January 21st, 2012

All too often many companies that sell dietary supplements quote published studies saying that their product was shown to demonstrate a certain health benefit in a study published in some scientific sounding journal.

To be an informed consumer (and not waste your money), it is important to understand when the quoted study is credible and actually increases the odds of the particular product helping you.

Studies that, all though interesting, cannot be relied upon, are:

1-     Studies that were done on animals and not humans. Unfortunately, many ingredients that demonstrate a therapeutic benefit in rats, mice or rabbits, don’t show benefits in humans

2-     In-vitro studies are studies done outside of a living organism, in a test tube or petri dish. These studies offer zero comfort that the product will work for you.

3-     Even studies that are in humans cannot always be relied upon. Sometimes the number of people tested is so small that the results may not be reproducible. Sometimes the study reports positive benefits, but the magnitude of the benefits is so small that the product is not worth buying.  (For example a product that reports weight loss, but the weight loss is one half pound per month, which would not be acceptable to many purchasers.) The study didn’t compare the product to a placebo (known as a sugar-pill, but really any pill that has no active ingredients in it) or other product proven to work.  Especially when it comes to measuring things that are subjective like pain, comfort, pleasure, etc. just believing that the pill will work causes some people to report positive results even though they took the placebo (which is known to do nothing).

So look for studies that:

1-     Are placebo controlled studies in humans that report P-Values of .05 or smaller (P-values represent the odds that the reported benefit of the product was a matter or chance or luck.)  .05 means that that there was a 5% chance of the results occurring due to chance and not the therapeutic efficacy of the product. The lower the P-Value the more likely it is that the product works!

2-     Look for studies that are published in peer-reviewed journals.  This means that before the study is published experts in the field review the article to make sure that the science was done and reported correctly.  You can go on the internet and check whether any given journal is peer-reviewed.


Curt Hendirx, M.S., C.C.N., C.N.S.