Supplementing with vitamin D gives few benefits, if any.
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Low levels of vitamin D is linked to a range of different conditions.
That’s guaranteed to get some scientist excited and supplement companies even more excited.
But correlation isn’t causation.
So is supplementing with vitamin D actually useful?
Vitamin D supplementation has few, if any, health benefits according to a recent review.
The study examined the evidence for 10 common beliefs about vitamin D.
The beliefs include vitamin D’s ability to:
- Reduce falls;
- Reduce fractures;
- Reduce respiratory tract infections;
- Improve depression and mental well-being;
- Prevent rheumatoid arthritis;
- Treat Multiple Sclerosis;
- Reduce cancer incidence and mortality;
- Reduce mortality;
- Be more effective in higher doses; and
- Vitamin D levels should be routinely tested.
Overall, the review found little evidence that vitamin D supplementation had any effect at all.
There were a few beliefs that had some scientific evidence.
Strongest was vitamin D has a minor impact in reducing the number of falls among the elderly and in reducing fractures.
But even here the evidence was weak.
Lead researcher Dr. Mike Allan, professor of Family Medicine and director of Evidence Based Medicine at the University of Alberta’s Faculty of Medicine & Dentistry said:
Even areas that we really thought there was good evidence for benefit early on, don’t seem to be bearing out
The one that we probably have the most evidence for is fractures.
If you were to take a group of people who were at higher risk of breaking a bone–so had about a 15 per cent chance of breaking a bone over the next 10 years–and treated all of them with a reasonable dose of vitamin D for a decade, you’d prevent a fracture in around one in 50 of them over that time.
Dr. Allan continued:
other possible benefits of vitamin D covered in the review were not borne out or are still unproven
But belief in the benefits of vitamin D supplementation remains strong despite the lack of evidence for effectiveness.
Dr. Allan believes much of that stems from misplaced trust in earlier research studies showing low vitamin D levels are associated with poor health outcomes.
But association doesn’t prove causation.
Dr. Allan commented:
Much of the existing research around vitamin D was poorly executed and consists of poor quality evidence.
Moving forward research in the area needs to be of a higher caliber to be of clinical relevance.
It makes it really difficult to determine a lot of time if there is anything substantial there that you could tell a patient, ‘You can take this and it can help you this much.’ There’s really not nearly enough there to say that.
So what’s the takeaway from all this then?
Dr Allan said:
The bottom line is that while moderate vitamin D supplementation won’t cause harm to the average healthy person, it won’t heal either.
The 40 year old person is highly unlikely to benefit from vitamin D.
And when I say highly unlikely, I mean it’s not measurable in present science.
The study was published in the Journal of General Internal Medicine (Allan et. al., 2016)
Image credit: the independent