Grapefruit, pummelos and beyond

Ordinary grapefruit has chemicals that inhibit the body’s ability to metabolize or break down medications such as statin drugs, which are commonly prescribed for people with high cholesterol.
PHOTO COURTESY OF LS9907/THINKSTOCK

An apple a day keeps the doctor away. However, doctors have been telling the hordes of people on statin drugs to stay away from grapefruit, since it may have an adverse interaction with their medication.

Despite its medical reservations, the UF 914 grapefruit cultivar just might be the solution for people who love grapefruit and grapefruit juice. While UF 914 is still several years from being able to make any human health claims, so far its record in the lab has been quite good – good enough that it’s slowly proceeding to the next levels of research.

Ordinary grapefruit has chemicals that inhibit the body’s ability to metabolize or break down medications such as statin drugs, commonly prescribed for people with high cholesterol. This results in a higher drug concentration in the bloodstream. Drinking traditional grapefruit juice puts the patient at risk. The easiest solution, doctors have found, is to warn patients on statin drugs to avoid grapefruit or grapefruit juice. That’s a disappointment for the 32 million patients who use statins, as well as for the citrus industry. According to the National Center for Health Statistics, one-fourth of all people 45 or older take statins.

In fact, the total number of people warned away from grapefruit is roughly equal to the entire populations of Florida and Illinois combined.

Dr. Fred Gmitter, citrus geneticist at the University of Florida Citrus Research and Education Center in Lake Alfred, Florida stated that with UF 914, the enzymes are turned off. That’s because the three most active problem chemicals in grapefruit juice are either at very low levels or nonexistent in UF 914.

This was proven in a study at Tufts University. There, researchers exposed human liver cells to juice from traditional grapefruit and the UF 914.

“With UF 914, there was virtually no effect on activity,” Gmitter noted. As a bonus, UF 914 is a triploid hybrid, so like triploid bananas and watermelons, it is a seedless fruit. However, Gmitter pointed out, “If growers or commercial companies want to make any health claims for UF 914, we first need human trials.”

Currently, the University of Florida is conducting a small human trial. If the results of that study prove favorable, the next step leads to a much larger, broad-based study. Should UF 914 clear those hurdles, it could go to market with the appropriate health claims, opening up a whole new world of potential fresh grapefruit and grapefruit juice buyers.

One of the reasons UF 914 has not been given a name is speculation concerning major juice firms. Addressing these rumors are often problematic especially with prescription drug users, Gmitter said.

Statins, which are found in atorvastatin (Lipitor), rosuvastatin (Crestor) and simvastatin (Zocor), are often used to lower LDL or “bad” cholesterol.

“Every time there is a story in the press on this, I get all kinds of phone calls,” Gmitter said.

Tangelo-shaped triploid lemon hybrid.
PHOTO COURTESY OF IFAS.

Converting doubters

However, statin users are not the only market with promise for UF 914. Juice and fruit samples from UF 914 were used in a study done by the University of Florida’s Institute of Food and Agricultural Sciences. The two study groups – one who did not like grapefruit and the other who ate grapefruit regularly – were asked for their opinions after trying the cultivar.

When given a sample of UF 914 juice or fruit, the self-professed grapefruit haters became converts. Typical comments showed delight with the sweeter taste of UF 914 when compared to traditional juice. The researchers were overjoyed.

There was concern that the self-described grapefruit fans might decide they didn’t like its somewhat different taste.

As it turns out, there are no worries on that front. People who ordinarily eat tart grapefruit appreciated the fact that they didn’t even feel an urge to put sugar on the UF 914.

UF 914 is one of several cultivars that are part of the Fast Track program coordinated by the New Varieties Development & Management Corp. Maitland, Florida. The program allows growers to test-plant new varieties in their own groves to see how they perform under the groves’ specific soil and climate conditions.

Beyond the usual orange and grapefruit cultivars one might expect, there are some other, less traditional cultivars.

One-fourth of all people over age 45 take statins, according to the National Center for Health Statistics.

The total number of people warned away from grapefruit is roughly equal to the entire populations of Florida and Illinois combined.

The three most active problem chemicals in grapefruit juice are either at very low levels or nonexistent in UF 914.

Before any health claims can be made for UF 914, there must be human trials.

Statin users are not the only market with promise for UF 914.

Pummelo crosses

Crossing grapefruit back with pummelo can produce a range of grapefruit-like selections and others that are very much pummelo.

“We are seeing a wide range of characteristics: shape, size, flavor, colors, disease tolerance, etc.,” said J. Peter Chaires, executive director of NVDMC.

Of the first non-Fast Track selections, one is a grapefruit-like seedless hybrid; one is a grapefruit-sized, low-acid, non-bitter, sweet pummelo; and two are more traditional larger red pummelo types.

Some of the pummelo selections show good huanglongbing (HLB) and canker tolerance. HLB, also known as citrus greening disease, is threatening to wipe out Florida’s citrus industry, so any cultivar that shows resistance to HLB immediately attracts interest. Notable here are the C2-5-12 and Monster lines.

Larger fruit, while attractive to the consumer segment, is not necessarily the best thing when it comes to established packing lines.

Chaires noted that one challenge of the larger pummelos is that they will not run on grapefruit packing equipment. “They would require specialized handling,” he said. There are, however, some grapefruit-sized pummelos that would fit just fine.

The UF 914 grapefruit may allow people using statin drugs to enjoy grapefruit juice again.
PHOTO COURTESY OF IFAS.

A look at lemons, limes

There’s promise in other Fast Track cultivars. At trials, the C4-5-49 lemon has gotten some attention, although it still remains to be seen whether its future is as a niche product or whether it might see wider deployment.

Breeders like Dr. Jude Grosser, University of Florida professor of citrus breeding and genetics, say its future is difficult to predict.

“When someone takes it to Tier 2 [of the Fast Track program], we will get an answer,” Grosser said.

Chaires added that there is much discussion to be had concerning acid fruit types in the breeding program.

The three most active problem chemicals in grapefruit juice are either at very low levels or nonexistent in UF 914.
PHOTO COURTESY OF KOSTMAN/THINKSTOCK

“There is at least enough curiosity among some growers to give them a look,” Chaires said. “We will see some trials of unique lemon and lime selections, but we are a long way off from stating that these will be planted commercially in Florida.”

The likely problem with these lines is not genetics, but marketing. “Some appear to have much greater cold and canker tolerance, which is certainly a benefit, but Florida has not been in these markets for quite some time,” Chaires pointed out.

In the meantime, there has recently been interest in the hybrid limes that IFAS has been working on for some time.

“I expect field trials will be established at two or more locations,” Grosser said.

However, outside of the orange cultivars, it is the grapefruit offering that has generated the most excitement and buzz. Even if it does not gain a label for human health consumption, UF 914 promises to offer the market a sweeter grapefruit juice that consumers love.

Curt Harler, who has a B.S. in agriculture from Penn State University and an M.S. in ag from Ohio State University, is a full-time freelance writer specializing in green topics.