What is vitamin D?

Unlike other vitamins, your body can make its own vitamin D when the skin is exposed to the sun, stimulating production. The vitamin D is then converted to a hormone called Calcitrol (or activated vitamin D) and sent to cells and organs of the body where it’s needed.

Vitamin D promotes the absorption of calcium which is needed for healthy bones and teeth.

It is also required for:

  • Healthy heart and circulation
  • Protection from infection
  • Healthy lungs and airways
  • Muscle function
  • Brain development

A lack of vitamin D, or deficiency, can lead to brittle or soft bones (osteoporosis/osteomalacia).

There are numerous studies linking vitamin D to health, including:

  • Lowering blood pressure
  • Reduction of precancerous polyps of the colon
  • Improved heart function

How do I get more D?

Sun exposure is the most natural and cost effective way of increasing your vitamin D levels, however, due to the risks of sunburn and skin cancer, we are warned to limit our time in the sun. Your levels of vitamin D production using this method are also dependent on where you live. People living in areas where there are fewer sunny days per year, may not be able to produce enough vitamin D this way.

It is also important to consider how quickly you are likely to burn and how dark your skin is (darker skin would require more time in the sunlight in order to make vitamin D).

  • In the US, cow’s milk has been supplemented with vitamin D since the 1930’s at a level of 100IU per cup. Other foods fortified include yogurts, cereals and juice.
  • Vitamin D occurs naturally in oily fish and eggs.

The daily value of vitamin D is set at 400IU, with an upper limit of 4000IU.

There are arguments for the recommended levels to be increased and for more food to be fortified, but this is an ongoing debate.

Who is at risk from vitamin D deficiency?

  • Pregnant and breast feeding women
  • Babies and children (unless they are given a fortified milk on a daily basis)
  • Over 65’s tend to have lower levels and their bodies are less able to make vitamin D naturally via exposure to sunlight
  • Those not exposed to much sunlight, for example if they are housebound or they cover up the majority of their skin

If you consider yourself at risk from vitamin D deficiency, you should visit your general practitioner to discuss symptoms and possible supplementation.

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