Tart and tangy, fresh grapefruit juice can be a delicious and nutritious way to jump-start your day. The nutrients in grapefruit make it a powerhouse and experts claim adding a few squeezes to your diet has health benefits including: immune-supporting doses of vitamin C, heart-healthy dietary fiber, cancer-fighting phytonutrients, and cholesterol-lowering pectin. It's also known to suppress the appetite, prevent kidney stones and protect against colon cancer.

If you didn't know better, you might just consider grapefruit juice the ultimate health food-or at least the greatest news since antioxidants were found in dark chocolate!

Unfortunately, there's a downside. In 1991, Canadian researcher Dr. David Bailey discovered a problem. While researching the effects of alcohol on the blood he learned-quite by accident-that grapefruit juice could have a detrimental effect on the efficacy of certain drugs. 

Known as the "grapefruit juice effect," Bailey's discovery showed that when the citrus juice comes in contact with an enzyme (CYP 3A4) found in the intestines it has the ability to turn a normal dose of medicine into a toxic overdose. Taken with grapefruit juice, for example Valium for back or neck pain can be life threatening.

In other cases, the beverage can reduce the effectiveness of certain meds. So a heart patient might not get the lowered blood pressure a medication should deliver. The effect can occur in medications taken orally, but not with medications given intravenously.

Why Grapefruit Juice Effect Is Still a Problem

There are a few reasons why the interaction still occurs. One, is that people older than 45 buy the most grapefruit and not surprisingly take the most prescription drugs. Compounding the problem is that older adults tend to be less able to compensate when faced with excessive concentrations of drugs compared to young and middle age patients.

The other big issue is that there are more drugs on the market with potentially dangerous side effects when combined with grapefruit juice. The list now includes 85 medications, according to a recent article in The New York Times (Bailey's original list has 44 dugs on it.)

These drugs are used to treat high cholesterol (Lipitor), depression (Prozac), and pain (Oxycodone and Valium). New anti-cancer agents, certain immunosuppressant meds taken by organ transplant patients, AIDS' medications, some birth control pills and estrogen treatments also may interact with grapefruit juice.

In the two decades since the problem was uncovered Mattison says it has been well publicized. "Most doctors and pharmacists are aware of it. However, breakdowns in communication can still occur," she says explaining a scenario in which a relative or friend picks up a new prescription and the information doesn't get translated or pharmaceutical counseling is offered but denied." Today, many hospitals have stopped serving grapefruit juice altogether to minimize risk, she adds.

What You Can Do to Lower Risk of an Interaction

Timing the consumption of citrus juice doesn't seem to lower risk. So having a little bit of juice in the a.m. may still interfere with the medicine you take in the p.m. "The interaction can be unpredictable," says Melissa Mattison, Pharm D, clinical assistant professor of community care at the College of Pharmacy at Western New England University in Massachusetts. "To be safe, avoid eating even a small section of fresh grapefruit as well as a few ounces of grapefruit juice."

In some cases, though, there are a few alternate medications (some with generic versions) that aren't impacted by grapefruit juice. "A patient with heart disease who really loves grapefruit may be able to take pravastatin, a generic med that isn't affected by grapefruit," the pharmacist says adding with some classes of medication, it's not always that easy.

Experts say statins are especially problematic as the combination can lead to a dangerous build-up in statin levels that may trigger a rare but serious disease called rhabdomyolysis. "If you experience muscle pain, call your doctor right away. Within 48 to 76 hours of ending grapefruit juice consumption the body can remedy the problem," the pharmacist explains.

Still can't live without citrus? The good news is you don't have to give up citrus altogether since some doesn't interact with medication. "Lemons are generally okay and most oranges—with the exception of the Seville, or sour orange," she says adding that if you take one of the listed drugs on a regular basis you'll also want to avoid pomelos, limes and marmalade since Seville oranges are used to make the chunky concoction.

Fortunately there are other tasty ways to get the health benefits of antioxidants into your diet. Green tea, for instance is full of antioxidants. Almonds and dried apricots are wonderful snacks and for vitamin C eat more spinach, broccoli, strawberries and tomatoes.

For a full list of medicines that react with grapefruit visit: www.cmaj.ca/content/suppl/2012/11/26/cmaj.120951.DC1/grape-bailey-1-at.pdf

(Note: For 43 of the drugs on the list consumption with grapefruit juice can be life-threatening. Many are linked to an increased heart rhythm that can lead to sudden death. Other problems are: acute kidney failure, respiratory failure, gastrointestinal bleeding and bone marrow suppression in people with weakened immune systems death.)

Melissa Mattison reviewed this article.



Interview with Melissa Mattison, Pharm D, clinical assistant professor of community care at the College of Pharmacy at Western New England University in Springfield, Mass.  

The New York Times

National Institute of Health