By Adam Marcus

MONDAY, April 17 (HealthSCOUT)-- A powerful antioxidant delivered as a lozenge or mist could be an effective shield against influenza, researchers report.

Glutathione, a molecule found in a wide range of foods, seems to keep flu at bay in mice exposed to the virus, new research shows.

The scientists caution that any commercial product made with glutathione would be no substitute for a yearly flu shot, which would offer much greater protection against infection. But, they say, the compound could offer supplemental protection against casual contact with the microbe -- say, for example, on an airplane or in a crowded subway car.

Many scientists and nutrition gurus have long advocated the antioxidant vitamin C as a way to ward off colds or shorten their bouts. Two-time Nobel Prize winner Linus Pauling became the biggest champion of the vitamin, even claiming that it could deflect cancer -- a claim that bruised his professional reputation.

But while evidence hasn't supported some of the more aggressive statements about antioxidants -- that they protect the heart, for example, or fight tumors -- the latest study does bolster the case that they are powerful immune-boosting agents.

When flu virus lands on cells in the oral and nasal cavities, it's not rampantly infectious. Only after immune system enzymes split specific viral proteins can the microbe co-opt host cells and convert them into factories for replicating its own genetic information.

These enzymes are called proteases, and blocking them is an effective strategy against infection. Indeed, cutting-edge AIDS treatment relies heavily on protease inhibitor drugs to suppress HIV, which causes the disease.

Perhaps to assist proteases, the presence of viruses leads to local bursts of oxidation of cells in mucous, damage which hampers the body's protease inhibitors. So Dean Jones, an Emory University biochemist, and his colleagues wondered if powerful antioxidants might foil infections by stopping the cascade triggered by oxidation.

Best protection at lower doses

In a series of tests, reported today at the Experimental Biology 2000 meeting in San Diego, Jones' group showed that modest doses of glutathione dramatically reduce virus production in infected cells in a lab dish. "We didn't prevent the first cells from being infected, but those cells did not produce nearly as much active virus particles" when they divided.

Jones' team then gave mice water laced with glutathione and exposed them to a strain of flu adapted to rodents. At high levels of virus, the antioxidant offered no protection. But at lower doses -- such as what a human might experience through casual contact with infected people -- animals that drank the doped liquid had markedly reduced virus production compared to their cage mates that didn't get treated.

Not only did the compound prevent serious flu in the animals that ate it, says Jones, but it did so even after initial infection with the virus -- suggesting that the effects of glutathione aren't particularly time-sensitive.

Jones' group also found that a double helping of antioxidants, the combination of glutathione and a form of vitamin C, was even more effective than glutathione alone.

The trick now, says Jones, is to determine the best way to administer glutathione. Packaging it in a lozenge or aerosol seems ideal, he says, because the molecule could get directly into the fluid that bathes the cells most vulnerable to flu virus.

Donald Reed, an antioxidant expert at Oregon State University in Corvallis, calls the latest work "an interesting lead" worth pursuing. But, he notes, since some cells don't process glutathione well -- first the cells must break it down into a component molecule, then remake it -- finding the right vehicle for humans will be critical if flu fighting is to take place.

(From HealthSCOUT)