OUR SUPER STAPLE
Prevent cancer
Control high blood pressure and diabetes
Early in the history of the New World, in the Andes Mountains of Peru and Bolivia, people had a thousand names for the potato. It was that important.
In the 4,000 or so years since, the starchy tuber’s reputation has peaked and dipped. The Spanish conquistadors thought the new root captivating enough to take back to the Old World. (Within a few years, potatoes became standard fare on Spanish ships because they prevented scurvy.) Once the potato arrived in Europe, though, its fortunes sagged, not because of any shortcomings of its own but because of its kinship with the deadly nightshade family, plants that had the reputation for being toxic. Potatoes were feared rather than appreciated.
Eventually, though, both botanists and diners alike learned the whole story. Potatoes aren’t remotely dangerous. Plus, they’re a super food staple, making them the world’s number one vegetable crop.
“The potato has a little bit of almost everything,” says Mark Kestin, PhD, professor of nutrition at Bastyr University and affiliate assistant professor of epidemiology at the University of Washington, both in Seattle. “You could get many of your nutritional needs met from potatoes, if you had to,” he adds. Indeed. One large baked potato with the skin provides 48 percent of the Daily Value (DV) for vitamin C, about 40 percent of the DV for vitamin B6, about 30 percent of the DV for copper, manganese, and potassium, as well as 7 grams of fiber.
A potato’s healing abilities start in the peel, which contains an anticarcinogenic compound called chlorogenic acid, says Mary Ellen Camire, PhD, professor in the department of food science and human nutrition at the University of Maine in Orono. In laboratory studies, this particular acid has been shown to help the fiber in potatoes absorb benzo(a)pyrene, a potential carcinogen found in smoked foods such as grilled hamburgers. “The acid in the food reacts with the carcinogen by basically binding it up and making too big a molecule for the body to absorb,” she explains. “In our study, it prevented the carcinogen from being absorbed almost completely.”
Potatoes aren’t all created equal. Some taste better baked, while others are good for soups or salads. A third type, the all-purpose potato, has been “designed” both for baking and steaming. Here’s what to look for when considering potatoes:
Waxy potatoes. Known as round whites or round reds, waxy potatoes are low in starch and have a high moisture content. These potatoes keep their shape well during cooking, making them a good choice for soups, stews, and salads.
Starchy potatoes. The russet potato is a common type of starchy spud. It has a mealy, floury interior, which works well for mashing or baking.
All-purpose potatoes. Spuds like long whites are great to keep on the shelf because they can be prepared any way—baked, boiled, or steamed.
We don’t normally think of potatoes as being high in potassium, but in fact, a baked 7-ounce spud contains more than twice the potassium of one medium-size banana. One baked potato with the skin will give you about 1,137 milligrams of potassium, almost a third of the DV for this mineral.
Potassium is important because it seems to calm the spiking effect that salt has on blood pressure. For some people, increasing potassium in their diets by eating potatoes could reduce the need for blood pressure medication, notes pharmacist Earl Mindell, R Ph, PhD, professor emeritus of nutrition at Pacific Western University in Los Angeles and author of Earl Mindell’s Food as Medicine. In one study of 54 people with high blood pressures, half added potassium-rich foods like potatoes to their diets, while the other half continued to eat their normal fare. By the end of the study, Dr. Mindell says, 81 percent of the potato eaters were able to control their blood pressures with less than half the medication they had used previously.
Recently, British scientists stumbled upon another compound inside potatoes that may help explain this veggie’s extraordinary ability to help you control your blood pressure. Called kukoamines, these compounds have previously only been documented in some Chinese herbal remedies, say scientists from England’s Institute of Food Research. “Potatoes have been cultivated for thousands of years, and we thought traditional crops were pretty well understood,” says food scientist Fred Mellon, PhD, from the Norwich-based institute. “But this surprise finding shows that even the most familiar of foods might conceal a hoard of health-promoting chemicals.”
White potatoes have gotten a lot of bad press in the past few years. This veggie has been vilified by nutrition researchers who say it can send blood sugar soaring, and by nutritionists who warn that, too often, potatoes are just a vehicle for oil, butter, sour cream, and/or salt (think french fries, scalloped potatoes, and baked potatoes with the works). Women who splurged on french fries just once a week were 21 percent more likely to get diabetes than those who ate none, found a recent 20-year Harvard School of Public Health study of 84,500 women. Eating five servings per week of any white potatoes—including mashed and baked—raised the risk by 14 percent over those who ate less than half a serving per week.
But you don’t have to give up spuds. Truth is, eaten in moderate quantities, with the peel on, potatoes remain a satisfying, nutritionally valuable food. In fact, the glycemic load (a measure of how much a regular serving of a food really raises your blood sugar) of a baked potato is on par with that of healthy grain foods such as barley and whole-wheat spaghetti, say blood sugar researchers from the University of Sydney, Australia. The danger? Eating potatoes every night (fried … or with butter) instead of choosing a variety of different veggies. (Plenty of us do just that. Potato consumption has doubled in the United States since 1970, and Americans eat more spuds than any other veggie.)
The humble spud also packs a surprising nutritional bonus—a healthy dose of vitamin C. We don’t think of vitamin C as affecting our blood sugar, but there’s emerging evidence that this powerful antioxidant vitamin, well-known for helping prevent heart disease, may be of help to people with diabetes. On top of this, vitamin C may also be effective in diminishing the damage to proteins caused by free radicals, dangerous oxygen molecules that damage tissues in the body.
In one study, researchers in the Netherlands found that men eating healthy diets, which were high not only in potatoes but also in fish, vegetables, and legumes, appeared to have a lower risk for diabetes. It’s not yet clear what the protective mechanism is, but researchers speculate that antioxidants, including vitamin C, may play a role in keeping excess sugar out of the bloodstream.
Because potatoes are high in complex carbohydrates, they’re also good for people who already have diabetes. Complex carbohydrates must be broken down into simple sugars before they’re absorbed into the bloodstream. This means that the sugars enter the bloodstream in a leisurely fashion rather than pouring in all at once. This, in turn, helps keep blood sugar levels stable, which is a critical part of controlling the disease.
Further, potatoes can be key players in helping people with diabetes keep their weight down, an important benefit because being overweight makes it more difficult for the body to produce enough insulin, the hormone that helps transport sugars out of the bloodstream and into individual cells. At the same time, being overweight makes the insulin that the body does produce work less efficiently. What potatoes do is keep you full so that you’re less likely to be hungry later on.
In a study of 41 hungry students at the University of Sydney in Australia, researchers found that spuds filled them up more than other foods, while at the same time delivering fewer calories. On a satiety scale that measured white bread at 100, oatmeal at 209, and fish at 225, potatoes were way ahead at 323.
Get a nutritional boost with Technicolor taters. Potatoes with gold, red, purple, and blue skin—and even some with gold, red, blue, orange, and purple flesh—are turning up at farmers’ markets and in the produce section of supermarkets, too. They look pretty on your plate—and offer an extra dose of disease-fighting phytochemicals such as beta-carotene, lutein, and zeaxanthin, say nutrition experts from the University of California, Berkeley.
Keep the peel. To take advantage of potatoes’ cancer-fighting abilities, you really have to eat the peel, says Dr. Camire. This can be particularly important when eating grilled foods, which leave small amounts of cancer-causing substances on the food. It would be nice if you could get a fast-food burger on a potato-peel bun, says Dr. Camire. “That would help absorb the carcinogens from the grilling,” she says.
A more practical solution is simply to add a baked potato or potato salad (with the peel) to your plate whenever you eat a grilled hamburger, a hot dog, or other smoky foods.
Cook them carefully. Although boiling is one of the most popular cooking methods for potatoes, it’s perhaps the worst choice for preserving nutrients, since vitamin C and some B vitamins are pulled out of the potatoes and into the cooking water. In fact, boiling potatoes can result in losing about half the vitamin C, a quarter of the folate (a B vitamin), and 40 percent of the potassium, says Marilyn A. Swanson, PhD, RD, adjunct associate professor of pediatrics at Baylor College of Medicine in Houston, Texas.
If you do boil potatoes, you can recapture some of the nutrients by saving the cooking water and adding it to other foods such as soups and stews.
Baking and steaming do a good job of tenderizing potatoes, while at the same time preserving more of their nutrients. “Microwaving is your first choice,” says Susan Thom, RD, a nutrition consultant in Brecksville, Ohio.
Prepare them late. Busy cooks have traditionally peeled and sliced potatoes ahead of time, then submerged them in water to keep them from darkening. This may keep potatoes looking fresh, but it also strips valuable nutrients. “You lose some of the soluble vitamins in the water,” says dietitian Mona Sutnick, RD, a nutrition consultant in Philadelphia.
Preheat the oven to 425°F. Coat a baking sheet with cooking spray.
Scrub the potatoes and pat dry with paper towels. Cut each potato lengthwise into 5 or 6 slices, then stack the slices and cut at ¼-inch intervals to make french fries.
In a large bowl, combine the ketchup, oil, vinegar, Worcestershire sauce, and salt. Add the potatoes and toss to coat.
Spread the potatoes evenly on the baking sheet. Bake for 20 minutes, then turn and bake for 10 to 15 minutes longer, or until tender and golden. Test for doneness by inserting the tip of a sharp knife into a fry.
Makes 4 servings
Calories: 185
Total fat: 4.7 g
Saturated fat: 0.3 g
Cholesterol: 0 mg
Sodium: 218 mg
Dietary fiber: 3 g