Monday, November 8, 2010

Sensationalist news reporting: Vitamin E supplements lead to stroke

The media love to have catching headlines. Therefore anything that is controversial is in their interest to print. Hence any study that comes out showing that supplements don't work gets published. The only problem is that they don't publish the overwhelming number of studies that show the opposite.

The weekends headline "Vitamin E linked to risk of certain types of stroke" is no exception.  

Firstly most studies that show supplements don't work have the following technique.
  1. Researchers go out and interview the population. They ask "do you take supplements". If the answer is yes, then the move onto the next question such as health issues, or they come back years later and find out what disease(s) that person has.
  2. Data miners then troll this data to determine correlation between supplements and a disease
What is immediately obvious is that there is no quality questions around what type of supplements. There are some supplement brands that I wouldn't take, nor feed to my kids, even if they were free. There is very little done around the quality of the supplement, what it contains, are the compounds natural or manufactured, are they bioavailable etc. etc. Sensationalist

So the vitamin E study didn't look at if the vitamin E was natural or synthetic. This is important because there is preliminary data that seems to indicate that synthetic vitamin E is treated like a poison in the body. I would never take a supplement that had synthetic vitamin E in it.

Secondly there was no indication at what dosage level this increase was associated with. There is a massive difference between a supplement that has the RDI of vitamin E (from memory is approx 60 IU's) and what is considered a ODA of 200 - 300 IU's and a mega doses which might be 1000+ IU's. There is such a massive difference, I can't understand how they can be lumped together.     

Not only this, berried in the newspaper article is:
[vitamin E] increased the risk of hemorrhagic stroke, where bleeding occurs in the brain, by 22 percent, but cuts the risk of ischaemic stroke by 10 percent
So the increase in probability of a stroke is likely only 12%. It may in fact be lower depending on the probabilities of the different types of strokes (ie if probability of hemorrhagic stroke is 1% and ischaemic stroke 99 %, then a 22% in crease in hemorrhagic stroke is a negligible increase, compared to the 10% decrease in ischaemic stroke).

Therefore what can we conclude from the newspaper article? Nothing ! Except that reporters and newspaper articles are useless for obtaining relevant supplement information.

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