Supplements and systematic reviews

The Guardian published this.

The commissioning editor said

“1) Examine.com refused to be paid for this article. They refuse to have advertising on their site. Their only source of income is through their supplement guide, which collates the findings on the site.

2) That supplement guide uses a team of scientists to analyse the latest findings on supplements.

3) Although Spencer Nadolsky’s name appears on top of the article, the piece itself is a combined effort from Examine.com’s team. You can read more about them here: http://examine.com/about/

4) They actually ask for public contributions if you think they have missed any important studies/ research. You can submit such research here.

5) I asked them to look at the credibility behind the most popular supplements. They could equally have looked at five things that are a total waste of money: they are not “pro” supplement,

6) I think people may be missing the fact that every headline clicks through to the section on their site with citations to the relevant research.

Finally, to suggest that looking at the research into common vitamins and supplements is any way comparable to homeopathy is frankly ridiculous.”

 

The footnote to the piece says

This footnote was amended on 8 April 2014 to add information about Dr Spencer Nadolsky’s former links to Leaner Living. Examine.com is an independent encyclopedia on supplementation and nutrition. It does not accept advertising. Dr Nadolsky was a co-founder and owner of Leaner Living, a website which sells supplements. He no longer has any connection with Leaner Living, which is now run by his brother. The content written by Dr Nadolsky was verified by all five researchers at Examine.com”

 

Let us examine the evidence; for the comparison between bad science on supplements, and bad science on homeopathy isn’t far apart.

FISH OILS

http://jama.jamanetwork.com/article.aspx?articleid=1357266

“Overall, omega-3 PUFA supplementation was not associated with a lower risk of all-cause mortality, cardiac death, sudden death, myocardial infarction, or stroke based on relative and absolute measures of association.”

VITAMIN SUPPLEMENTS

http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD007176.pub2/abstract

“We found no evidence to support antioxidant supplements for primary or secondary prevention. Beta-carotene and vitamin E seem to increase mortality, and so may higher doses of vitamin A. Antioxidant supplements need to be considered as medicinal products and should undergo sufficient evaluation before marketing.”

GLUCOSAMINE

http://t.co/mT32yQzRzq

Compared with placebo, glucosamine, chondroitin, and their combination do not reduce joint pain or have an impact on narrowing of joint space. Health authorities and health insurers should not cover the costs of these preparations, and new prescriptions to patients who have not received treatment should be discouraged.”

VITAMIN D

http://www.bmj.com/content/348/bmj.g2035

“Despite a few hundred systematic reviews and meta-analyses, highly convincing evidence of a clear role of vitamin D does not exist for any outcome, but associations with a selection of outcomes are probable.”

 

Why are my conclusions so different?

Well, I’m relying on meta analyses and systematic reviews.

These look at ALL the available evidence – the small studies, the large studies, the well publicised and press released studies, the not so well press released studies – and analyse them together.

We know that negative results don’t make it into the journals so often – so it’s vital that researchers try and undo this bias as much as possible. Otherwise, we might start believing that  trials showing an intervention works are the only ones that exist.

This is why meta analyses and systematic reviews are so important. They aim to reduce known publication bias – and the cherry picking of the studies that some people draw on  in order to prove a point. Instead, these types of reviews put the whole knowledge of research on a subject together, and draw safer, more reliable conclusions.

It’s exactly the same with homeopathy. Fans will cite tiny unreliable studies as proof it works. But when you put it all together, like this  report released today, it’s plain that it doesn’t work. 

Mistakes are common, we all make them, I make them. It’s easy to get misled by the citing of individual studies to support supplements, or homoepathy, which sounds all good and sciencey. The problem is that there are other better studies with different conclusions, and we may not know about them. Science is all about uncertainty. Systematic reviews give us fairer, safer conclusions about what we can rely on.

 

One Response to “Supplements and systematic reviews”

  1. GM April 22, 2014 at 4:52 pm #

    You fixed their article!

    Much better :-)

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