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The importance of vitamin D for runners

It is widely known that consuming a colourful diet, rich in diversity and flavour, is the best way in which to meet our micronutrient needs and function at our optimum.

However, as the days get shorter and the trees start to change colour, there is one nutrient in particular that becomes difficult to obtain from our external environment.

Vitamin D can be synthesised by our skin when exposed to sunlight (around 30 minutes daily exposure to face, hands and arms without the protection of sun cream is thought to be adequate for the majority of people).

During the winter months in the UK, the levels of ultraviolet B radiation in sunlight are no longer sufficient for this process to take place, so it is a good idea to get it elsewhere.

Vitamin D can be found in some foods

Oily fish, such as salmon and mackerel, is a good source, but this is not eaten regularly by most people, let alone daily. Egg yolks are another, but one egg contains only approximately 5% of your daily vitamin D requirement. Some breakfast cereals may also be fortified in small amounts. How about some liver? Anyone?

It is very difficult to achieve a sufficient intake through food alone, with so few sources. This is why Public Health England and the NHS recommend that everyone takes a 10μg or 400IU supplement daily from the age of 1 between the months of October and April in the UK.

So why is vitamin D important?

Vitamin D is vital for bone health.

Our bones are constantly being both broken down and reformed in a process called remodelling.

During developmental years, bone density should be gradually increasing.

At age 30-35, we reach our individual peak bone mass, a figure largely determined by nutrition and activity levels during childhood and adolescence.

From this age onwards, bone density very gradually decreases as slightly more bone is lost than gained. This process can be slowed through exercise and diet.

Bones and teeth hold 99% of the body’s calcium. Calcium has important uses within the body, such as being a key player in muscle contraction and nerve impulses. If the body has insufficient calcium to carry out bodily functions, it will take from the reservoir we store in our bones. Therefore, adequate calcium intake is necessary to maintain as much bone density as possible as we age.

But where does vitamin D come in?

Vitamin D regulates calcium uptake by maximising the number of transporters and receptors in the gut lining, enabling the absorption of calcium from digested food into the blood stream.

So, adequate vitamin D is necessary to ensure we can uptake enough calcium (obviously dependant on adequate calcium in the diet).

Consequences of insufficient vitamin D