With a rapidly aging US population, there's a growing demand for 'smart drugs,' or nootropics, which are meant to improve brain function.
The supplements are marketed as being able to 'enhance' the brain, promote creative thinking, and ward off cognitive decline and memory loss.
They've also become one of the fastest-growing segments of the supplement industry.
Now, Gizmodo reports new research from Harvard University shows such supplements often contain unapproved and potentially unsafe drugs.
The study detected in these 'brain-boosting' products ingredients unapproved by the US Food and Drug Administration.
It also found that these drugs could be in much higher doses than labeled, or in combinations that have never been tested in people.