So are potatoes good for you or not?
“Potatoes have gotten a bad rap because of the way they’ve been eaten and processed in the modern food system,” says Charles Mueller, Ph.D., a clinical associate professor in the Department of Nutrition and Food Studies at New York University.
Undoctored potatoes are healthy, says Mueller: They supply a good mix of nutrients. It’s when people deep-fry them in oil or smother them in butter, sour cream, or salt that spuds turn into nutritional duds.
A medium white baked potato (about 6 ounces) with skin has 159 calories, 36 grams of carbs, and nearly 4 grams of fiber. Potatoes also are packed with a healthy mixture of vitamins and minerals such as magnesium, potassium, and vitamins B6 and C. A medium potato, for example, supplies about 15 percent of your daily need for magnesium; and about 20 percent of your daily potassium need.
“Most people don’t get enough potassium their diet,” says Ellen Klosz, a Consumer Reports nutritionist. “It’s very important for helping to control blood pressure.”
And few Americans get the daily recommended amount of fiber, which has a slew of health benefits, from helping curb cholesterol, protect against diabetes, control weight, and even lower the risk of colorectal cancer. Dietary recommendations say most adults need around 25 to 30 grams of fiber per day. If you eat a medium potato with skin, you’ll get about 4 grams. If you eat one without it, you’ll only get about 3 grams. “It’s always good to eat potatoes with the skin,” says Mueller, “because you pick up some fiber.”
But Mueller says that you can greatly minimize the boost in blood sugar from potatoes if you eat them as part of a healthy meal that includes protein.
Another way to minimize the GI effect of potatoes is to cool them after cooking and either eat them cold (as in a potato salad) or reheat them. This alters the chemical structure of the potato’s carbohydrates, and forms resistant starch, a type of fermentable fiber that may lower blood sugar levels after a meal and have other health benefits.
Additionally, Klosz says, when you compare potatoes with other some other high GI staples, such as white rice, they’re actually much lower in calories and carbs, and supply more fiber.
For most people, having potatoes a couple of times a week can be part of a healthy diet, says Mueller. But only if you watch your serving size and what you put on them.
“Potatoes are among the most popular vegetables in the American diet,” Klosz says. “But most are consumed in their processed form, such as fries and chips. Only 26 percent of the potatoes we eat are fresh or unprocessed.” And even when eaten fresh, dousing them in butter or cream might negate their health benefits.
That might at least partially explain the findings of some observational studies, such as those from Harvard researchers, which found that eating potatoes frequently may increase the risk of high blood pressure, type 2 diabetes, and weight gain.
In one of the studies, people who ate potatoes two to four times per week had a modest increase in type 2 diabetes risk—7 percent—compared with those who ate them less than once a week. Those who had 7 servings a week, however, had a 33 percent increased risk. While all forms of potatoes—baked, boiled, fried, and mashed—were linked to the disease, French fries were most problematic.
That was also the case in the other Harvard studies. For instance, people who ate four or more servings of baked, boiled, or mashed potatoes had an 11 percent increased risk of high blood pressure compared to those who ate them less than once a month. For French fries, the risk was 17 percent higher.
People often make the mistake of counting potatoes as a vegetable in their meals. “While it is a tuber and it’s in the vegetable family,” says Mueller, “it is a starch, and should be considered equivalent to eating pasta, whole wheat pasta, whole wheat bread, or brown rice.” The Harvard studies suggest that if you replace potatoes with a nonstarchy vegetable or a whole grain in your meals, it helps protect against chronic health problems.
A Range of Colors
In addition to white potatoes, you can find yellow, purple, and red-fleshed varieties. The colors come from compounds in the plants called phytochemicals such as anthocyanins, carotenoids, and flavonoids, which have antioxidant properties and may protect against cardiovascular disease, cancer, and other chronic diseases. Red- and purple-fleshed potatoes have nearly twice the flavonoids as white ones.
What about sweet potatoes? Technically, they’re not really potatoes—they aren’t part of the same plant family—and they may be a little healthier. A medium sweet potato is just slightly lower in calories and carbs (147 calories; 35 grams of carbs) than a same-sized white version, but has about one more gram of fiber. And it provides enough carotenoids to supply more than five times your daily recommended dose of vitamin A. Purple sweet potatoes offer the highest levels of anthocyanins, a type of flavonoid linked to heart and liver benefits, compared with white, yellow, and orange-fleshed types.
How to Prepare Potatoes Healthfully
It’s pretty simple: Go easy on the potato toppings and add-ins. Just one pat of butter and two tablespoons of sour cream adds about 100 calories and 9 grams of fat. “When you add a lot of cream and butter and salt,” says Mueller, “you can increase the caloric value of them and you’re more likely to overeat.” Why? Because they taste good.
The same goes for sweet potatoes. Adding marshmallows, butter, and brown sugar ups the fat and sugar load significantly. There are 14 grams of sugars, and 9 grams of fat in a half-cup of sweet potato casserole vs. about 7 grams of sugars and no fat in a medium sweet potato. Avoid canned varieties packed in heavy syrup.
Fortunately, potatoes—whether sweet or regular—don’t need much to make them tasty. Cut them into cubes and roast with a little rosemary, olive oil, and salt and pepper; or boil or microwave them whole. When eating them baked or mashed, keep the condiments to a minimum.