Runners World, Part of the Hearst UK Wellbeing Network

Vitamin D is a fat-soluble vitamin and hormone which is produced in the body from sunlight, and is necessary for a number of important biological functions in the body.

One of its key roles is increasing the intestines’ ability to absorb other nutrients, such as calcium, magnesium Levels below 30nmol/l are too low and might weaken your bones and affect your health.

Additionally, research has shown us that Vitamin D is also necessary in runners to support muscular recovery. There are also associations with improved mood, due to it increasing levels of serotonin, which improves mood but also plays an important role in appetite regulation.

What is the supplement creatine The Journal of Metabolic Research, in which 165 men were either given a Vitamin D supplement or placebo for a year, demonstrated that those given the vitamin had higher increases in testosterone production than the control group. Testosterone has a strong role in body composition, particularly in building lean muscle mass. So staying on top of your Vitamin D levels has a critical role in both optimal health and performance outcomes.

What causes Vitamin D deficiency?

Vitamin D deficiency occurs due to insufficient sunlight but also when our stores become depleted. While many of us will top up our levels during the summer months, if we don’t supplement during the winter, we may find that we drain our stores. Runners need Vitamin D for muscular recovery, which can contribute to insufficient intakes. Additionally, individuals with darker skin have a higher requirement of Vitamin D in the first place. This is often overlooked, so the maintenance dose of 2000iu a day throughout the winter months may not be enough. For many people with dark skin, it may be necessary to supplement all year round.

What are the symptoms of Vitamin D deficiency?

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Levels of 50nmol/l (nanomoles per litre) or above are adequate for most people for bone and overall health.
Similarly, if you fall in the range of 50-75nmol/l, a daily dose of 5000iu a day should be taken.
One of its key roles is increasing the intestines ability to absorb other nutrients, such as.

However, when working with runners and athletes who are physically very active, studies recommend that ideal levels should be above 75nmol/L, and ideally above 90nmol/L. This can be tested by your GP but also there are numerous fingerpick test kits available on the market, such as Forth Edge, Thriva and Medichecks.

One of the most noticeable signs of deficiency is fatigue, to the point that it can be extreme, as if you are walking through treacle. Similarly, poor recovery between training sessions and increased muscle soreness are all potential signs, as well as a drop in mood.

What are the best foods that are rich in Vitamin D?

Similarly, if you fall in the range of 50-75nmol/l, a daily dose of 5000iu a day should be taken oily fish and eggs being some of the limited sources. Vitamin D is one of the few nutrients that we really do need to supplement and even consuming foods fortified with Vitamin D are unlikely to help you meet your needs.

How much Vitamin D should I take per day?

How much Vitamin D we consume is dependent on our blood levels. For those of us who have sufficient levels, a maintenance dose of 2000iu a day is recommended, especially through the autumn and winter months, from September to April.

Updated: 27 November 2023.

For those of us who may show up as being deficient (that is, levels below 30nmol/l) a high dose protocol will be necessary, and this is best advised by your GP or a registered dietitian.

There are two types of Vitamin D: D2 is made from plants and is found in fortified foods and some supplements. Vitamin D3 is naturally produced in the human body and is found in animal foods.

A meta-analysis of controlled trials comparing the effects of D2 and D3 supplements on blood levels concluded that D3 supplements raised blood concentration levels more and also for a more sustained period of time.

As for which format is best, for example spray versus capsule, both showed improvements and generally it comes down to what is preferred and which option you can maintain regularly.