Reasons for Some to Avoid Grapefruit Juice

[Angel]

It may seem like an unusual health risk, but for nearly 15 years, doctors have warned patients taking certain prescription drugs to avoid drinking grapefruit juice. They knew it could be harmful, but until now, were not sure why. A new study in the American Journal of Clinical Nutrition explains the danger.

For years, doctors believed the danger was caused by flavonoids found in high concentrations in the juice, however studies failed to reveal a connection. Now, researchers from the University of North Carolina at Chapel Hill say a substance in the juice called furanocoumarins is the culprit behind the problems faced by patients on blood pressure or cholesterol medication who drink grapefruit juice. These patients were found to experience undesirable or even dangerous side effects.

The drugs most affected by grapefruit juice generally have trouble entering the body because an enzyme destroys them before they do. Grapefruit juice inhibits the enzyme and allows more medication to enter the body. The problem is that too much of a drug ends up going into the bloodstream.

Study authors, led by Paul Watkins, M.D., worked to create a juice that was free of furanocoumarins. They then compared the whole juice with the altered juice to see what effect each had on the absorption of an anti-hypertension drug known to interact with the juice.

During the study, 18 patients on the drug felodipine took the medication with regular grapefruit juice, orange juice, or the altered grapefruit juice. Blood was collected and analyzed.

Dr. Watkins says removing the one substance got rid of any interaction between the juice and the medication. These findings could potentially lead to the creation and marketing of furanocoumarin-free grapefruit juice for these particular patients. Additionally, researchers suggest this substance could possibly help in the delivery of certain medications that are poorly absorbed by the body.