...although certainly vitamin manufacturers could misrepresent the contents of their products. But at least the notation 500 IU D3 has some actual objective meaning, and is easily confirmed with testing. Determining whether herbal supplements in particular contain meaningful, standardized amounts of the herbs they claim to contain is another matter, as is determining whether they have ANY of those herbs at all. Or what their potency is. It's all voodoo, and multi-million dollar voodoo at that.

"My god how the money rolls in--
Rolls in, rolls in,
My god how the money rolls in, rolls in.
Rolls in, rolls in, my god how the money rolls in."

Vitamin D is a special case, as most modern humans do not spend enough time naked in the sun to produce as much as they might need. I take 1000 IU daily on my physician's recommendation because blood work showed exceedingly low serum levels of vitamin D-- I live in a cool, cloudy climate and spend most of my time indoors, clothed. Very little sun exposure on skin.