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Fruit and Pill Make Potentially deadly Mix

Posted on 02 April 2009 by admin

A strange interaction between grapefruit and birth control pill may have cause of a blood clot.

An American woman in her 40s nearly lost a leg to gangrene because of a confluence of health factors exacerbated by a diet that included daily doses of grapefruit, the doctors who treated her reported in a medical journal on Friday.

“The way I think of it actually is like she’s a setup for the perfect storm. And I believe it was the grapefruit that tipped the balance,” Dr. Lucinda Grande, a medical resident at Providence St. Peter Hospital in Olympia, Wa., explained in an interview.

Grande is the first author on the case report, which appears in this week’s issue of The Lancet.

The woman, then 42, arrived at the hospital’s emergency room last November with a badly swollen and discoloured left leg. She was experiencing shortness of breath and light-headedness.

Doctors diagnosed a large deep vein thrombosis – a dangerous blood clot – in her left leg, running all the way from her hip to her calf. Because of the condition of the leg, the doctors treating her were worried she might be developing irreversible gangrene that would force amputation of the limb.

But quick treatment with clot-busting drugs and the insertion of a stent to open a chronic narrowing of a large vein in her hip resolved the problem and saved the leg.


In addition to having this congenitally narrow vein in her left hip, the woman was slightly overweight, took oral contraceptives and had driven for an extended period, about 1.5 hours, the day before the problem occurred.

All of those factors individually increased her risk of developing a blood clot, the authors said. And together they raised the risk even more.

But when Grande was discharging the woman from hospital, the patient mentioned she’d started a diet three days before that involved eating 225 grams of grapefruit every morning. She had rarely eaten grapefruit previous to that and wondered if it might be playing a role.

The doctors consulted the medical literature on the multiple drugs grapefruit interacts with and concluded that it’s likely the grapefruit was the straw that broke the camel’s back in this particular case.

They do not, however, believe others should change their grapefruit consumption patterns based on this case.

“I think … this woman’s story is so unique it should not discourage people in any way from eating grapefruit,” Grande said.

“Grapefruit is not a danger to society. It just happened to be dangerous for this specific person in this specific situation.”

It’s been known for nearly 20 years that grapefruit can trigger serious interactions with drugs. The person who first spotted the problem is Canadian pharmacologist David Bailey, who teaches at the University of Western Ontario.

Bailey was trying to devise a study to see whether alcohol would interact negatively with felodapine, a commonly prescribed drug for high blood pressure. He wanted to make sure the trial was blinded, meaning neither the doctors nor the volunteers would know who was drinking alcohol.

The only way he could find to effectively mask the flavour of the alcohol was to mix it with grapefruit juice. The wonky results he got made him look further, leading to the discovery that grapefruit and grapefruit juice block the ability of the small intestine to break down some drugs.

The result is like an unintentional drug overdose for medications with which grapefruit interacts, Bailey said from London, Ont.

Since Bailey first reported the finding in The Lancet in 1991, more than 55 drugs have been found to interact with grapefruit. Included among them are some statins (cholesterol lowering drugs), some antihistamines, and some drugs used to treat arrhymias or irregular heartbeats.

The authors of this case report said the grapefruit the woman consumed blocked the breakdown of the estrogen in her birth control pills. Estrogen increases the risk of blood clots.

Bailey said the effect of grapefruit on estrogen is not generally large, but in this particular case build up of additional estrogen may have been enough to cause the problem.

“I don’t think on the whole it’s a huge problem….But it may be enough to tip her over the balance,” he said.

Florida’s Department of Citrus disagreed, issuing a statement Thursday disputing the hypothesis.

“We are aware of no validated evidence that grapefruit affects oral contraceptives, and they are generally considered to be safe to consume with grapefruit,” it read.

Bailey said some other citrus fruits also interact with drugs in the same way, including limes, Seville oranges (but not navel oranges) and pomelos.

The Canadian Press

1 Comments For This Post

  1. Cindy Says:

    I know this is really boring and you are skipping to the next comment, but I just wanted to throw you a big thanks, you cleared up some things for me!

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