Beehive extract: Coming to the Tour de France?

Lance Armstrong take note: A new study indicates an extract of propolis, a honeybee product, holds promise for helping endurance cyclists cope more effectively with the heat stress that develops during long-distance rides. That heat can diminish an athlete’s performance by fostering fatigue and dehydration.

Propolis is a resinous material that bees fashion from plant saps and the like. They use it to not only caulk small spaces in their hive but also to insulate and reinforce the hive’s support structures. But folk medicine has found plenty of uses, too, for propolis over the years — primarily in treating everything from burns and sore throats to impaired immunity. This gummy substance may even hold promise in fighting dental caries.

A key ingredient in propolis — caffeic acid phenethyl ester, or CAPE — exhibits strong antioxidant activity. So it can quench some of those tissue-damaging free radicals that the body produces during illness and stress.

A team of researchers headed by Yu-Jen Chen and Jasson Chiang of the Chinese Culture University’s Graduate Institute of Sport Coaching Science, in Taipei, is now probing CAPE’s potential to protect certain white blood cells. Known as mononuclear cells, these immune-system players tackle infection by inducing localized inflammation. They can also cause damage by triggering inappropriate or overzealous inflammation.

For their new study, the Taiwanese researchers recruited 16 men. Although all had been in training as endurance cyclists for at least two years, during the four months leading up to their blood tests none had been training intensively — you know, cycling more than 150 kilometers (93 miles) a week.

Mononuclear cells were extracted from each man’s blood and then gradually heated up from a healthy 37 °C (98.6 °F) to a blistering 43 °C (109.4 °F) — and then maintained at that elevated temperature for an hour. Some samples of the blood were heated as is; others were first incubated with various concentrations of CAPE. Although the blood got really hot, peak temperatures replicated what can develop in a cyclist’s body, the authors say — that is, muscle temps of up to 45 °C and core body temperatures that can climb to 44 °C.

Heating killed off about 25 percent of the untreated cells, while virtually all of those incubated with CAPE at 2 to 4 micrograms per milliliter survived the thermal assault, the authors report in the August Journal of Food Science. Pretreated cells also proved less likely to exhibit evidence of being in their death throes following the test.

And what about those damaging free radicals? CAPE offered substantial protection. Post-heating concentrations of superoxide, for instance, were only a quarter to half as high in pretreated cells as in CAPEfree ones.

This propolis extract’s prowess in shielding an important class of white blood cells from the circulatory equivalent of heat stroke “implies that CAPE might play a role in preventing immunosuppression during an acute endurance exercise such as a bicycling competition,” Chen and Chiang’s team concludes.

The body normally turns on the production of heat-shock proteins to help people cope when the internal mercury rises. And preliminary data, the Taipei group reports, indicate that CAPE’s effects “may be partly mediated by overexpression of heat-shock protein by mononuclear cells.”

Of course, tests on blood incubated with a propolis ingredient are a long way from demonstrating whether humans would benefit from pre-race supplements of CAPE. But we can bet the racing world will be following this research. As yesterday’s ruckus over the advantage offered by polyurethane body suits in swimming points out, competitive athletes will look for any and every advantage that will help them beat the clock.

Janet Raloff is the Editor, Digital of Science News Explores, a daily online magazine for middle school students. She started at Science News in 1977 as the environment and policy writer, specializing in toxicology. To her never-ending surprise, her daughter became a toxicologist.

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