There is a major difference in brands of supplements, particularly in the US where the FDA doesn't regulate them, like people (me) assume they would. You've got a double whammy, unless things have changed. First, the amounts stated on the bottles could be fabricated. Like I said, the FDA doesn't really oversee that. If a Vitamin C tablet claims it has 100 mg of vitamin C.....maybe it does, maybe it doesn't. Second, even when capsules do contain what they say they do, there's something called bio-availability, which is basically an absorption thing. A supplement can truly contain X mg of something, but that doesn't mean your body will absorb X mg. Depending on the bio-chemical mumbo-jumbo--CD would probably know more about that--you can swallow something, your digestive system can get a hold of it, and you may urinate (or the other thing) it out without the target chemical really getting into your body. So you might as well not have taken anything at all.
There are some reputable companies who have at least some amount of studies to back up their claim that you'll actually get the benefit of X mg of whatever. Some doctor's offices sell those. Most docs I've seen don't care one way or the other, partly because they know lots of pills are trash, and partly because they just don't care about that kind of stuff.
I take a few supplements. One is to combat the formation of kidney stones, one is to help joints. I've had noticeable success with those, and the results are measurable, tangible, and repeatable. I take a few others for other things that I honestly can't tell the difference. But the wife is happier with me taking them, so.....
