You’ve probably heard that grapefruit juice shouldn’t be taken with medications because a chemical quirk in the juice boosts the potency of certain drugs, increasing the risk of a dangerous overdose.
An article in the New York Times reveals how researchers stumbled on the grapefruit juice quirk. In 1989, a Canadian research team was looking for a way to mask the taste of alcohol for a study designed to examine the effects of alcohol on patients who were using a blood pressure drug. Grapefruit juice successfully covered the alcohol taste, but it also significantly raised blood levels of the medication.
At first, the medical establishment didn’t buy the discovery, but further research has uncovered the mechanism that produces the potency boosting effect. It appears that grapefruit juice impedes an enzyme that plays a key role in metabolizing some drugs. When the effect of the enzyme is derailed, more of a drug’s active ingredient reaches the bloodstream.
The enzyme – known as CYP 3A4 – may also be affected by apple juice, lime juice and orange juice made from Seville oranges. These juices should also be avoided with cholesterol lowering statin drugs (such as Lipitor), selective serotonin reuptake inhibitors (such as Prozac) and, as mentioned above, drugs that manage blood pressure.
Researchers note that the effect grapefruit juice has on specific drugs may vary from patient to patient.