The FDA in The US has been trying to take over regulating the vitamins industry.
What this does, what it has done in the past, is not make anything better, it just costs more, because they need people to do the regulation paperwork. And it slows down the entire manufacturing process, so you get less fresh of a product.

Some studies have also suggested

Some studies are really stupid!
Some people suggest that all medical conditions are attributable to lack of nutrition.

The truth is... somewhere in the middle? really wonky?
Like, Vitamin C. Its like only 10% of it gets into the body from a pill form. Liposomal C is more readily uptaken... but, if your body has enough C in the system, more really doesn't help. But, if it has too little, all kinds of things break down.