A small red berry known as “miracle fruit” is drawing growing interest for its unusual ability to turn sour flavors sweet, and for offering relief to cancer patients struggling with a common side effect of chemotherapy.

Many patients undergoing treatment experience “chemo mouth,” a condition that causes food to taste metallic, bland, or spoiled. This can lead to reduced appetite, weight loss, and poor nutrition.

The fruit, scientifically called Synsepalum dulcificum, is now being explored as a way to help patients better tolerate food and regain a sense of normal eating.

“A lot of side effects from cancer treatments are underreported,” Dr. Mike Cusnir, a board-certified oncologist and co-director of gastrointestinal malignancies at Mount Sinai Medical Center in Miami Beach, Florida told the New York Post on Monday.

He explained that taste disruption can worsen over time and significantly affect a patient’s well-being.

“The alteration in taste will end up giving the patient the sensation that everything is absolutely bland,” Cusnir said.

“And we may think that that’s negligible, that it’s not that important — but with time it becomes bothersome to the point where the patient doesn’t eat, then there’s weight loss.”

While the severity varies, the consequences can be serious. Poor nutrition and weight loss may interfere with ongoing cancer treatment, he noted.

In his research, Cusnir found that common strategies — such as switching utensils, adjusting food temperature, or adding spices — often fail to provide meaningful relief.

He first encountered miracle fruit when a patient introduced it to him, demonstrating its effects with a lemon.

“I’m like, ‘That’s going to be tangy,’” Cusnir recalled. “He’s like, ‘OK, try it.’ So I tried it. It was tangy. Then he said, ‘Now, try the fruit and then squeeze it again.’ And it tasted like lemonade.”

The berry contains a compound called miraculin, which temporarily alters taste perception. Its effects typically last between 30 and 40 minutes, though researchers are still studying how it works and why results differ among individuals.

In a small clinical study, about half of the patients who used the fruit reported improved taste and overall quality of life, while 14% experienced weight gain.

However, the fruit was not effective for everyone, and experts caution that the findings are still preliminary.

Memorial Sloan Kettering Cancer Center notes that while some small studies suggest potential benefits, the overall evidence remains limited and inconsistent.

More comprehensive research is needed to determine how effective the fruit truly is and which patients are most likely to benefit.

Because the berry is delicate, it is often sold frozen or in tablet or powder form, as it can quickly lose potency after being harvested. Availability has increased in recent years, though product quality may vary.

Cusnir said there have been no clear safety concerns observed so far, and there is no strong evidence that the fruit interferes with cancer treatments. Still, patients are advised to consult their doctors before trying it.

Researchers are also exploring whether the fruit could help people with diabetes by making low-sugar foods more appealing.

For patients dealing with taste changes, even small improvements can make a meaningful difference in daily life.

“If a meal becomes a challenge for the patient, and they just don’t want to be there because they’re bothered by the food, they may isolate,” Cusnir said.

He added that this isolation can deepen the emotional toll of cancer treatment.

“Patients are tired, fatigued, and the time they spend with their family — if food is bothering them — it creates more isolation,” he said.

Helping patients enjoy even part of a meal again can have a significant impact, he said.

“Patients are with us maybe 15 minutes every few weeks,” Cusnir said.

“But they’re at home, with their family, three meals a day.”