Wednesday January 25 2012
Sunlight and supplements are both important sources of vitamin D
Vitamin D was in the headlines today, with many papers reporting that a quarter of all toddlers are deficient in the nutrient and that childhood rickets is on the rise. The vitamin plays several important roles in the body, including regulating the balance of nutrients needed for strong, healthy bones.
The vitamin has fallen under the spotlight as Chief Medical Officer for England, Professor Dame Sally Davies, is reportedly contacting health professionals to highlight the need to recommend vitamin D supplements to at-risk groups. There are already extensive guidelines on circumstances where people should take vitamin D supplements, but the move seems designed to increase use of the pills, which are available on prescription, or even free to individuals with a raised risk of deficiency.
An independent advisory committee is also reviewing current recommendations on vitamin D, but the results of this extensive analysis are not expected until 2014.
While vitamin D deficiency may have increased in recent years, rickets is still a rare condition. That said, it is largely preventable and vitamin D supplementation can be of great importance to at-risk groups such as toddlers and young children.
What is vitamin D and why do we need it?
Vitamin D plays an essential role in maintaining good health. It has several important functions, including helping to regulate the amount of calcium and phosphate in the body. These substances are needed to keep bones and teeth healthy.
Without adequate vitamin D, bones can become thin, brittle and misshapen. In extreme cases this can lead to rickets in children, a condition involving a softening of the bones that can lead to fractures and deformity. In adults softening of the bones is usually called osteomalacia, and may cause pain and muscle weakness.
Vitamin D may have other important roles in the body including regulating cell growth, neuromuscular and immune function, and reduction of inflammation. Even years after its discovery, there is still ongoing research examining the various other functions vitamin D might perform in the body.
According to the Scientific Advisory Committee on Nutrition (SACN) – a group of experts that advises the government about all aspects of nutrition – some evidence suggests that vitamin D may be important in preventing other diseases including cancer, cardiovascular disease and multiple sclerosis, although it points out further research is needed before any definite conclusions can be drawn.
How can I get vitamin D?
The best source of vitamin D is sunlight on the skin. The vitamin forms under the skin in reaction to a type of ultraviolet ray called UVB. UVB rays are more powerful in the summer, and experts advise exposing the skin to regular, short periods of sun during the summer months, without sunscreen, which blocks UVB rays. However, it is important to ensure that the skin does not burn.
Vitamin D is also found in a small number of foods but it is difficult to obtain enough vitamin D from diet alone. Good sources of vitamin D include oily fish (such as salmon and sardines) and eggs. In the UK, infant formula and fat spreads are fortified with vitamin D. It is also added to other foods such as breakfast cereals.
Vitamin D is also available in supplement form.
Who is at risk of not getting enough vitamin D?
The current advice is that most people should be able to get all the vitamin D they need by getting enough sun and eating a healthy balanced diet. However, the Department of Health says the following people may be at risk of vitamin D deficiency:
- all pregnant and breastfeeding women
- all children aged under five years old
- all people aged 65 or over
- people who are not exposed to much sun – for example people who are housebound (confined indoors for long periods) and those who cover up their skin for cultural reasons
- people who have darker skin, such as people of African, African Caribbean and south Asian origin, because their bodies are less able to produce as much vitamin D.
Who needs vitamin D supplements?
The Department of Health recommends:
- All pregnant and breastfeeding women should take a daily supplement containing 10 micrograms of vitamin D. This is to ensure the mother’s requirement for vitamin D are met and to build adequate fetal stores for early infancy.
- All babies and young children aged 6 months to 5 years should take a daily supplement containing vitamin D in the form of vitamin drops, to help them to meet the requirement set for this age group (7-8.5 micrograms of vitamin D per day). However, those babies who are fed infant formula milk will not need vitamin drops until they are receiving less than 500ml (about a pint) of infant formula a day, as these products are fortified with vitamin D. Breastfed infants may need to receive drops containing vitamin D from one month of age if their mother has not taken vitamin D supplements throughout pregnancy.
- People aged 65 years and over and people who are not exposed to much sun should take a daily supplement containing 10 micrograms of vitamin D.
You can buy single vitamin D supplements at most pharmacies and supermarkets. Women and children eligible for or participating in Healthy Start can get free supplements containing vitamin D.
Pregnant women who take vitamin D as part of a multivitamin should avoid supplements containing vitamin A (retinol), which can be harmful in pregnancy.
Can too much vitamin D be harmful?
The Department of Health says that taking 25 micrograms (0.025mg) or less a day of vitamin D supplements is unlikely to cause any harm.
Is rickets really on the rise?
Yes. In 2007 SACN published an update paper on vitamin D which, it said, highlighted “the prevalence of low vitamin D status throughout the UK population and the re-emergence of rickets in certain subgroups”.
However, while it would appear that a relatively high proportion of children do not get enough vitamin D, rickets is still a rare disease in the UK and there is certainly not an epidemic of the condition, as might be supposed by reading some news articles. That said, the condition is largely preventable, and so there is a need to ensure parents and children have access to vitamin D supplements wherever appropriate, such as through the Healthy Start scheme.
What will happen next?
Last year the government launched a review of vitamin D supplementation, which is due to report in the next few years. In the meantime, Dame Sally is reportedly contacting health professionals to ensure they offer advice on vitamin D supplementation to those at risk, so that they can avoid health problems associated with deficiencies of this important nutrient.