Getting More of the Sunshine Vitamin

I never thought I would ever be writing about a deficiency disease in a western country but the last few years have seen a steady increase in the number of cases of rickets in children and osteomalacia in adults as a consequence of vitamin D deficiency. Whilst this is surprising, given the relative abundance of foods in the UK (compared to the poverty stricken nations of the developing world where rickets in children is still an issue), very few people realise that getting this vitamin from food is actually only a part of the acquisition process of this essential micronutrient. To appreciate the true importance of this vital vitamin, we need to understand its role in the body and the consequences of not having enough of it, particularly on a long term basis.

Vitamin D is not only a nutrient, it is also a hormone. It is made from an essential component of cholesterol and therefore a key constituent in steroid hormones; cholesterol is needed for the production of the male and female sex hormones (oestrogens and androgens). Crucially however, vitamin D is needed for the absorption of calcium which is essential in growing children in order to strengthen their developing bones. A failure to absorb calcium leads to the classic hallmarks of rickets or 'bow legs' that develop when the weight-being joints (hips, backbone and knees) and associated bones cannot support the increasing weight of the developing body. Vitamin D in the form of D3 (or cholecalciferol) is one of the many naturally-occuring vitamins. The greatest source of this vitamin is the sun, being made upon the skin being exposed to the sun (hence the term 'sunshine vitamin'). It is the UVB rays (ultraviolet B) that convert cholesterol to vitamin D3. Darker skins need more UVB due to the protective elements of melanin; the rays have to penetrate the skin deeper in order to have the same effect as in a fair-skinned person. Direct exposure is necessary so sitting indoors is not good enough as the glass offers some filtering and depending on the type of glass, UVB may not even get through. 2-3 exposures of sunlight per week (20-30minutes an episode) in the summer months (April-September) is the recommended dose to achieve healthy vitamin D levels that last through the year. This is not the same as sunbathing and possibly not in the afternoon as the sun is much stronger at this time of day and can burn the skin. Morning sun is best.

In its hormonal role, vitamin D3 (now referred to as calcitrol) produces a steroid hormone called secosteroid which pays an important part in the regulation of the levels of calcium and phosphorus (another important mineral for the body). Vitamin D3 also helps to regulate bone mineralisation.

What's really shocking is that even health professionals are unaware of the government's guidelines and health education programme on this need to advise patients on vitamin D intake. Given that the issue of rickets in UK children was highlighted as a concern over 2-3 years ago, it is worrying to learn that even more recently, professionals remain ignorant of the need to educate and inform. What has really brought this issue to the forefront of course is a legal case against parents of a child who died of rickets (diagnosed after death) being wrongly accused of murder. Even senior radiologists were unable to spot the clinical features of rickets which was later attributed as the cause of death.

At risk groups:

• pregnant women
• breast-fed babies (infant formula has been fortified with vitamin D)
• young children (especially those under 5 years of age)
• dark-skinned individuals
• elderly people who are housebound
• those who are ill & bed-ridden
• those who stay indoors a lot
• those who cover up (for religious, cultural or other reasons)

Other diseases linked to lack of vitamin D:

• cardiomyopathy (a disease of the heart muscle) - babies
• hypocalcemic fits ((low serum calcium levels) - babies
• SIDS (sudden infant death syndrome)

Fear of Skin Cancer?

Recent fears over skin cancers and excessive sun exposure has probably contributed to the concern over exposing children to direct sunlight. Over the years, recommendations have always focussed on the risks of sunlight in favour of its enormous benefits and this increase in cases of rickets may well be a consequence of the advice being taken too far.

Use of Sunscreens

Many parents worry about the damaging effects of the sun but this is only possible if adequate precaution is not taken eg. over exposure in strong sunlight (between 10am-4pm in the summer months) for long periods of time, not in short bursts. Over protectiveness and a fear of danger which stops children playing outside and the excesive use of sunscreen has probably contributed to the health issues associated with a lack of vitamin D particularly the increased incidence of rickets in children.

Strategies for tackling the problem:

The solution is really very simple. Take steps to get more vitamin D! In the first instance, if the deficiency is severe, supplementation (sometimes in the form of injections) of vitamin D3 is essential. Thereafter and as a management strategy, dietary measures should be implemented to include foods containing natural forms of the vitamin. In plants, vitamin D exists as D2 and is only really found naturally-occuring in shiitake mushrooms. Most other plant food sources have been fortified with vitamin D. The best sources are from animals: fatty fish (mackerel, sardines, trout, herring, tuna, salmon, pilchards) and egg yolk. Limited use of sunscreens and sensible exposure to sunlight on bare skin (face, arms & legs) is vital.

If you are worried about your vitamin D levels, a simple blood test from your doctor should confirm if supplementation is necessary. Symptoms can also be verified through X-Rays and in some cases, bone density scans to check calcium absorption and mineralisation.

For more information and advice, you can visit NHS Direct (www.nhsdirect.nhs.uk/en) or Patient UK (www.patient.co.uk)