On Meds? You May Be Able to Eat Grapefruit Again Someday.
The New York Times
Scientists have identified a gene that causes production of a substance in some citrus that interferes with many medications.
You may be among the millions of people who have seen a surprisingly specific warning like this on the labels of drugs you take:
Avoid eating grapefruit or drinking grapefruit juice while using this medication.
Such warnings are issued for dozens of substances, including docetaxel, a cancer drug; erythromycin, an antibiotic; and some statins, the cholesterol-lowering drugs prescribed to more than a third of American adults over 40.
The problem is a set of molecules, furanocoumarins. High levels of furanocoumarins interfere with human liver enzymes, among other processes. In their presence, medications can build up to unhealthy levels in the body. And grapefruits and some related citrus fruits are full of them.
But there is no such warning for other kinds of citrus, such as mandarins and other oranges. Citrus researchers at the Volcani Center in Israel reported Wednesday in the journal The New Phytologist that, by crossing mandarins and grapefruit, they’ve uncovered genes that produce furanocoumarins in some citrus fruits. It’s a finding that opens the possibility of creating grapefruit that doesn’t require a warning label.
Scientists had worked out the compounds’ structures and pieced together a basic flowchart of how they are made years ago, said Yoram Eyal, a professor at the Volcani Center. But the precise identities of enzymes catalyzing the process — the proteins that snip off a branch here, or add a piece there — remained mysterious. He and his colleagues knew that one way to identify them was to breed citrus high in furanocoumarins with those without. If the offspring of such a cross had varying levels of the substances, it should be possible, by digging into their genetics, to pinpoint the genes for the proteins.
