Studies on how people transform the substances that they ingest began in the mid-nineteenth century, with chemists discovering that organic chemicals such as benzaldehyde could be oxidized and conjugated to amino acids in the human body.
Os estudos de como as persoas transforman as substancias que inxiren empezaron a mediados do século XIX, cando os químicos descubriron que os compostos orgánicos como o benzaldehido podían ser oxidados e conxugados a aminoácidos no corpo humano.