Focus on the Flu : Treating, Foods and the Flu

by National Institute of Health

(Page 7 of 15)

Foods and the Flu: Another Good Reason to Eat Your Whole Grains

Can what you eat affect a flu virus?

"You bet it can," says Melinda Beck, Ph.D., professor of pediatrics and nutrition at the University of North Carolina at Chapel Hill. In fact, according to Dr. Beck, it's more what you don't eat that counts.

Dr. Beck and her multidisciplinary team of colleagues are currently building upon an earlier discovery that in mice, a diet poor in the nutrient selenium causes mutations to occur in the influenza virus, making it more dangerous. Once the virus has changed, even mice whose diets are selenium-adequate are vulnerable to the more dangerous strain.

"These observations suggest a new area for flu researchers, namely the interaction between host nutrition and viral genetics," says Dr. Beck.

Selenium is found in plant foods, such as Brazil nuts and whole grain cereals, as well as in some meats and seafood. Its content in foods depends on the amount of selenium in the soil where the plants grow or animals graze. Selenium is incorporated into enzymes that have antioxidant properties. These enzymes are important in protecting cells from damage by free radicals that are produced during infection.

Selenium also has toxic properties if consumed in excess, so the Institute of Medicine has established a Tolerable Upper Limit for adults of 400 micrograms per day.

In a new project funded by the NIAID, Dr. Beck is further investigating the relationship between selenium deficiency and mutation of the influenza virus. Working with a team of virologists, immunologists, cell biologists, biochemists, and nutrition experts, she is exploring what happens at the cellular and molecular level when selenium-deficient mice as well as human epithelial cells growing in the laboratory are infected with an influenza virus.

Among other things, the team hopes to learn how the flu virus evolves in a selenium-deficient host, how the host's cells and immune system respond to the mutated virus, the amount of selenium required to prevent mutations from occurring, and whether a diet poor in other antioxidant nutrients, such as vitamin C, could also lead to viral mutations.

In a study comparing the effect of a mutated flu virus in mice with or without adequate selenium in their diets, the researchers found that half of the selenium-deficient mice died of infection-often within a few days-while no mice with adequate selenium died. The selenium-deficient mice had large amounts inflammation-promoting chemicals in their lungs, which may account for the extensive lung damage in those animals, notes Dr. Beck. "This finding is particularly interesting," she adds, "because deaths in humans infected with avian flu may be due to the body's inability to control inflammation."

Treating the Flu

Powdered Antibodies Could Have Health
Officials Breathing Easier in a Pandemic

If a pandemic were to occur, not only would the world need a preventive vaccine, it would also need effective treatments. A quick jolt of antibodies able to ward off a deadly flu strain could help protect individuals already exposed or at risk of exposure.

NIAID-funded researchers Stephen Cape, Ph.D., and Robert Sievers, Ph.D., of Aktiv-Dry, a biotechnology firm in Boulder, CO, think they have the answer: flu-fighting IgG antibodies that are inhaled as a dry powder rather than injected.

"In earlier studies, IgG antibodies have proven effective in fighting influenza in mice when delivered into the nasal cavity or the lungs," says Dr. Cape. "In powder form, they have the potential to be very useful in a global pandemic."

According to the two researchers, one of the foremost benefits of powdered influenza antibodies is their stability at room temperature, allowing them to be stored for long periods of time in the field. "This would be particularly useful in developing countries, where refrigeration may not be available," adds Dr. Sievers. In addition, the size of the particles is extremely small. One puff could deliver a high concentration of antibodies to the lungs with fewer side effects than an injection into muscle.

The technology used to produce the powdered antibodies employs carbon dioxide, which turns the antibodies, mixed in solution, into a fine mist. The mist is later dried in the presence of warm nitrogen to yield a powder.

At several scientific meetings in 2005, Dr. Cape and his colleagues presented data showing success in generating IgG particles of the right size to be readily inhaled using the Aktiv-Dry technique. Moreover, the particles were stable at room temperature and retained activity against influenza A.

Next, the team will test the powders in mice to see if the product works in living animals. The investigators will also continue work on making powdered forms of antiviral drugs.

About the Author

NIH is the nation's medical research agency - making important medical discoveries that improve health and save lives. The National Institutes of Health (NIH), a part of the U.S. Department of Health and Human Services, is the primary Federal agency for conducting and supporting medical research.