It sounds like the drink is made from natural sources, so it probably contains compounds that he isn't aware of. The risk (and the value of the experimental results) would probably be higher if he had found a way to isolate the compounds in the drink so he could enumerate the exact chemical composition.

If there is a risk, it is that his diet is potentially more homogenous than a typical diet, and doesn't include anything from some class of foods that nearly everyone on a more heterogeneous diet eats occasionally.