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Grapefruit juice can make cancer drug three times more effective

Grapefruit juice increases the absorption of a cancer drug into the bloodstream, says a new study. (Thinkstock …It appears that grapefruit juice is packing a punch in the world of medicine.

This humble fruit has been proven to strongly affect various medications, and now, recent research shows it has a significant effect on the anti-cancer drug, sirolumus.

Grapefruit juice when combined with sirolumus has been shown to make the drug three times more effective, suggests a new study published in the journal Clinical Cancer Research.

"Sirolimus was the first of a series of drugs...developed to prevent the rejection of transplanted organs,  but also have anti-cancer effects," reports UChicago News.

Grapefruit juice works by blocking an enzyme that breaks down the sirolumus. As a result, it increases the absorption of sirolumus into the blood stream.

Researchers at the University of Chicago discovered that patients who drank grapefruit juice had their blood levels of sirolimus rise by 350 per cent.

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While it's premature to advise cancer patients to supplement drugs with grapefruit juice, researchers found that the increased uptake of the potent drug allowed their test patients to cut their drug dosage by one third.

"The lower dose meant that patients had far fewer side effects from the drug. If this same mechanism can work on similar drugs — something the researchers say is hopeful — doctors could prescribe other medications at lower doses, reducing side effects and saving money," LiveScience reports.

While this is the first study to look at the affects of grapefruit on the drug sirolimus, it is not the first for other medications.

Some blood pressure medications are recognized as dangerous when taken with grapefruit juice — and some medications have been proven less effective when taken with the juice. See WebMD's list of medications here.

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Furanocoumarins in grapefruit juice can boost the effect of many blood-pressure and anti-anxiety medications, risking overdose.

"With the enzymes blocked, these drugs move more quickly and freely into the bloodstream and can spike the body with dangerous and even toxic levels of the medication," reports LiveScience.

"As little as one glass of grapefruit juice (8 oz. or 250 mL) can cause an increased blood drug level and the effects can last for three days or more. Therefore, even if you drink the juice in the morning and do not take your medication until bedtime, the level of the drug in your blood could still be affected," Health Canada cautions.

Birth control pills are affected by grapefruit juice in a similar manner. The juice affects the breakdown of the drug in your system, thereby increasing your estrogen levels. And increased estrogen levels may up your risk of blood clots.

Once specific case study reported by the Toronto Star in 2009 mentions a woman who was admitted to hospital with a blood clot. The doctors who treated her later reported in the Lancet medical journal that the high grapefruit diet she was on, combined with the birth control pills she was taking, likely contributed to her blood clot.

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