THE SECRET CHEMISTRY THAT MAKES HONEY A SCIENTIFIC WONDER

The benefits of the sweet stuff go well beyond simply nourishing the hardworking insects in the hive.

BERLY MCCOY AND KNOWABLE MAGAZINE
10.30.2021

IT SHOULD COME as no surprise that bees know a lot about honey. They aren’t only honey producers — they are also consumers and pretty sophisticated ones at that. Offer a sick bee different varieties of honey, for example, and it will choose the one that best fights off its infection.

People, on the other hand, have a lot of catching up to do when it comes to the nutritional nuances of honey. Just a few decades ago, most lists of “functional foods” — those that offer health benefits beyond basic nutrition — failed to mention it, says entomologist May Berenbaum. “Even beekeepers — and certainly bee scientists — considered it nothing more than sugar water.”

Since that time, a large body of research has revealed that honey is chock-full of plant chemicals that influence honeybee health. Components in honey can help bees live longer, boost their tolerance to harsh conditions such as intense colds, and heighten their ability to fight off infections and heal wounds. The findings hint at ways to help bees, which have been hit hard in recent years by parasites, pesticide exposure, and habitat loss.

“It’s just such a remarkable substance, and I think people maybe still don’t quite appreciate it,” says Berenbaum, of the University of Illinois at Urbana-Champaign.


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A DIVE INTO THE HIVE — It’s tasty on toast or stirred into tea, but honey is much more than a sweetener. Certainly, the viscous liquid is mostly sugar, which hive members use for sustenance, but it also harbors enzymes, vitamins, minerals, and organic molecules that give each honey its uniqueness and confer a slew of health benefits to bees.

A variety of insects can produce honey — bumblebees, stingless bees, even honey wasps — but only honeybees (Apis species) produce enough to stock grocery store shelves. This ability didn’t happen overnight; it was millions of years in the making.

Bees made the split from wasps around 120 million years ago, during a surge in the evolution and spread of flowering plants. This floral diversity — along with a shift in bee behavior of feeding pollen, rather than insects, to bee larvae — spurred the evolution of the approximately 20,000 bee species known today.

Becoming an expert honey-maker took a few more behavioral and chemical tricks. Bees started adding a bit of nectar to the pollen, which molded it into more transportable bundles. They also developed wax secretion glands, which provided a way to separately store the liquid nectar and solid pollen.

“The wax allows for a very flexible building material,” says Christina Grozinger, an entomologist at Penn State University, who studies mechanisms underlying bee social behavior and health. When forming a honeycomb, honeybees mold wax into hexagons, which turns out to be the most efficient shape to store something, since hexagons pack tightly together. “It’s an engineering feat,” Grozinger says.


A close up of bees ‘n’ honey. Ramlan Jalil / EyeEm/EyeEm/Getty Images

WHY HONEY IS MEDICINE TO BEES

Nectar is what led Berenbaum to honey, an interest that first blossomed in the mid-1990s. She knew that nectar was infused with a ton of plant chemicals, called phytochemicals: compounds that deter pests and help with plant growth and metabolism. She had a hunch that these phytochemicals were coming along for the ride when bees turned nectar into honey. And if they were, she wanted to know what they might be doing for the bees.

So Berenbaum began probing the diversity of chemicals in honey. In 1998, her team found that different kinds of honey contained different levels of antioxidants depending on the honey’s floral origin.

“That piqued my interest,” she says. Her group later found that honeybees fed sugar water mixed with two honey phytochemicals — p-coumaric acid and the potent antioxidant quercetin — tolerated pesticides better than ones that just got the sugar water. On top of that, the bees that received the water laced with phytochemicals lived longer than the bees that did not, she and her colleagues reported in 2017 in Insects.

Other research has unearthed the effects of additional phytochemicals in honey:
Abscisic acid boosts bees’ immune response, improves wound-healing time, and tolerance to cold temperatures, studies show

Other phytochemicals blunt the impact of parasites, one of the major causes of honeybee decline
For example, giving fungus-infected honeybees a syrup containing thymol, a phytochemical from thyme plants, cut the number of fungal spores by more than half
Phytochemicals have even been shown to inhibit the bacteria that cause European and American foulbrood, the latter of which is so devastating and contagious that burning whole hives is recommended to prevent its spread

Some phytochemicals seem to do their stuff by enhancing the activity of genes related to detoxification and immunity. When bees are fed nectar phytochemicals such as anabasine, for example, a gene in charge of making antimicrobial proteins dialed up production, a team reported in 2017 in the Journal of Economic Entomology.

And phytochemicals might confer health by keeping happy the microbial communities that live in and on honeybees: their microbiomes. Caffeine, gallic acid, p-coumaric acid, and kaempferol all improve the diversity and quantity of honeybee gut microbes, researchers reported last year in the Journal of Applied Microbiology. Healthy gut microbiomes in honeybees have been linked to lower intensities of multiple parasitic infections.

Honeybees even choose a health-improving variety of honey when they’re sick. Entomologist Silvio Erler and his team presented parasite-infected honeybees with four honey types. “We simply gave them a choice,” says Erler, now at the Julius Kühn-Institut in Germany. The sick bees preferred sunflower honey, which was also the best medicine for the infection and had the highest antibiotic activity, the team reported in Behavioral Ecology and Sociobiology.

But bees are able to build up their honey pharmacy only if the right flowers are available — not just in numbers and diversity, but throughout the growing season, says Berenbaum, who coauthored an overview of honey’s impact on bee health in the 2021 Annual Review of Entomology. This biodiversity is lacking in the large crop fields that bees are shipped to each year to pollinate staples like almonds, apples, pumpkins, and pears.

Improving the floral diversity does make for healthier bees, says Arathi Seshadri, an entomologist at the United States Department of Agriculture Honey Bee Health Lab in Davis, California. And the USDA incentivizes landowners to convert sections of cropland into wildlife areas through the Conservation Reserve Program. “Agriculture has to go on,” Seshadri says. “But it also has to sustain pollinators.”

Better bee nutrition won’t solve all the problems bees face. But making sure that honeybees have access to their own medicine may help, Erler says. Beekeepers, he suggests, could leave portions of the honey made from various blooms in the hive so that bees have a well-stocked honey pharmacy all year long.

And Berenbaum, who began her investigations years ago because she didn’t think honey was getting nearly enough research respect, says that the accumulating knowledge is a step in the right direction. “I’m glad,” she says, “to see it’s finally attracting some attention.”

This article originally appeared in Knowable Magazine, an independent journalistic endeavor from Annual Reviews. Sign up for the newsletter.