A Potential Design Flaw of Randomized Trials of Vitamin Supplements

[natasa778]

This came up in a thread on q10 supplement study on GWS veterans, where it was found to have positive effects at 100mg and negative or no effects at 300mg.

The authors noted that Dose Consideration was:
"Nonmonotonic.
This is the norm for antioxidants: many are prooxidant at higher doses. BUT point of transition varies.
This is common for nutrients: Supplement trials often err by thinking if some is good, more is
better" and quote this study http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3393521/

 

[barbc56]

The public health may be better served by initially conducting trials in individuals with insufficient nutriture and, if effective, further testing the effectiveness in those with adequate nutrient levels

.

I think this sounds like a good idea.

Something I have always wondered about is the source of the vitamins used for studies. Is this information provided in a written study? Do they get prescription grade vitamins and supplements?

In the US, supplements are not regulated like pharmaceutical drugs, so what it says on the label is not necessarily the actual contents. This could make results of a study not valid if the vitamins and supplements most people take are OTC.

Barb

 

[adreno]

In the US, supplements are not regulated like pharmaceutical drugs, so what it says on the label is not necessarily the actual contents. This could make results of a study not valid if the vitamins and supplements most people take are OTC.

Sometimes the brand is specified in the study, but not always. However, participants are not allowed to take whatever they want.

You can buy high quality supplements OTC. Although not required, several companies voluntarily submit their products to 3rd party testing and inspection. For example, Thorne Research, and Life Extension. They cost more than what you pay at your local supermarket, though.