Vegetarian/vegan athlete – Vitamin D, iodine, vitamin B2 and coenzyme Q10

Vitamin D

Why is it important?

Vitamin D is a fat-soluble vitamin essential for a number of bodily functions. It plays a crucial role in the absorption of calcium and phosphorus, two important minerals for healthy bones and teeth.

It promotes healthy bone mineralization and reduces the risk of fractures. It helps defend against infection, reduces inflammation and regulates mood. Essential for sportswomen, it contributes to proper neuromuscular function and a diversified intestinal flora.

Provided mainly by oily fish (sardines, mackerel, anchovies) and eggs, vegetarians and vegans are at greater risk of vitamin D deficiency. The SU.VI.MAX study reports that 78% of women aged between 35 and 65 suffer from vitamin D deficiency, whatever their diet.

How can I increase my vitamin D status?

The main source is UV-B radiation and exposure to the sun. But this synthesis pathway depends on many factors:

• latitude: people living in the northern hemisphere are more at risk of deficiency because they are less exposed to sunlight
• the season: the sun’s rays are stronger in summer, enabling better synthesis. In winter, we use our summer reserves.
• the person’s age: the ability to synthesize vitamin D diminishes with age
• skin pigmentation: dark-skinned people are less able to synthesize vitamin D
• genetics: vitamin D absorption capacity varies greatly from one individual to another

As you can see, depending on your genetics, the environment in which you live and your diet (vegetarian, vegan or otherwise), you may be more or less exposed to vitamin D deficiency.

For good synthesis, therefore, spend at least 15 minutes outdoors in the late morning or afternoon (when wavelengths are most conducive to synthesis), between April and September.

Outside these periods (between September and April), our bodies are living on summer reserves, so we may need to supplement daily. The dose depends on your initial status, which can be checked by a blood test.

Iodine

Why is it important?

Iodine is a trace element essential for thyroid function and the synthesis of thyroid hormones (T4 and T3). These hormones act on many tissues: they speed up metabolism, increase heat production and enable the growth and development of nerve, muscle and bone tissue.

If the body lacks iodine, thyroid hormone secretion is reduced, which can lead to weight gain, fatigue and, in the longer term, hypothyroidism.

According to a report published in 2024 by the WHO,changing diets are increasing the risk of iodine deficiency. The report highlights the fact that we consume more vegetable substitutes than dairy products or marine fish, which are the main sources of iodine.

How can I increase my iodine status?

For vegetarians, I advise you to continue consuming dairy products on a daily basis (milk, yoghurt, cheese) or eggs , which provide a little iodine. For vegans, you can enrich your diet with seaweed and iodized salt.

Contact a healthcare professional to ask for an ioduria test to check your iodine status and, if necessary, start taking supplements.

Vitamin B2

Why is it important?

Vitamin B2 (riboflavin) is a water-soluble vitamin that is particularly important for athletes. Like all B vitamins, it is involved in energy metabolism. It helps convert carbohydrates, fats and proteins into energy, which is crucial for healthy cell function.

It also helps maintain healthy skin, as well as the mucous membranes of the eyes, mouth and digestive system.

The main sources are liver, dairy products and eggs, which is why vegans are more exposed to the risk of deficiency.

How can I increase my vitamin B2 status?

For vegetarians, you can eat cheeses (especially soft cheeses) or eggs that contain them.

For vegans, certain plant-based foods are rich in this vitamin, such as avocados, almonds and mushrooms (Shiitake). Note, however, that this vitamin is photosensitive, so these foods should be kept away from light.

Coenzyme Q10

Why is it important?

Coenzyme Q10 is a molecule naturally present in the human body, notably in the mitochondria, our cells’ little energy powerhouses. It plays an essential role in energy production , which is crucial for the proper functioning of cells and organs, especially when you’re an athlete.

In addition to its role in energy production, CoQ10 is also a powerful antioxidant, protecting cells against oxidative damage caused by free radicals. This can have a beneficial effect on heart health, reducing inflammation and preventing premature aging.

Coenzyme Q10 is mainly provided by animal products such as meat (beef, chicken) and fish. As a result, vegetarian or vegan diets can make it difficult to achieve optimal coenzyme Q10 levels, especially when you’re an athlete, a situation which increases your energy and antioxidant requirements.

How can I increase my coenzyme Q10 status?

I advise you to have your coenzyme Q10 status measured to find out what your levels are and whether you need supplementation. Bear in mind that the reliability of the measurement is not totally guaranteed, but rather provides an overall picture of your status.

Q10 can be supplemented in two forms: ubiquinone (less expensive) or ubiquinol, which is more expensive but better absorbed from the intestine.

Like marathon runners Shalane Flanagan (winner of the 2017 New York Marathon) and Desiree Linden (winner of the 2018 Boston Marathon), if you too have or want to opt for a predominantly plant-based diet, remember to optimize your intake of essential micronutrients!