Many of us have wondered, how much coffee is too much? After all, it is one of the most popular beverages around the world. In fact, it is so popular with humans that traces of caffeine can be found in blood samples, says a new study.
While caffeine was found to be the most consistent external component in these human blood samples, other substances included cough medicine and Xanax. The study aimed at testing new methods to evaluate the potential for interactions between botanical dietary supplements and drug metabolism. The surprising results were recently published in the Journal of Pharmaceutical and Biomedical Analysis. 
“The study leads you in that direction, though without doing a comprehensive survey of vendors and blood banks we can only speculate on how widespread the problem is,” said Richard van Breemen, the director of Linus Pauling Institute at the Oregon State University. “Another thing to consider is that we found drugs that we just happened to be looking for in doing the drug interaction assay validation – how many others are in there too that we weren’t looking for?” 
The study involved mass spectrometry research of 18 batches of human blood serum. Apart from the aforementioned components, the researchers also tested the samples for tolbutamide, which is used in cases of type 2 diabetes, which was present in none of the samples. The results highlight the possibility of blood transfusion receivers getting contaminated with caffeine, cough medicine, and Xanax, an anti-anxiety drug.
Caffeine, while predominantly derived coffee beans, is also found in other sources such as tea leaves and cocoa beans. This further is made accessible to us through coffee, tea, soda, and more.
The research was supported by NIH’s Office of Dietary Supplements and the National Center for Complementary and Integrative Health.