Dr Paul Clayton 2005


Bone health is a growing concern. In Europe, osteoporosis causes around 1.1 million fractures each year, and our increasingly elderly population suggests that these figures will worsen in the future. The widespread use of calcium supplements has been almost totally ineffective, so we urgently need to look for more effective forms of bone protection. A group of important new studies points the way forward.

In one worrying piece of research (Gallacher et al ’05), an analysis of hip fracture patients admitted to hospital in Glasgow found that 97.8% of them had sub-normal levels of vitamin D; in 25% of the patients, vitamin D levels were so low they could not even be measured. Ah, you might say, Glasgow is a special case – and indeed it is. With the lowest life expectancy in the UK, Glaswegians smoke too much, drink too much and eat one of the worst diets you’d ever be likely to encounter. (Unless, of course, you actually enjoy deep-fried pizza.) To make matters worse Glasgow is a Northern city, and the relatively short summer means there is little opportunity to expose pallid Scottish skin to the sun’s rays, which is necessary to make your own vitamin D. And to make matters worse still, the skin cancer scares of the 90s led people to shun the sun even more – even though the experts increasingly believe (Giovanucci ’06) that vitamin D reduces the risk of cancer!

In a related study carried out in Finland, another country with short summers, researchers in Reykjavik came to a similar conclusion (Steingrimsdottir et al ’05). The evidence in their large-scale study of 900 Finns strongly suggested that when it comes to bone health, the huge doses of calcium that are currently recommended are unnecessary (and possibly counter-productive) provided that there is enough vitamin D in the system.

This is not actually a brand-new concept. As the authors themselves state, “There is already sufficient evidence from numerous studies for physicians and general practitioners to emphasise to a much greater extent the importance of vitamin D status and recommend vitamin D supplements for the general public, when sun exposure and dietary sources are insufficient”.

From Finland we travel to Australia, a land known for sunshine and healthy outdoor activities such as beer, barbeques and ballroom dancing. You wouldn’t think that the Aussies had vitamin D problems, but even in the Antipodes vitamin D supplements have been shown to reduce the risk of bone fractures (Flicker et al ’05). This was a particularly interesting paper because the authors found that in elderly subjects, vitamin D supplements decreased the risks of falls and fractures by a third even in those who had so-called ‘normal’ levels of vitamin D at the start of the study. This in turn shows that the ‘normal’ levels of vitamin D have been set too low, and need to be urgently re-evaluated; a process which has already got underway in the USA.

In the light of this and other research, some countries such as the UK and Denmark have belatedly begun recommending that specific groups of the population take vitamin D supplements to ensure adequate vitamin D status during periods when there is little exposure to sunshine. But this message does not seem to have reached many consumers, or their GPs. With a mere 4 per cent share of the overall vitamins market, vitamin D lags a long way behind calcium in bone supplement sales.


References

1 Gallacher SJ, McQuillian C, Harkness M, Finlay F, Gallagher AP, Dixon T: Prevalence of vitamin D inadequacy in Scottish adults with non-vertebral fragility fractures, Curr Med Res Opin 2005 Sep, 21(9):1355- 61.

2 Giovannucci E: The epidemiology of vitamin D and colorectal cancer: recent findings, Curr Opin Gastroenterol 2006 Jan, 22(1):24-29

3 Flicker L, Macinnis R, Stein M, Scherer S, Mead K, Nowson C: Vitamin D to prevent falls in older people in residential care, Asia Pac J Clin Nutr 2005, 14 Suppl:S18.

4 Steingrimsdottir L, Gunnarsson O, Indridason OS, Franzson L, Sigurdsson G: Relationship between serum parathyroid hormone levels, vitamin D sufficiency, and calcium intake, JAMA 2005 Nov 9, 294(18):2336-41.