Rich in vitamins, antioxidants, minerals and very low in calories, grapefruit has more than one advantage. And the French have understood this well, since nearly 30% consume it every week and 79% at least once a month, according to a study carried out by researchers at the University of Florida in 2020.
However, this fruit is not without danger. Because consuming pomelos (the real name of the fruit we call grapefruit) while taking certain medications can be toxic. How to explain it? What are the risks ? And the medicines concerned? 20 minutes make the point.
Why is the interaction between grapefruit and certain medications dangerous?
Toxic interactions between grapefruit and certain medications are due to substances called furanocoumarins. “They are mainly found in the white part located under the bark,” explains the Ministry of Health. These agents will neutralize an enzyme, cytochrome P450 3A4 (CYP3A4), which plays an essential role in the breakdown and elimination of certain medications by the body. By eating grapefruit, the quantity of medicine entering the blood will therefore be greater than expected, with a risk of overdose.
“The effects of grapefruit are observed even if it is consumed at a distance from taking the medication: for example, a glass of grapefruit juice drunk in the morning has an effect on a medication taken only in the evening,” specifies the ministry.
These interactions also concern juices. The industrial ones are often made by total pressure of the fruit, they are even richer in furanocoumarins and therefore all the more toxic when taking certain medications.
Be careful, grapefruit is not the only citrus fruit singled out. Bitter oranges, limes, bergamots and tangelos also contain furanocoumarins under their peel.
What are the dangers ?
Due to overdose, there is a risk of increased adverse effects of the medication. Among others: heart rhythm disorders, muscle disorders, toxicity to the kidneys, bone marrow and blood clots.
“Elderly people are particularly at risk because they consume more medications and have more associated weakening pathologies, such as heart diseases,” adds Jérôme Barrière, a medical oncologist who has warned of these risks of interaction with X.
What medications are affected?
Multiple substances are at risk of overdose. Cholesterol medications such as simvastatin (Zocor, Lodales) or atorvastatin (Tahor), for example, increase the risk of muscle damage. Immunosuppressants such as cyclosporin (Neoral) and tacrolimus (Prograf), antiarrhythmics such as multaq and procoralan, anti-inflammatories such as budesonide. The antidepressant sertraline, better known as Zoloft, the anxiolytic buspirone and the antipsychotic quetiapine are also affected. “On the other hand, no relationship between the consumption of grapefruit juice and a reduction in the effectiveness of antibiotic or contraceptive treatment has been established,” adds the agency.
If in doubt, do not hesitate to ask your doctor or pharmacist who, unlike the general public, are in the know. “The instruction, if you take one of these treatments, is not to consume grapefruit,” says the oncologist. A glass of water is good too.