From lowly potato to super spud
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.
But there are lots more antioxidants where those come from, many researchers believe.
“A potato is like a chemical cabinet of antioxidants,” says Chuck Brown, a research geneticist for the USDA’s Agricultural Research Service. “It’s not just a bag of starch.”
Rommens sees a day when potatoes could have 50 times more antioxidants than are available in store-bought potatoes now.
Brown, for example, is breeding potatoes especially rich in the carotenoids lutein and zeaxanthin, which have been shown to protect against macular degeneration and cataracts. He expects these potatoes to be available to consumers within two years.
Navarre is working to ratchet up potato levels of folic acid (a vitamin vital for pregnant women to protect their babies from certain birth defects), as well as flavonoids and phenolics, substances thought to fight cancer and promote cardiovascular health. At Texas A&M; University, research scientist Lavanya Reddivari is studying certain phenolics and carotenoids found in potatoes, both wild and cultivated, in hopes that they will help in the fight against prostate cancer.
Potatoes are naturally low in vitamin E, but David Douches, a plant geneticist at Michigan State University, is trying to change that in his breeding program.
While these researchers are hoping to create potatoes that go where no potato has gone before, Richard Novy is trying to make them better at what they already do well.
A research geneticist for the USDA’s Agricultural Research Service, Novy is working to breed potatoes with extra-high vitamin C content..
They’ll still have to pass the taste test
Consumers will have the final say on the potato healthification project, of course. The only genetically modified potato ever introduced in the United States, Monsanto’s NewLeaf, flunked the market test. Introduced in 1995, it was pulled six years later. But many experts believe that new potatoes will meet with better results. Most current potato research uses conventional -- and uncontroversial -- cross-breeding methods. For example, two strains that both contain a good deal of lutein are crossed in hopes of creating a new strain with even more lutein.
Some research programs do use genetic engineering, but often they use what Rommens calls “consideration of consumer interests in their choice of genetic elements.”
NewLeaf potatoes contained an extra gene from a bacterium, but in his own work on low-acrylamide potatoes, Rommens didn’t add any genes, but rather turned some off. And in his work to lower the glycemic index and increase antioxidant content, he is again tinkering with the genes already contained in the potato.
In his work on vitamin E, Douches has taken the next step and created a so-called transgenic potato by introducing non-potato genes. But these genes came, not from a bacterium, but from Arabidopsis thaliana, a small plant related to cabbage and mustard that has become a bioengineering favorite.
Douches believes that, with time, people will grow more comfortable with the notion of genetically modified foods. After all, he notes, some such foods have been on the market for 10 years.
More important, perhaps, he thinks people are likely to feel well disposed toward modification that is meant to give them “more nutritional bang for their vegetable.”
Historically, potato research focused mostly on increasing production, a matter of great importance to potato growers, but not to potato eaters. Monsanto’s NewLeaf, for example, was engineered to resist the Colorado potato beetle. It’s no wonder, really, that some people resisted it. What was in it for them? Nothing but a weird gene.
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Why mess with success?
Not everyone who keeps a close eye on potato research likes everything they see.
John Bamberg, project leader of the U.S. Potato Genebank, which collects, classifies, preserves, evaluates and distributes potato genes, hopes for more work on nutrients unique to potatoes or hard to get elsewhere. Tomatine and potato carboxypeptidase inhibitor, or PCI, for example, are considered powerful cancer fighters and could possibly be bred into potatoes in powerful amounts, Bamberg says.
Katherine Beals loves potatoes just the way they are, “nutrient-dense and so satiating.”
An associate professor in the division of nutrition at the University of Utah and a former consultant for the U.S. Potato Board, Beals stresses that acrylamide has never been shown to harm humans when consumed in normal amounts, and potatoes’ glycemic index varies depending on how they’re prepared and what they’re eaten with.
And Walter Willett thinks potatoes have been undeservedly popular for too long. The professor of epidemiology and nutrition at Harvard maintains that whole-grain alternatives -- such as brown rice, wheat berries, barley, quinoa -- are preferable.
All in all, he says, there’s really no good reason to try to make potatoes better. We should simply make them scarcer on our plates.