I would be very concerned about contaminants in collagen supplements. If you look at studies of, for example, bone broths cooked with 1) only meat, 2) meat and

I would be very concerned about contaminants in collagen supplements. If you look at studies of, for example, bone broths cooked with 1) only meat, 2) meat and bones, or 3) meat, bones, and skin, the amount of lead rises significantly with the additions of skin and cartilage included with the bones [1]. Another study[2] indicates that in the form of bone broth, the levels of lead and cadmium are acceptable because they're only a few μg, but my concern rises when you'd be potentially reducing a fluid like bone broth into a powder and consuming quite a bit of it at a time. The supplement industry is notorious for substandard or absent testing, so it wouldn't surprise me in the slightest if some bottles of collagen pills may contain several μg. If you take 5, then eat other foods with relatively high contamination, over time this habit seems like it has potential to significantly increase the heavy metal content in your body. I don't mean to be a scare-monger at all, and if someone knows more about this then please feel free to let me know I'm crazy. [1] https://pubmed.ncbi.nlm.nih.gov/23375414/ https://pubmed.ncbi.nlm.nih.gov/23375414/ [2] https://pubmed.ncbi.nlm.nih.gov/28804437/ https://pubmed.ncbi.nlm.nih.gov/28804437/