I think that arguement is flawed since people have been using lots of harmful stuff for thousands of years. There has been research that suggests Zembrin is harmless but noone knows the effects in long term. If it has any positive effects on the brain, there are also likely side effects. Personally I'd worry about long term effects on neuropsychological capacities like memory, executive functions, and so on. Likely such side effects are subtle and only something to worry about if you continue to use the product for a long time. Just take care of your brain and health!