Independent lab testing for contaminants and actual active ingredient levels vs. what's stated. They also publish summaries of studies on the active ingredients that test the effectiveness against claimed therapeutic value. (It's depressing how few studies actually show benefit over placebo.)

> It's depressing how few studies actually show benefit over placebo

Look at it another way, isn’t it good to know you probably don’t need suplements.

Also, not surprising. The odds of snake oil actually curing anything are likely to hover just above zero (while bad side effects hover much higher).

If it isn't proven with multiple, independent studies, it is snake oil.

Even then, if the effect size is tiny it's little better. Almost every time I see some supplement that's supported by good studies the effect is always minuscule.

Shout out to examine.com, they also do a great job summarizing studies on supplements.