Everyone loves D, the sunshine vitamin. Doctors, patients and the media have been enamoured with vitamin D supplements for decades. As well as their clear benefit in curing severe vitamin D deficiencies, endless headlines hail their magical ability to reduce a vast range of conditions from dementia to cancer.
Medical specialists such as myself have been promoting supplements to our patients with osteoporosis and other bone problems for decades. Many food products contain artificially added vitamin D with the aim of preventing fractures and falls and improving muscle strength although the vitamin also has been claimed to boost the immune system and reduce ageing. I used to sometimes take vitamin D myself and recommended it to my family to survive sun-starved winters.
However, a new paper on the risks that vitamin D may pose finally has convinced me that I was wrong. My view on vitamin supplements and the multi-billion dollar industry behind them altered radically after I began researching my book, The Diet Myth, in 2013. The industry and its PR is supported by celebrities who reportedly have high-dose vitamins drip fed into their veins, and around 50% of Americans and Britons take them regularly. But surprisingly, there is a lack of evidence to support the health benefit claims of virtually all vitamin supplements on the market.
![](https://62e528761d0685343e1c-f3d1b99a743ffa4142d9d7f1978d9686.ssl.cf2.rackcdn.com/files/107275/width237/image-20160105-28997-schbqk.jpg)
One study based on the large SELECT trial suggested that supplements such as vitamin E and selenium actually increased prostate cancer in some men. And last year massive analyses combining 27 studies on half a million people concluded that taking vitamin and mineral supplements regularly failed to prevent cancer or heart disease. Not only are they a waste of money for the majority of us – but if taken in excessive quantities they can actually hasten an early death, increasing your risk of heart diseaseand cancer.
Virtually no vitamins or supplements have actually been shown to have any benefit in proper randomised trials in normal people without severe deficiencies. Rare exceptions have been lutein nutrients for macular degeneration, a common cause of blindness – and vitamin D, the golden boy of vitamins.
Since the 1980s, researchers (including myself) have written thousands of papers, associating a lack of our favourite vitamin with over 137 diseases. A 2014 BMJ report, however, found these links mainly to be spurious.
Won’t do you any harm?
Our genetic makeup influences vitamin D levels. We can use this information to tell if naturally low vitamin D levels might actually increase the risk of disease (rather than be a consequence of it). The evidence so far suggests (with the possible exception of multiple sclerosis and some cancers) that low vitamin D levels are either irrelevant or merely a marker of the disease.
Until now we haven’t worried about giving people extra vitamin D because we thought “it might help anyway and of course (as it’s a vitamin) doesn’t do you any harm”. With our increasing knowledge, we should now know better. Recent studies in the last five years have suggested that even calcium supplements as well as being ineffective in preventing fracture can increase the risk of heart disease.
While several studies in normal people failed to find any protective effects from vitamin D, others have been more worrying. One 2015 randomised study of 409 elderly people in Finland suggested that vitamin D failed to offer any benefits compared to placebo or exercise – and that fracture rates were, in fact, slightly higher.