The “grapefruit diet” almost proved fatal for a 42-year-old woman who was on the birth control pill, according to a study published in the British medical journal The Lancet.

The woman, from Olympia, Wash., had been on the grapefruit diet for only three days, researchers say the combination of excessive grapefruit consumption and the birth control pill caused her leg to become gangrenous. She almost lost the leg.

The diet plan calls for replacing some meals with grapefruit, which is known for its fat-burning properties. But it can also block production of an enzyme that breaks down drugs. And with no release for the medication, dangerous blood clots can form, causing heart attacks, strokes or gangrene, according to the study.

Researchers, Dr. Lucinda Grande and Raul Mendez said this woman’s high consumption of grapefruit had stopped a key enzyme from breaking down the hormone estrogen.

“Her three days of grapefruit for breakfast may well have tipped the balance,” the researchers added.

Patients who take anti-cholesterol drug Zocor are also warned against eating grapefruit and drinking its juice after studies showed its efficiency can be inhibited.

Click here to read more on this study from The Lancet (subscription required).

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