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MEDICINE | IN THE LAB

From lowly potato to super spud

A lower glycemic index? More disease-fighting nutrients? Anything's possible.

January 15, 2007|Karen Ravn | Special to The Times

YOU know the drill. Popular public figure falls from grace, loses wholesome image, seeks redemption through rehab. So who is it this time? The potato.

Back in the day, potatoes were considered perfectly respectable. Then came low-carbohydrate fad diets and word of perilous, potato-provoked spikes in blood sugars. And that was before news broke in 2002 about a possibly unhealthy relationship with the toxic chemical acrylamide.

Potatoes have had some very bad press of late, but now, in labs across the country, those spunky spuds may be staging a comeback.

A low-carb breed is already on the market; researchers have produced a low-acrylamide variety; and work is underway to try to solve the blood sugar problem too. But scientists aren't just patching up holes in the potato's resume. They're also working to give it some new assets.

The potatoes most of us eat are naturally high in vitamin C and potassium, but researchers hope to add other vitamins and minerals to the mix by taking advantage of the potato's huge gene pool.

"Modern domesticated potatoes use less than 1% of the diversity in the wild," says Roy Navarre, a research geneticist for the U.S. Department of Agriculture's Agricultural Research Service in Washington.

"Lots of traits in potatoes aren't developed," adds Caius Rommens, director of plant sciences at J.R. Simplot, an agribusiness company based in Idaho. "We want to try to unleash their potential."

That potential may include warding off cancer and heart disease, among other threats to our well-being. Down the road, shoppers may even find specialty potatoes in their grocery bins -- for pregnant women, men with prostate cancer or anybody worried about their vision. In fact, many believe that healthified potatoes could play a significant role in curing some of the world's ills -- in large part because they're so popular.

Per capita, Americans eat about 135 pounds of potatoes a year, according to the National Potato Council, far more than any other vegetable. "People eat so many, you can get a disproportionate effect by improving the nutrient value," says Walter De Jong, an assistant professor of plant breeding and genetics at Cornell University.

Less carbs, less toxic?

The first in the new wave of potatoes -- the low-carb SunLite -- made a big splash when it went on the market in 2005. It's sold as an all-purpose potato -- "You can bake it, boil it, slice it, dice it," says Tom Campbell, owner of the distributor, Tri-Campbell Enterprises in North Dakota -- but fries-wise, it leaves much to be desired.

The more carbs, the crispier and more golden the fries, Rommens says. And he should know: He spends his days at Simplot pursuing fry perfection.

In a paper published this month in the Journal of Agricultural and Food Chemistry, he and his colleagues report significant progress on that front -- a fry that's prettier, smells better and is significantly lower in acrylamide.

Acrylamide results from a chemical reaction -- between sugars and the amino acid asparagine -- that occurs when starchy foods are heated to such high temperatures that they turn brown (e.g., when bread and cookies are baked, cereals are processed, potatoes are baked or fried).

Although acrylamide has been shown to cause cancer in rats and mice, its risk to people -- if any -- is a matter of considerable debate and lacks definitive evidence. California wants to force food manufacturers to post warnings about acrylamide dangers in French fries and potato chips, but the Food and Drug Administration opposes such a step.

To create a potato that makes less acrylamide when heated, Rommens and his colleagues inserted pieces of DNA into the potatoes to "silence" two genes responsible for turning starch into sugars when raw potatoes get cold (for example, in storage) or stressed (for example, cut off the vine). This produced potatoes with less sugar and, consequently, fries with less acrylamide.

Simplot plans to further improve the potatoes before marketing them, and Rommens says he's already working to lower their glycemic index, a scale measuring how fast carb-containing foods raise blood-sugar levels.

"The glycemic index for potato is quite high, about 85," Rommens says. "We hope to get it down to 40 or 50." The glycemic index ranges from 1 to 100. A value of 54 or less is low. A value of 70 or more is high. Pure sugar is 100.

Chock-full of antioxidants

Researchers are also working to increase antioxidant levels in potatoes. The potatoes most of us eat are already a super source of one powerful antioxidant -- vitamin C -- with a medium-to-large potato providing, on average, about 45% of the recommended daily allowance. That's about as much as a serving of spinach, though considerably less than a cup of orange juice.

Flesh-colored potatoes already on the market are rich in one type of antioxidants, carotenoids, which give the spuds their pigment as well as various health advantages.

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