Countless chemicals are absorbed from our diet every day and many of these compounds are as potent as drugs in terms of inhibiting and inducing CYP enzymes.
Grapefruit and other fruit juices, for example, have already been mentioned as being potent inhibitors of CYP3A4. Many food additives expose the consumer to compounds that induce CYP enzymes. For example, the process of barbecuing meats produces hydrocarbons that induce CYP1A2.
Cruciferous vegetables, such as cabbage, cauliflower, and Brussels sprouts, induce CYP1A2. Further, eating vegetables increases the pH of urine. This is beneficial in maintaining a number of conjugated metabolites of aromatic amines.
Caffeine is metabolized by CYP1A2. It is an inhibitor of substrates cleared by CYP1A2.
A change to a person’s diet can significantly alter the clearance of drugs and lead to loss of efficacy or possible toxicity.