The problems with medical research
The headline article on Medscape this week was High-Dose Vitamin D Does Not Prevent Depression. As a practitioner who has observed the opposite in clinical practice I was keen to read the nuts and bolts of the research to see if the study participants and dosage differed to those of my clients.
The University of Melbourne study Annual high-dose vitamin D3 and mental well-being: randomised controlled trial recently published in the British Journal of Psychiatry was long term (3-5 years) and double-blinded.
They used the clinically proven form of Vitamin D – Vitamin D3 (versus D2).
The dosage of Vitamin D was in fact high, a whopping 500,000 iu, but given just once a year.
The question marks
The study was small, with only 102 subjects.
The subjects were women, over 70 yo, which was an interesting group to target. As I only have one or two clients on Vitamin D in this demographic, it’s difficult for me to compare my anecdotal results.
Were the older women depressed? Well that’s the interesting thing. The study looked at “preventing” clinical symptoms of depression, rather focusing on subjects who were already diagnosed as depressed or anxious.
Annual high dose Vitamin D versus smaller daily doses is controversial. Most naturopaths and Australian GP’s recommend a daily dose of between 1,000-5,000 iu.
The big dirty black cross
The declaration of interest of the authors involved in the study included Eli Lilly, GlaxoSmithKline, Organon, Mayne Pharma, Servia, Bristol-Myers Squibb, Novatis, AstraZeneca, Janssen-Cilag, Lundbeck, Pfizer, Sanofi Synthelabo, Solvay and Wyeth. That about covers all the manufacturers of anti-depressant drugs.
Very few journalists reporting medical research look beyond the carefully worded press release. In fact, the vast majority just reprints it. So the headline “High-Dose Vitamin D Does Not Prevent Depression” while only partially correct, perhaps gets away with promoting the subliminal message that this nutrient plays no role in the treatment of anyone’s depression. But why should a journalist dig any deeper when the research is from a leading educational institution such as the University of Melbourne? Unfortunately, the declaration of interest tells an interesting story, that of the role of big pharma in the funding of medical research in Australia.
While I am not disputing the credibility of the research, the choice of subjects for the study (elderly and not clinically depressed) is perhaps not the most useful in testing Vitamin D’s role in clinical depression. While the authors of the study are careful to not extrapolate their findings as representative of the wider community, those reporting it unfortunately may not be as precise.
Beyond the headline, my own anecdotal experience with men and women aged between 25-50, with sub clinical and clinical depression treated with a daily dose of 2,000- 4,000 iu of Vitamin D3, suggests more optimistic outcomes. While double-blinded, placebo controlled studies remain the gold standard in evidence based medicine, those at the coal face of clinical practice across the health disciplines can still benefit from experience and anecdotal evidence.