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Vitamin D - do I need a supplement?

Vitamin D plays a vital role in keeping out bones and muscles strong helping us to reach our full sporting potential. Living in the UK puts us at risk of being deficient; carry on reading to find out more.

Why is Vitamin D important?

Vitamin D helps us to absorb calcium and phosphorous from our diet, which are used to keep our bones strong. Vitamin D is also involved in skeletal muscle growth and plays a role in aerobic exercise and enabling us to reach our full capacity. Although studies have not conclusively shown that taking a Vitamin D supplement will lead to an improved exercise performance there is data to show that a deficiency in vitamin D could hamper performance.

Vitamin D also plays a role in our immune system as well as having anti-inflammatory properties, which are very important especially following a hard training session.

Where can we get Vitamin D from?

Vitamin D is available in small quantities in our diet from oily fish, red meat, liver, egg yolks and fortified foods. 90% of our vitamin D is made under our skin when we are exposed to sunlight. This only occurs between April and September in the UK with this window reducing the further North you are due to the angle of the sun.

UVB radiation from sunlight provides the energy needed for our bodies to make Vitamin D. Sun cream protects our skin from the damage that can be caused by UVB. When you are wearing sun cream you are not able to use UVB to make vitamin D. It is not advisable to reduce the amount of sun cream you apply due to the risk of skin cancer. People with darker skin are also at greater risk of deficiency as the pigmentation in the skin inhibits absorption of the UVB radiation.

Who should take a vitamin D supplement?

Almost everyone in the UK should consider taking a supplement during the winter months when we are unable to make it ourselves. A year round supplement may be of benefit to some especially those who spend very little time outdoors or a majority of that time their skin is covered by clothing or sun cream. If you have darker skin and especially if you live further North a year round supplement may be appropriate.

Vitamin D can be stored in our bodies, so some people are able to produce and store enough in the summer months to stop them becoming deficient in the winter. However, many studies have recorded high percentages of outdoor based athletes who are deficient in the winter months even with high levels of sun exposure in the summer.

Who shouldn’t take a vitamin D supplement?

High doses of vitamin D should be avoided if you have certain health conditions such as sarcoidosis, decreased kidney function, kidney stones or high amounts of phosphate, calcium or vitamin D in your blood. If you are unsure if you should take it then seek advice from your doctor or pharmacist.

How much should I take?

The recommendation for anyone aged over one year old is 10 micrograms per day, equivalent to 400IU per day. This is a safe dose and should meet most people’s needs; it should not be exceeded as this can cause a build-up of calcium within the body.

If you are unsure if you should start taking a vitamin D supplement please seek advice from your GP or Dietitian.

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