Vitamin D supplements: are they really worth taking?

The simple answer is yes! Many of my patients ask me whether or not they should be taking vitamin D supplements, or whether they should have their levels measured by a blood test.

Vitamin D is a vitamin that is made in the skin after being exposed in the sunlight. It is an essential vitamin for healthy growth and strong bones and muscles.

Although some foods (eg, oily fish and eggs) contain vitamin D, the vast majority of vitamin D we need is from the sunlight. To have adequate levels of vitamin D, it is recommended that people need to spend at least half an hour, two or three times a week in sunlight when their shadows are shorter than them (ie, the midday sun).

Vitamin D is not stored for long in our bodies, so this amount of exposure to the sun needs to be regular. In practice, this is actually very difficult to achieve in the UK and for that reason many of my patients, even those who are otherwise healthy, are being found to have low vitamin D levels. A low level is easily diagnosed by a simple blood test.

Growing children, pregnant women, and breast-feeding women need extra vitamin D because it is required for growth. The current recommendations by the Department of Health are for certain people to take vitamin D supplements regularly to avoid the risk of vitamin D deficiency. The amount of vitamin D needed is 10 μg (400 IU). This can be taken as tablets or as drops.

Certain groups of people have a higher risk of having low vitamin D levels. It is now recommended that the following people should all take daily vitamin D supplements:

  • Any woman who is breast-feeding or is pregnant
  • All children aged six months to five years
  • All adults over 65 years of age
  • People who have low or no exposure to the sun, for example those who cover their skin for cultural reasons, who are housebound or who are confined indoors for long periods
  • People who have darker skin, for example people of African, African-Caribbean or South Asian origin, because their bodies are not able to make as much vitamin D.

The vast majority of children and adults with low levels of vitamin D do not have any symptoms. Some people have vague symptoms such as tiredness or general aches and these often really improve with treatment.

If vitamin D deficiency is not treated, then children can develop rickets and adults can develop a condition called osteomalacia, which leads to muscle weakness and pains.

Low vitamin D levels in babies can also lead to muscle spasms occurring and even cause fits. Many children with low vitamin D levels do not grow as much as they should. Rickets leads to their bones being softer than normal and their legs can become curved (bow-legged).

Osteomalacia can lead to pains in the bones. Muscle weakness is more common in those people with vitamin D deficiency, so some people notice it is more difficult to walk up the stairs or to get out of a chair.

There is also some evidence that vitamin D may also help to prevent other diseases such as cancer,type 2 diabetes and heart disease.

So if you have any of these symptoms, or think you are at risk of having vitamin D deficiency, you should see your doctor.

Dr Louise R. NewsonBSc(Hons) MRChB(Hons) MRCP FRCGP is a GP and menopause expert, based in Solihull, West Midlands, UK.
Follow her on twitter: @mymenopausedr