One big problem is that the "nutritional" industry, which amount to well-spoken charlatans. They make outlandish, unprovable claims, and people swallow it (literally) by the billions.
They masquerade marketing as science in order feign legitimacy, and the fact is they aren't providing anything with a provable benefit.
The only regulatory bar they have to cross is that it's not obviously harmful. There's no requirement that the 'supplement' be beneficial.
It's bad enough to claim that some herb or vitamin supplement provides health benefits that are nonexistent. It's another thing entirely to sell a product that doesn't even have what is on the label. This morning, ABC news had a story about a number of nutritional companies were forced to pull their 'supplements' after testing proved they didn't contain anything they claimed to have.
I wish I could say I'm surprised, but after working for such a company, I have few doubts: the entire industry is rotten to the core, and is only interested in fooling their customers into buying snake oil. It's not like it's an insular thing; you're have to be aware of what the competition is doing, and I saw the same BS everywhere.