How Fruit Juices Affect Medication

What would you think of somebody who poured himself a vodka martini for breakfast every day? No doubt you would believe he was on a rocky road to medical hell. But how many readers are aware that a large glass of grapefruit juice in the morning is also a health hazard? Studies show that downing a glass of fruit juice can have a powerful effect on medication.

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In 1991, Dr. David Bailey, an expert on clinical pharmacology at the University of Western Ontario, was the first scientist in the world to discover that grapefruit juice had the ability to increase the level of certain drugs in the blood. At the time it was considered a mere academic curiosity. But what Dr. Bailey had discovered was just the tip of the iceberg. Later it was discovered that grapefruit juice increases the blood level of one cholesterol-lowering drug (CLD), by as much as 15 times. It was the same as if a patient had taken 15 times the recommended dose of the drug! This increased the risk of developing rhabdomyolysis, which causes a breakdown of muscle tissue and possible kidney failure. This is a huge price to pay for lowering blood cholesterol. Dr. Bailey reported at that time that the effect of grapefruit juice lasts for several hours. He said, “There’s a real possibility that if a patient took the CLD with grapefruit juice for two or three weeks he would develop this complication.” I found this research at the time rather frightening, as who in their wildest dreams would have thought that drinking grapefruit juice was living on the edge? The manufacturers of the CLDs agreed that grapefruit juice could elevate CLD levels in the blood. But the pharmaceutical company stressed that Finnish researchers had used unrealistic amounts of grapefruit juice during the study—and that not a single case of rhabdomyolysis had been documented in over 30 million patients. But Dr. Bailey contended: “The fact that there is not a reported serious interaction between grapefruit juice and this CLD did not show that it did not exist. It may have not been recognized because of a lack of awareness.” In other words, what you don’t look for, you don’t find. Now, 17 years later, Dr. Bailey has made another shocking discovery. He recently reported to the American Chemical Society’s national meeting in Philadelphia that grapefruit, orange, and apple juice can decrease the absorption of certain drugs such as those to treat cancer, heart disease, and those used after organ transplantation—a rather worrying situation if these drugs are essential to your survival. To determine this effect, Dr. Bailey and his colleagues gave an antihistamine drug to healthy volunteers. Some volunteers were given grapefruit juice along with the antihistamine. Others were given a glass of water containing narigin, the ingredient that makes grapefruit taste bitter, and the last group received only water. They found that only half of the antihistamine drug was absorbed when grapefruit juice was taken. So enjoying your morning grapefruit juice can either increase or decrease levels in the blood depending on the drug prescribed. Orange and apple juice don’t have the same metabolic properties as grapefruit juice, but they still affect the absorption of medication. Dr. Bailey claims that the juice effect on the body lasts for four hours, and patients should consider this time interval when taking drugs. So far researchers at the University of Western Ontario have identified several antibiotics that are affected by these juices such as levofloxacin, ciprofloxacin and itraconazole, and beta-blockers such as atenolol and cellprolol prescribed to treat hypertension. Dr. Bailey suggests that much more work has to be done to determine how many more drugs are affected by grapefruit and other juices. In the meantime, it appears to be prudent that patients should take care that these juices are not consumed with their medication. So with each passing year, life gets more complicated. Now medical consumers have to be concerned not only about adverse reactions between drugs, but also how they react with their morning glass of juice. Hmm, the more I think about it, a martini before dinner seems like a much safer bet.