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Drinking fruit juice 'may stop medication working'
Last updated at 00:39am on 20.08.08
Refreshing: But is it wiping out the benefits of prescription drugs?
Drinking fruit juice dramatically reduces the effectiveness of drugs used to treat cancer, heart conditions and high blood pressure, scientists say.
Research has shown that orange, apple and grapefruit juice can also wipe out the benefits of some antibiotics and hay-fever pills.
It is thought the drinks stop drugs from entering the bloodstream and getting to work in the body - possibly rendering them useless.
The potential effects are so serious, researchers warned, that if in doubt, patients should swap fruit juices for water when on medication.
Researcher David Bailey said: 'This is just the tip of the iceberg. I'm sure we'll find more and more drugs that are affected this way.'
Twenty years ago, Professor Bailey showed that grapefruit juice dangerously magnifies the effect of the blood pressure drug felodipine.
His findings led to warnings that the drink should be avoided by those on some medicines.
The latest study shows that fruit juices can also reduce the power of medicines - potentially stopping them from doing any good.
Professor Bailey, of the University of Western Ontario, in Canada, said: 'The concern is loss of benefit of medications essential for the treatment of serious medications.'
Drugs shown to be weakened by grapefruit, orange and apple juices include the blood pressure-lowering beta blockers atenolol, celiprolol, and talinolol and the hay-fever treatment fexofenadine.
The multi-purpose antibiotic ciprofloxacin, used to combat germs behind food poisoning and bone and joint infections, is also affected.
So is the cancer drug etoposide and a drug given to prevent the rejection of transplanted organs.
Many other drugs are also likely to be affected, an American Chemical Society conference heard yesterday.
The study showed juices do not need to be taken at the same time as drugs to have a dangerous effect.
Those drunk up to two hours before can reduce drug absorption.
But patients need not stop drinking juice altogether.
Professor Bailey said: 'Juice taken four hours prior to drug intake did not have an effect. Thus, it should be possible still to take grapefruit, orange and apple juices while on affected medications provided there is a sufficient time interval.
'I would recommend taking drugs with water on an empty stomach to get the most consistent effect.'
The researcher, a professor of pharmacology, advised patients to speak to their doctor or pharmacist before taking fruit juice with medicines.
Professor Bailey made the link after asking volunteers to take the hay fever drug fexofenadine at the same time as either a glass of water or grapefruit juice.
Taking it with juice cut its absorption into the bloodstream by half.
Experiments showed naringin, the chemical which makes grapefruit taste bitter, blocked the drug from moving from the small intestine into the bloodstream.
The researchers have pinpointed a naringin-like compound in orange juice and are looking for a similar one in apples.
A different mechanism is at play with the drugs whose levels are boosted by grapefruit juice.
There, juice deactivates a liver enzyme that breaks down drugs, making normal doses potential overdoses.
The study is not the first to highlight the dangers behind supposedly healthy juices.
Last month, research from Harvard Medical School in the U.S., showed that one glass of orange juice a day can increase the risk of a form of diabetes linked to poor diet and obesity.
But eating whole pieces of fruit cuts the likelihood of developing the disease. It is thought the lack of fibre in juices may cause spikes in blood sugar levels.
Reader views (13)
I've been taking atenolol for years and this is the first time I've heard that I should not be driniking orange juice within four hours (before or after) of taking this medication. Thank you for alerting me to this problem!!!
- Ken Souza, New Bedford, MA USA
In my experience orange juice, or any kind of citrus, makes adderral stop working. From what I've read its something to do with ascorbic acid.
- Ali, MA
I take a medication called Diltiazem, recently it was changed over because it caused me to experience bad headaches. My doctor chaged it to another high blood pressure medicine but recently instead of taking the new medication I took the old one and began to panic, so I took and began to imediately drinkl lots of water to flush out the medicine in my system and it helped! Ms B
- Angela Marie Byrd, United States
I wash my morning calcium pill down with orange juice, each day, and have been for years. I was told, recently, by a nurse friend, that I should not be doing this. I have not been able to find out any answers, to this problem, via the internet. Can you help?
- Virginia, Natick, MA, USA
I thoroughly enjoyed this article. I learned that there are potentially two mechanisms at play here. One, juice can possibly reduce the amount of medication absorbed. Two, grapejuice can possibly reduce the liver's ability to breakdown certain medications, leading to 'overdoses.'
- Austin Lee, San Francisco, CA; USA
@James-
No, grapefruit juice reduces the amount of the enzyme Cytochrome P450 3A4, which is important in the pathway for metabolizing xenobiotics.
- Griffy, PA, USA
to Freezem:
this just states that the liver is overwhelmed, the livers chemicals break down everything we put into our bodies, many compounds are dissolved by the same chemicals.
We are just now scratching the surface of how our livers and brains work, they probably are strangely similar. any recent research in these fields should not be taken lightly.
- James Holden, Florence, AL, USA
Interesting article - I currently take the beta-bloca = cardevilol and although not a regular fruit juice imbiber I do have orange juice binges and must admit I have noticed an unwell feeling - I have always put this down to the aetrial fibrillation in my condition - I will stop juices completely as I believe in doing everything that can help.
- David Moore, glynneath wales
How new is this research? My pill bottle of fexofenadine has advised against taking the pills with orange juice for a year or two.
- Ryan, Louisville, KY
So drinking orange juice might prevent chemicals from entering the bloodstream. This is great news! Everybody NOT on medication should drink orange juice so they can help prevent ever needing medication. Right? Why is it that the focus is on the possible 'bad' effect on medication, not on the possibly great effects on health. Was the research funded by the pharmaceutical industry maybe?
- Freezem, Maasland, Netherlands
Well, perhaps taking meds with water on an empty stomach will yield "the most consistent effect" in a literal sense. But that effect may be consistently poor due to the empty stomach!
There are many drugs which are actually better absorbed with food, or in an acidic environment. Also, many drugs will irritate the digestive tract unless taken with food!
I'd say for best results read the information sheet that comes with the medicine.
Also if you're taking any calcium or magnesium supplements, avoid taking those at the same time as any medicines... since these minerals can bind with drugs and prevent absorption.
- Doug Brenner, Minneapolis, USA
If scientist say this, name them. If you can't, don't spread unsubstantiated rumours.
- Vicente Aceituno, Madrid, Spain
This is very important news but the drinking fresh juice has its on importance.
- John, Pakistan
