By Dani Cooper
If you are about to take your daily dose of medicine with a salad replete with pomegranate seeds and juice, then think again.
Consuming the exotic fruit as a food, juice or extract in herbal medicines can interfere with the body’s uptake of pharmaceutical drugs, an Australian study has found.
The finding underscores the complex relationship between pharmaceutical drugs and food, says co-author Dr Fanfan Zhou, from the Faculty of Pharmacy at the University of Sydney.
And it highlights the need for further research into the interactions between drugs and foods, she believes.
The study, published in the journal, Pharmaceutical Biology , looks at how the three major active components in pomegranate interfere with the delivery of drugs via proteins known as solute carrier transporters.
Solute carrier transporters play a key role in helping substances or molecules such as hormones move across biological membranes and are known to play key roles in drug absorption and distribution, says Zhou.
They also play vital roles in the elimination of toxic molecules by helping transport toxins to the liver and kidney where they can be eliminated from the body.
Zhou says the research team focused on the impact of pomegranate on drug transport as it contains three components — oleanolic acid, ursolic acid, and gallic acid — that are commonly found in other foods.
Oleanolic and ursolic acid are widely found in plants; while gallic acid is found abundantly in tea, grapes, different berries, fruits, as well as wine.
Pomegranate is also widely consumed in herbal medicines as it is known to have anti-inflammatory and antioxidant effects.
More recently scientific studies have also shown pomegranate to have potential antidiabetic properties.
However, co-administration of these three compounds with other drugs have been reported to be problematic possibly due to drug and food interactions, which lead to altered performance of the drugs in body.
“Our study confirms the three pomegranate components can impact on these transporters, which means if there are other drug molecules going into the cells through these transporters, then the presence of those pomegranate components is going to interfere with the drugs,” says Zhou.
The most likely impact is that it will inhibit the drug molecules from going into the cells as they are competing with the pomegranate components for the same transporters, she adds.
Zhou says a wide range of drugs are transported into the body by solute carrier transporters. These include a number of statins used to treat heart disease and anti-cancer drugs such as paclitaxel and methotrexate.
Food and drug interactions
Zhou says it is the first study of its kind to widely show the interactions of the pomegranate components with the set of solute carrier transporters and will have a significant impact on drugs used together with certain foods or herbs, such as natural medicines and Chinese herbal medicines.
“It doesn’t matter if you drink the juice or eat the real fruit, these three components stay the same.
“So our study will have a wider application than just herbal medicines made from pomegranate,” says Zhou.
The research also suggests that any food or herb extract — not just pomegranate –that contains those compounds could be an issue.
“We want to warn people that when they are taking particular drugs they need to find out if this drug will be affected by other foods or medicines consumed at the same time.”
Zhou says users of Chinese medicines in particular need to be aware that traditional medicines can impact on pharmaceutical medicines.
“In Asian countries people do like taking prescription medicines with herbal medicines. And they don’t even know there is a potential risk in co-administration of drugs,” she says.