Healthy Living with Dr. Hall: How Grapefruit Affects Medications

For many grapefruit lovers, the fruit’s distinct taste and health benefits come with a downside: it can cause dangerous interactions with certain prescription drugs. The National Capital Poison Center has found that more than 85 medications, including antidepressants, statins, and antibiotics can have harmful side effects when combined with grapefruit or its juice. However, researchers are investigating ways to genetically modify the fruit to eliminate this issue.

The primary cause of grapefruit’s interference with medications is a class of compounds known as furanocoumarins. These substances inhibit an enzyme called CYP3A4, which plays a crucial role in metabolizing various drugs in the intestines. When this enzyme is blocked, drugs can accumulate in the bloodstream to dangerously high levels, potentially leading to overdose. Conversely, grapefruit can also reduce the effectiveness of some medications, like antihistamines. While other citrus fruits, such as limes and pomelos, also contain furanocoumarins, varieties of oranges (like mandarins and navel oranges) have lower levels of these compounds.

Recent research from Volcani Institute focused on pinpointing the gene responsible for producing furanocoumarins in grapefruit. The hope is that by editing this gene, they can create a version of grapefruit that no longer poses a risk to drug interactions. In their study, the team experimented by crossing grapefruit with mandarin oranges and analyzing the offspring. They discovered that about half of the progeny produced furanocoumarins, while the other half did not. This led them to suspect that one specific gene was responsible for the production of these compounds. Further investigation confirmed their theory.

While other attempts to eliminate furanocoumarins have involved chemical processes or hybrid citrus fruits, such as pomelo-grapefruit crosses, these approaches haven’t been commercially viable due to strict regulations surrounding grapefruit juice labeling. Yoram Eyal, a researcher at the Volcani Institute, emphasized that using genetic editing techniques could allow for the creation of a grapefruit that doesn’t interfere with medications without altering the fruit’s core identity.

Paul Watkins, a drug safety expert, has worked with the Florida citrus industry to explore methods for removing furanocoumarins from grapefruit juice. He found that while the process was effective at reducing drug interactions, it also made the juice lose its distinctive taste. Using genetic tools like CRISPR to remove the gene responsible for furanocoumarin production could offer a more sustainable solution, both in terms of flavor and cost.

The Volcani team is now experimenting with CRISPR to create genetically edited grapefruit that lacks the problematic gene. This process, however, will take several years before it results in fruit-bearing trees. They are also hopeful that, in some countries, this type of gene-edited fruit could be marketed as non-GMO.

Although removing furanocoumarins could potentially reduce some of grapefruit’s antioxidant content, such as vitamin C, researchers believe that other compounds in the fruit can compensate for this. The long-term goal is to develop a grapefruit variety that is safe for medication interactions and widely available for growers and consumers alike.

Dr. David Hall is the owner of Hall Chiropractic Center. With over 40 years of experience, Dr. Hall is proud to serve the residents of Tega Cay and Fort Mill.