I'm gonna take it a step farther though, and say that most likely, all supplements are a sham. We already know that glucosamine and shark cartilage don't actually do anything for joints; vitamin megadoses don't make you healthier and may have adverse side effects over the long term. Alternative medicine supplements like Echinacea don't work. In fact, in all the years I've been following supplements, there's only one that I've seen with good, strong evidence that it's safe and effective: creatine monohydrate. But of course, you rarely find pure creatine monohydrate anymore. Now, every manufacturer under the sun has some uber-creatine concoction they claim is better absorbed than 'regular' creatine. Oh, and fish oil may be worth taking (of course, you could also just eat more fish).
How can they get away with this? How can all these companies market products with no evidence that they actually work? Well, we can thank Orrin Hatch and his 1994 legislation the DHSEA. From Steve Novella:
It should also be pointed out that in the US, due to DSHEA (a 1994 act that essentially removed supplements from FDA oversight) supplement manufacturers can put any combination of herbs and nutrients into a pill and make whatever claims they wish about it (as long as they don’t name a specific disease), without any burden of evidence. Right now you could throw darts at a dartboard with various herbs, minerals, and vitamins on it to come up with a random formula, and then spin a wheel of indications (boosts the immune system, improves metabolism, supports cellular function – whatever) and then market your random ingredients for your random indication, all without a lick of evidence. You can even claim your product was “scientifically formulated.” Now all you need are some anecdotes, but they are easy to come by. If you’re ambitious you can find an MD or PhD to endorse your product in exchange for a piece of the company. Don’t worry, as long as you don’t make a disease claim (directly – that’s what the anecdotes are for) and you put the quack disclaimer on your website, the FDA can’t touch you.This another great example of why libertarianism is bullshit. A libertarian would say that the government has no business getting involved in regulation of the industry – companies that put out bogus or just plain ineffective supplements would eventually get weeded out of the market. And yet nearly 20 years after the passage of the DSHEA, there are more bogus products on the market than ever, despite the fact that there's hard proof many of them don't work and may in some cases be dangerous.
Problem is, there's this pesky thing called the placebo effect. People are notoriously awful at objectively assessing the efficacy of a supplement or medicine. That's why we have placebo-controlled research. And access to information is also a hurdle – the supplement industry is a multi-billion dollar industry, which means they have a much easier time marketing bullshit than researchers do marketing facts. Not to mention that people tend to be guilty of wishful thinking – we want supplement claims to be true (because who wouldn't want an easier time losing weight and building muscle?), and we don't want to go around believing that people are liars for selling us that stuff.
Besides, as a commenter on Novella's blog pointed out, what is in the best interest of the consumer is not necessarily in the best interest of the business. Competition drives businesses to increase their market share by whatever means is most effective, and improving the actual product may be a ways down on the list – more persuasive and pervasive marketing is, as history has shown, the logical first step.
Safety is perhaps the most obvious reason, though. It can be very difficult to trace side effects to specific supplements, particularly since risk may involve long-term use; even the claims that ephedrine and certain prohormones were dangerous, which led them to be banned, were anecdotal. Only controlled clinical research can really reveal whether a supplement is safe. And if it's not, then what of all the people who took the supplements unaware of the risks – are they just collateral damage?
What is needed here is clear: more government oversight. Hell, it'd be easy enough to pass legislation that categorized increase muscle size or strength, weight or fat loss, and improved athletic performance as medical claims. But really, the supplement industry needs to go. It needs to be crushed, destroyed, and utterly dismantled. It's a whole industry that exploits people's wishful thinking with false claims and ineffective, even dangerous products. The DSHEA is a failure, and it's time for change. The burden needs to be on the supplement industry to provide clinical proof of the safety and efficacy of their products before they hit the market.