Sunday, March 28, 2010

Science Sunday: Amazing Antioxidants

You can't go into a supermarket these days without being bombarded with food labels touting products as being rich in antioxidants, wee molecules that naturally occur in certain foods and are added to many dietary supplements because of the belief that they help maintain good health and prevent diseases such as cancer and coronary heart disease.

I happen to maintain an antioxidant rich diet that includes lots of raw vegetables, grain cereals, legumes, nuts, eggs and berries -- oodles of berries, including wild blueberries -- and eat few processed foods. I do so because that's what I feel that is best for my bod, but these edibles also help me as a stroke victim who has rheumatoid arthritis.

As accidentally smart as my diet turns out to be, certain birds have we humans beat hands down: This is because bug-eating songbirds switch to berries rich in antioxidants before migrating south for the winter.

This abrupt dietary change has less to do with fattening up and more to do with stocking up on nutrients to help their bodies deal with the stress of migration, according to researchers.

"It has been known for some time, this phenomenon of birds switching to fruits in the fall," says bird researcher Scott McWilliams of the University of Rhode Island. It was assumed that the birds were packing in extra fats or carbs during cooler weeks when insects were on the wane. "But that didn't explain it enough."

So McWilliams teamed up with Navindra Seeram, the head of the university's Bioactive Botanical Research Laboratory, to see what was up with the fruits birds were choosing.

To collect the same berries as the birds were choosing, graduate student Jessica Bolser spent months in the field on Block Island, off the eastern tip of Rhode Island. Batches of 12 kinds of berries were brought back Seeram's lab where researcher Liya Li got to work on them.

"This study is one of the new generation of bird food studies that is . . . not just looking at energy and protein but looking at micronutrients," said ecologist Douglas Levey of the University of Florida in Gainesville.

"The whole twist of looking at the antioxidant qualities is novel," agreed migratory bird researcher David Bonter of the Cornell Lab of Ornithology, who noted that thrushes, sparrows, warblers and such evolved very specialized beaks for eating insects but suddenly switch to fruits.

"They look clumsy and ridiculous," Bonter said.

Indeed, but as so often happens in the animal world, the relationship between these bird and the berry bushes is mutually beneficial. The birds stock up on nutrients and the bushes get their seeds dispersed when the birds defecate.

The fruit-picking behavior itself remains something of a mystery, Bonter said, because its probably not something the birds learn since many are only eight to nine weeks old when they are readying to migrate.

Top photograph by Ryan Brady

1 comment:

John Freeland said...

Good article and photos. I love cedar waxwings.