic 10,000m silver medalist Galen Rupp. As I discussed in this article, it is fair to say that if you push your training and stress-oriented lifestyle strongly enough for long enough, sooner or later, your T4 (thyroxine) levels will fall below a laboratory reference range. In elite sport, there is obviously a controversial advantage to being placed on thyroid medication, which is physiologically known to stimulate metabolism and to significantly bolster energy.

However, there is a downside to most medications. In this case, by exogenously supporting your thyroid gland, you may actually be weakening the output of your own thyroid gland, plus displacing the stress of your training and lifestyle onto other endocrine systems. Most notably; adrenal fatigue, compromised testosterone and DHEA levels, and disturbed oestrogen-progesterone rhythms and natural clearance may result from ‘pushing on’ with some pharmaceutical assistance - all of these are common occurrences for serious elite or recreational athletes.

However, not all of us are elite athletes looking for an edge, so what about a more gentle approach to supporting our thyroid gland and metabolic fire? Let’s now turn to a bit of nutrition… As you can see in the diagram below, thyroid hormones (T4 and T3) are made from the amino acid l-tyrosine. It is one of my favourite supplement choices in a burned out athlete, because it is a precursor nutrient for both thyroid and adrenal function - it’s gentle in its action, but most people can feel a difference in their energy. I usually suggest around 500 mg on waking and 500 mg prior to lunch on an empty stomach (for optimal amino acid absorption). Don’t take it later in the day because you don’t want to disrupt the natural cortisol curve, which should drop towards the latter part of the day.


As you can also see by the diagram, for conversion of l-tyrosine to T4, we need iodine, and for the conversion of T4 to T3, the most active thyroid hormone, we need selenium and zinc. Iodine is low in most athlete’s diets nowadays because we don’t eat much fish or seaweed. Zinc is a co-factor in many biochemical reactions, including the production of ATP (a pressurised system in athletes), and is a common deficiency in athletes. Selenium supports the innate antioxidant systems in our body, which is also pressurised with heavy training loads. So, athletes have an increased need for all of these nutrients compared to the average person. Sure, athletes generally eat a lot more food than average people, but with the standard over-focus on ‘macros’ in an athlete’s diet, a lot of that consumption is calorie-dense, but micronutrient poor.

Good foods sources of iodine are: sea vegetables, fish, dairy products and eggs.

Good sources of zinc are: meat, fish, seeds, nuts and legumes.

Good sources of selenium are: fish, meat and Brazil nuts. Selenium is also found in plants, but is highly dependent on the selenium content of the soil, and with the taste of the average vegetable being watery and lacking in minerals, and the current rise of veganism in sport, this is a concern.

In addition to focusing on micronutrient concentration in our foods and that of our athletes, it is reasonable to consider a thyroid support if there are signs of compromised thyroid function. Most of the best quality supplement ranges contain one that is specific to thyroid function. For example, the one I use with my clients contains vitamin A, vitamin D3, vitamin E, iodine, zinc, selenium, guggulsterones, rosemary extract, and ashwaganda (for adaptogenic support).

You’ll also notice from the diagram that pretty much any form of stress (including chronic heavy training) will inhibit the conversion of T4 to T3, meaning less metabolic function from the thyroid gland. But more than that; most types of stress will push T4 towards reverse T3, which directly inhibits T3 - a double whammy effect. So, in addition to making sure that your athlete is optimally nourished with good-quality foods and supplements that include the provision of the minerals iodine, zinc and selenium, we need to also become a life coach and a sports coach to them. If it is clear to you that your athlete’s lifestyle is compromising their thyroid output, or any other endocrine gland, as a practitioner it is absolutely your place to say so.

For a much more in-depth read of the importance of thyroid support for athletes, click here.