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Vitamin D supplements do not prevent disease in the majority, says study

By Sally Robertson, BSc

Current evidence does not support that vitamin D supplementation does anything to help prevent disease among the majority of people, according to a new study published in the British Medical Journal (BMJ).

The finding comes from a study by researchers at the University of Aberdeen and University of Auckland, New Zealand.

Lead author of the paper Mark Bolland (University of Aberdeen) and colleagues say that clinical trials do not show that supplementation with the vitamin improves musculoskelatal outcomes such as falls and fractures. They advise that the only people who may benefit from supplementation are those at high risk of deficiency such as nursing home residents and darker-skinned individuals living in colder environments. For the rest of us, however, they say the focus should be on eating a healthy diet and getting regular exposure to short bursts of sunlight.

On sun exposure, the skin makes vitamin D, which helps maintain a sufficient level of calcium to keep the bones, teeth and muscles healthy. Deficiency can lead to conditions such as rickets in children and osteomalacia in adults. Most people get enough sun exposure during spring and summer, but in autumn and winter, exposure is limited and the main source of vitamin D is foods such as red meat, liver, oily fish and egg yolk.

Natural sources of Vit D

Public Health England therefore recommends that everybody should take 10 mg of vitamin D supplement every day throughout autumn and winter.

However, according to Bolland and team, their comprehensive review of published evidence from clinical trials on the impact of taking the supplements showed “no important effects on bone density nor any consistent effects on falls, total fracture, or hip fracture.” They also did not find any high quality evidence to suggest supplementation is beneficial for other conditions such as stroke and heart disease.

Vitamin D Supplements

The researchers says that vitamin D supplementation can be beneficial, but probably only among people with severe deficiency. They therefore suggest that individuals at high risk of deficiency should be advised about diet, sun exposure and low dose supplementation of the vitamin. However, as far as anyone else is concerned “supplementing at the Public Health England levels does not prevent falls or fractures,” says co-author of the paper Alison Avenell (University of Aberdeen).

Professor of genetic epidemiology at King’s College London, Tim Spector, also questions whether the Public Health England recommendation is evidence based. Despite hundreds of studies, he says, there is still no convincing evidence of a role for vitamin D supplementation. Aside from those at high risk of deficiency, he concludes:

the rest of us should avoid being ‘treated’ for this pseudodisease, save scarce NHS resources, and focus on having a healthy lifestyle, sunshine, and a diversity of real food”

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