Before I buy certain brands of vitamins, I would like to know which supplement companies live up to the claims as to what their nutrients contain. Any help with that would be appreciated. Because one company I was buying got a low rating because it had lower amount of what they claim to have. I want to avoid that mistake as much as possible.

Thanks in advance.

It's going to require research, and a lot of it. This site is a free site, and the volunteers that answer questions here, aren't paid to do so. You want a list of vitamin supplement companies that offer the best product. That's a lot of work research wise. I suggest you do that research.

I saw a show on PBS about supplements and how there is no regulation of them and how a vitamin D 400 IU tablet could actually contain 5000 IU, or vice versa. Sometimes the supplement did not even contain the actual vitamin or herb! However, they did mention Natural Factors, located in Canada, as one of the most reputable, high quality manufacturers, with stringent quality control and testing procedures. After seeing the program, I try to buy only Natural Factors products.