Grapefruit Interactions with Medication and Your Liver

Filed Under: Food and Nutrition
Last Reviewed 02/18/2014

The liver can be literally overwhelmed metabolizing grapefruit. It does so via the P450 pathway—the same metabolic superhighway your body uses to break down and absorb many common drugs. 

While we don’t know for sure why our livers make grapefruit metabolism such a high priority, the result is that medications are not absorbed effectively, so they can either be rendered less effective or accumulate. And that brings up another problem—as I indicated last week, a drug affected by grapefruit interactions can either be poorly absorbed or reach toxic levels. And I can only imagine how impairment of one medication may impact the absorption or possible side effects from yet another you may be taking!

Additionally, the signs of a problem may be insidious and subtle. For instance, someone taking an antidepressant may have too much or too little energy, depending on the specific drug and grapefruit interactions. Someone pumping vitamin C levels with grapefruit to fight an infection make take longer to improve despite the antibiotic they are taking—or develop diarrhea. 

Grapefruit Interactions in Women

According to a recent British study, postmenopausal women eating half a fresh grapefruit daily were 30 percent more likely to develop breast cancer than those not consuming the fruit. And we know that even HRT can be affected by grapefruit. One speculation is that the grapefruit interactions in the body may directly increase estrogen levels

Grapefruit Interactions in Men

Dr Sinatra has also cautioned men that grapefruit augments the body’s production of aromatase, an enzyme that converts testosterone to estrogen in men, often causing an undesirable feminizing effect. In fact, he took a dietary history on one of his male patients who complained of erectile dysfunction (ED). When he learned the gentleman ate or drank grapefruit/grapefruit juice every day, Dr. Sinatra advised him to stop immediately. As a result, the ED resolved in just a few weeks.

So, remember Dr. Sinatra’s advice to enjoy grapefruit and grapefruit juice on occasion to be on the safe side … and not at all if you take medication.

For more information on Dr. Sinatra, visit

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