The website https://www.consumerlab.com/ might be close to what you're looking for, though it does require a subscription. I started researching things there after learning that many powdered protein supplements contained high levels of heavy metals.
Thanks for this - you inspired me to finally get a library card!
Unfortunately I can’t find anything on ConsumerLab about my go-to unflavored whey protein powder (Natural Factors). I guess no news is better than bad news.
They do independent testing for supplements and provide rankings based on detected ingredient, heavy metals and adulterants per serving (I linked protein but they also test other types of supplements). My only complaint is that their database is limited so you may not find the brand you are looking for.
