Sliding a mesh screen door, Erik Tietig points to rows of plants that have been his focus for the past decade. Standing nearly 2 m tall in plastic pots and sheltered by shade cloth, the Synsepalum dulcificum shrubs native to West Africa grow well in Florida’s subtropical climate. The varieties grown at Tietig’ s 2.4-hectare farm—about 30 km outside Miami—produce berries all year round.
But they’re no ordinary berries.
Roughly the size of a peanut and bright red in color, with a mild, cherrylike flavor, the fruit can temporarily alter taste. The berry’s fleshy pulp contains a glycoprotein called miraculin that binds to human sweet-taste receptors, making sour foods taste sweet. The sweet-taste receptors become activated only in the presence of acidic foods. “The effect is immediate,” Tietig says. “It’s undeniable and unmistakable.”
In the US, these so-called miracle berries have been the star of flavor-tripping parties. Guests eat the berry’s edible portion, spit out the seed, and then try a range of foods. For the next 15 to 30 min, lemons taste like lemonade, vinegars are less acidic on the palate, and hot sauce tastes like sweet chili sauce.
But it’s not just people in search of a novel gustatory experience that seek out miracle berries. People with cancer are also tracking them down to benefit from the fruits’ taste-modifying effect.
In parts of West Africa, where the plants are native, locals use the berries as sweeteners. They often consume the fruits, known by various names in the region, including asaa, sisrè, tanté, and ledidi, before drinking a palm wine that is sour and slightly bitter tasting, says Margaret Sraku-Lartey, who documents Indigenous peoples’ knowledge of forests at the Council of Scientific and Industrial Research–Forestry Research Institute of Ghana. Children also enjoy the berries. “They just put it in the mouth and then go for some nice tangerines or oranges,” she says.
While the fruit’s taste-altering effect is long-standing Indigenous knowledge, European explorers learned about the phenomenon from local users in the 1700s. American botanist David Fairchild first encountered the berries on a trip to Cameroon in the early 1900s and imported the species to the US.
Several early attempts in the 1920s and ’30s to cultivate the plant at the US Department of Agriculture’s Plant Introduction Station in Miami failed. Southern Florida’s limestone-based alkaline soils weren’t conducive to the plants’ growth and survival. A decade or so later, William Whitman, a self-taught horticulturist and founder of the Miami-based nonprofit Rare Fruit Council International, grew them successfully in slightly acidic soils.
Soon enough, nurseries in the state began to propagate and sell the plants and seeds. Pine Island Nursery, owned by Tietig’s mother, Colleen Boggs, was among them. “It was a cool little thing that became part of the catalog in the 1970s,” he says. “Nothing mainstream.”
But sales picked up in the early 2000s, when Tietig added a note on the nursery’s website about how the berries had helped mask the metallic taste that one of his customers experienced while being treated with chemotherapy.
“We would get multiple calls daily, multiple visitors daily,” he says. Emails requesting the plants and fruits came from Canada, Latin America, and western Europe, as well as within the US. “We felt there was a real opportunity for somebody to try and grow this fruit commercially,” Tietig says. And so Miracle Fruit Farm was born in 2012.
People undergoing chemotherapy and radiation therapy often experience taste changes. The treatments can damage taste buds and reduce saliva production, which is key to tasting food flavors. Bitter-tasting cancer drugs can also enter the saliva and lead to the development of a “metal mouth.”
Food may seem to lack flavor or taste more salty, bitter, or metallic. “It’s one of those side effects that’s been really hard to address,” says Jessica Chew, a radiation oncologist at the University of California, San Francisco. In addition to having a dry mouth and mouth sores, which makes eating difficult, a patient may experience reduced appetite because of an altered sense of taste. “It can be very detrimental for the patient,” she says.
To improve taste dysfunction, Chew and others have been trying to determine if the miracle berries can help. Through clinical trials, they’ve been assessing whether the fruits could benefit people undergoing cancer treatment by increasing their food intake, weight, nutritional status, and quality of life.
In 2008 and 2009, Mike Cusnir, an oncologist at Mount Sinai Medical Center in Miami Beach, and his colleagues conducted a study that included a total of 23 people with breast, colon, or other cancer. Over 2 weeks, the trial participants ate a freeze-dried miracle berry before every meal while they underwent chemotherapy.
In questionnaire surveys, 7 people out of the 23 reported improvements in taste perception, but that didn’t result in significant weight gain (J. Clin. Oncol. 2010, DOI: 10.1200/jco.2010.28.15_suppl.e19523). Because of the variations in the types of cancer and chemotherapy, and in the number of chemotherapy cycles a person may have undergone before participating in the study, it was hard to draw conclusions, Cusnir says. His team also didn’t account for differences in individuals’ diets.
In a 2012 study, researchers at Creighton University in Nebraska provided miracle berries to eight people who had reported taste changes while being treated with chemotherapy. After 2 weeks of consuming the fruit, all participants reported taste improvements, and five described the disappearance of the metallic taste they were experiencing during chemotherapy (Clin. J. Oncol. Nurs. 2012, DOI: 10.1188/12.CJON.E173-E177).
Another trial recently conducted in Spain tested different doses of the miracle fruit among people who were undergoing chemotherapy or both chemotherapy and radiation therapy. Chew and her colleagues are currently recruiting 40 people who are receiving radiation therapy for head and neck cancer and who will consume the berries—in freeze-dried cube form—for 7 weeks.
It’s unclear whether these new clinical trials can control for the variations in individuals’ cancer treatments and diets. But “whether our trial ends up returning positive results or not, we’re still hoping to also learn a lot more about radiation’s effects on taste,” Chew says.
Meanwhile, people with cancer who have heard about the berries through word of mouth or from their oncology nutritionists have been using the fruits outside these trials.
Some who’ve taken the berries experience benefits, others don’t, and a few encounter side effects such as stomachache, nausea, or vomiting. But “the side effects are pretty minimal,” Chew says, “since it’s a very temporary effect and it doesn’t cause any systemic symptoms that we know of.”
Still, for clinicians to make sound recommendations, large clinical trials are needed to understand which people have taste improvements from consuming the berries and why, Cusnir says.
For now, Tietig is awaiting the results of Chew’s study, given that his farm provided the freeze-dried berry cubes for the research.
While Tietig and other growers also sell the plants and fresh berries, the fruits perish quickly. “They last for a couple of days or so once harvested, and the miraculin begins to break down almost immediately after harvest,” he says. That’s why the freeze-dried berry cubes are popular, Tietig adds.
To prepare the cubes, the staff at Tietig’s farm harvest berries four times every week. Then, in an on-site food laboratory, they separate the pulp from the seed. This pulp is freeze-dried and turned into a powder, which is sold as is or compressed into cubes resembling the sort you might drop into a hot cup of tea.
These cubes melt on the tongue. A pack of 15 cubes costs about $25, which Tietig sells via the company’s website and at the Miami Cancer Institute’s pharmacy. Other companies also produce and sell similar cubes at various price points.
In the US, it’s legal to sell these berries whole or in powdered form. But the US Food and Drug Administration lists miraculin as a food additive, and it currently doesn’t have generally recognized as safe (GRAS) status. However, in response to a GRAS notice Tietig submitted to the FDA, the agency recently affirmed the use of miracle fruit powder in water-based beverages such as sweetened or flavored bottled waters (excluding soft drinks, sports drinks, and energy drinks), coconut water, and sugar cane beverages. In the European Union, dried miracle berries have been approved as a “novel food.”
Tietig says there is growing interest from beverage companies looking for sugar alternatives. That’s a market he is exploring, but his primary focus remains trying to help people with cancer, he says. As research continues, there’s still need for large clinical trials to determine the true extent of the miracle fruit’s effectiveness for people with cancer, as Cusnir says.