Vitamin D has been in the news recently. In one report it was touted as the “cure” for infertility, while another announced that a quarter of UK toddlers were in danger of developing rickets due to a lack of Vitamin D. Is there any truth in either allegation?

Researchers in Austria considered all the published studies on the effect of Vitamin D in both male and female fertility and concluded that the vitamin does play a part in biological processes involved in sperm and ovary cells and that it could affect levels of sex hormones.

However the Daily Mail’s assertion that the cure for infertility is a holiday in the sun is overstating the case: the best conclusion is that there may be some connection between human fertility and Vitamin D levels. Many of the studies considered by the Austrian team used animals, not humans, and several studies contradicted each other, so the picture is far from clear.

One area where Vitamin D has been proven as beneficial is bone health, and a lack of the vitamin is definitely prejudicial. Without an adequate supply bones become thin and misshapen. Rickets is a condition involving softening of the bones in children, leading to deformity (typically bow-legs); in adults, bone softening is known as osteomalacia and causes pain and muscle weakness. Rickets is on the rise in the UK, but is still rare and certainly not at epidemic level as suggested by some newspaper reports.

Vitamin D also helps regulate levels of calcium and phosphate in the body, cell growth, inflammation, neuromuscular and immune function… the list goes on. Research is still being carried out into the – possibly many – other functions Vitamin D may be responsible for controlling. It is recognised as vital to general health.

The best source of the vitamin is through the skin from UVB rays in sunlight, as long as care is taken to avoid sunburn. It is hard to obtain enough Vitamin D purely from the diet (the best sources are oily fish, eggs and cheese), but it is added to many foods including baby-milk formulas, some breakfast cereals and soy milk.

Supplements are recommended for nursing mothers, small children, and those who cannot absorb the vitamin through their skin, such as the house-bound and people who cover their skin for cultural reasons.

Health professionals are being encouraged to offer advice on Vitamin D supplementation to those at risk, to avoid the largely preventable health problems associated with lack of the nutrient. Doctors should also be encouraging their patients to spend time out of doors, absorbing the vitamin naturally and effectively through their skin whenever possible.