Juiced-up Drugs
By Anthony Almada, M.S.

Think twice before you wash down any medication with a glass of juice—it may cause adverse reactions. Here's why: A variety of compounds found in grapefruit juice hinders the normal detoxification and metabolism processes in the intestines and liver. This exaggerates the effect of pharmaceuticals, because larger amounts of a drug may then be absorbed. For those who take medications that are only partially absorbed and metabolized—such as cyclosporin, felodipine, verapamil, triazolam and terfenadine—drinking grapefruit juice with the drug could mean more side effects and adverse reactions.

One of the identified culprits in grapefruit juice is the flavonoid naringenin. Orange juice also contains naringenin, but at one-tenth the concentration. Recent studies show that drinking either juice results in a significant increase in blood naringenin, suggesting orange juice, too, may inhibit the detox process and exaggerate drug effects. However, there do not appear to be any studies describing an orange juice-drug interaction.

Perhaps the takeaway message is, think before you drink—grapefruit juice, that is.

Nutrition and exercise biochemist Anthony Almada, M.S. has collaborated on more than 45 university-based studies and is founder and chief scientific officer of IMAGINutrition.