We love to mash, roast, bake, and fry sweet potatoes, but boiling is an often-overlooked way to cook them. Experts say boiling can actually make these sweet spuds even better for you. Here’s why.
All potatoes are starchy vegetables, but compared to white potatoes, sweet potatoes have a lower glycemic index (GI)—a scale from 0 to 100 that measures how quickly a food raises blood sugar.
Boiled sweet potatoes have an even lower GI than baked or roasted ones, Jennifer Scherer, MS, RDN, a registered dietitian nutritionist and owner of Fredericksburg Fitness Studio in Virginia, told Health. A boiled sweet potato has a GI of roughly 41 to 50, versus 79 to 94 for a roasted one.
That “can help prevent big spikes in blood sugar,” Scherer said.
Baking or roasting decreases the potato’s water content and concentrates its natural sugars. “It’s almost like comparing a grape to a raisin,” Ella Davar, RD, a registered dietitian in Miami Beach specializing in gut health and founder of the Gut-Brain Method, told Health. “A baked or roasted potato is like a raisin—there’s no water, so it’s more sugar with some fiber.”
Roasting a sweet potato removes some of its water content (which is why it shrinks in the oven). Boiling, however, allows the potatoes to absorb water and hold onto more moisture. Because boiled sweet potatoes start out more moist, you won’t need to add as much oil and butter, Davar said. That means less saturated fat, which can raise cholesterol and the risk of heart disease when consumed in excess.
Sweet potatoes are loaded with powerful antioxidants called anthocyanins, which help fight inflammation and oxidative stress. Anthocyanins may decrease the risk of diabetes by increasing insulin sensitivity, improving carbohydrate digestion, and supporting blood sugar regulation.
Sweet potatoes contain another group of antioxidants as well: carotenoids. The main one in sweet potatoes is beta-carotene, a precursor to vitamin A and the compound responsible for their orange color.
Boiling sweet potatoes—and steaming them—can help retain more of these antioxidants because these cooking methods break down the potatoes’ cell walls, making the compounds more accessible and easier for the body to absorb.
Another benefit of boiled sweet potatoes? Easier digestion, Scherer said. “Boiled sweet potatoes are soft and gentle on the digestive system,” she explained.
That’s because boiling breaks down some of the starches in sweet potatoes, and also increases a sweet potato’s resistant starch content—a type of fiber that supports gut health.
The peel of a sweet potato is packed with nutrients, so leave it on if you can when you boil it. (You can easily remove it after cooking if needed.) Either way, be sure to scrub the potato thoroughly first.
The cooking time will depend on the size of the potato if you’re boiling it whole, or how small the pieces are cut if you break it up. One method is to slice the potatoes into 1-inch rounds, cook them in gently boiling water with the lid on for 20 minutes, and then take the lid off for the last 10 minutes.
Not sure what to do with your sweet potatoes after they’ve been boiled? Here are a few ways to enjoy them:
- Keep them cubed: Scherer likes a quick, simple prep of boiled cubes tossed with olive oil, garlic, and herbs.
- Mash them: Davar recommends mashing boiled sweet potatoes with turmeric, coconut milk, and ghee. “Add a crack of black pepper for increased absorption of turmeric’s active compounds,” she said. Scherer mashes them with a little cinnamon and a touch of maple syrup for the ultimate comfort side dish.
- Toss them into a salad: Davar makes a warm salad of sweet potato, lentils, and arugula topped with pomegranate or pumpkin seeds and dressed with a vinaigrette of apple cider vinegar, Dijon mustard, and extra-virgin olive oil.
