In the center of the Venn diagram of "incredibly tasty foods" and "incredibly nutritious foods" sit a select few of nature's treats. Among them is the sweet potato—in part for its versatility and in part for its satisfying texture and taste. After all, what other veggie can you roast, mash, spiralize, slice and bake into fries, and transform into grain-free brownies? Seriously, take a minute to think about that.
Here, learn everything you'd ever want to know about sweet potatoes—including seven compelling health benefits—that will inspire you to eat this superfood daily.
A brief history of the sweet potato.
Sweet potatoes are starchy root vegetables1. Specifically, they're what's known as underground tubers, and they actually grow on the roots of a plant known as Ipomoea batatas. Today, sweet potatoes are grown worldwide, but where did they first appear, courtesy of Mother Nature?
For years, scientists have been debating this very question. Some argued that the Thanksgiving staple originated in North America, while others weren't so convinced. In 2018, research by a paleobotanist at Indiana University suggested that the sweet potato's actual continent of origin is Asia—and that this root veggie has been growing for way longer than we thought.
David Dilcher, a professor at IU-Bloomington, along with colleagues in India, recently identified 57-million-year-old leaf fossils from eastern India, suggesting that sweet potatoes trace their roots to this country. Specifically, the fossils were identified as members of the morning glory family—which includes sweet potatoes, among other plants. This was a game-changer, since previous fossil evidence led scientists to believe that the sweet potato's plant family originated in North America 35 million years ago.
Different types of sweet potatoes.
When you think of sweet potatoes, you probably think exclusively of bright-orange spuds, but there are actually several varieties of sweet potatoes. First, sweet potatoes are divided into two main categories: dry-fleshed and moist-fleshed.
Dry-fleshed sweet potatoes are starchier and have tan skin and light-colored flesh that can range from white to light yellow in color. These dry-fleshed sweet potatoes are more similar to "regular" potatoes than their moist-fleshed cousins.
Moist-fleshed sweet potatoes, on the other hand, are probably what you picture when you think of "sweet potatoes"—they have darker, reddish-brown peels and brilliant orange flesh. They're also sweeter than dry-fleshed sweet potatoes, which might help explain why they've become a favorite. There are approximately 6,500 varieties of sweet potato worldwide. While each of these varieties is unique in its own way, you'll typically hear people classify them more broadly by their color, particularly orange, white, and purple sweet potatoes.
Sweet potatoes vs. yams: What's the difference?
In some parts of the United States (and in Canada), sweet potatoes are often called and even labeled as yams. This is very misleading, however, since sweet potatoes and yams are two totally different things. For starters, yams can get much, much bigger than sweet potatoes. While some yams are potato-size, they can also grow up to 5 feet long and 132 pounds2.
Even though yams and sweet potatoes are both starchy tubers, they're only distantly related. In fact, they don't even look that much alike. While sweet potatoes are, you know, potato-shaped and come in, primarily, white, orange, and purple varieties, yams are longer and more cylindrical in shape with brown, bark-like skin and flesh that can be white, yellow, pink, or purple. You'll also notice a clear difference if you ever try to prepare both sweet potatoes and yams—yams are much harder to peel than potatoes. The difference is also clear in a taste test, with yams being less sweet, drier, and more starchy than sweet potatoes.
If you haven't noticed these differences, it might be because the "yams" you're eating are actually mislabeled sweet potatoes (true yams are typically only found in specialty grocery stores or international markets). The USDA actually requires that sweet potatoes labeled as "yams" also include the term "sweet potato" on their label, but this rule is frequently broken.
The health benefits of sweet potatoes.
Here are some of the biggest science-backed benefits associated with incorporating more sweet potatoes into your diet:
Sweet potatoes are insanely nutritious.
It's best to start with the basics, and the most basic fact about sweet potatoes is that they are thoroughly packed with nutrients. When it comes to their basic makeup, sweet potatoes3 are about 77 percent water, 20 percent carbohydrates, 1.6 percent protein, and 3 percent fiber. What's more, a medium sweet potato contains about 180 calories, while being a good source of a range of vitamins and minerals, including vitamin A, vitamin C, manganese, vitamin B6, magnesium, and potassium.
Their nutrient composition also makes them particularly great for sleep when consumed at dinner or as a late-night snack. "They are rich in potassium, which helps your muscles relax. They also have magnesium, which promotes GABA secretion in the brain—a relaxation-inducing neurotransmitter," says Vincent Pedre, M.D., gut health specialist and mbg Collective member. "And as a complex carb, they digest slowly, providing the steady energy your body needs to make it through the night in a fasting state."
Sweet potatoes may improve your memory.
Purple sweet potatoes, in particular, have been linked to better brain function. In animal studies4, purple sweet potatoes have been shown to protect the brain5 and improve learning6 and memory7. We can thank purple sweet potatoes' high levels of anthocyanins, antioxidants that help reduce inflammation8 and protect neurons against free radical damage, for this brain-boosting magic.
While no similar studies have been conducted to verify these results in humans, research has shown that people who eat a lot of antioxidant-rich fruits and vegetables lower their risk of developing dementia9.
Sweet potatoes are great for digestion and gut health.
Because sweet potatoes are excellent sources of not one but two kinds of fiber10, they're amazing for your digestion. Sweet potatoes contain both soluble and insoluble fiber. The human body can't digest either type—so instead of breaking down as they pass through the digestive tract, these fibers travel along intact, doing great things for your gut in the process.
Both types of fiber play an important role in keeping bowel movements11 regular. Soluble fiber (also known as viscous fiber) absorbs water, which softens stool, while insoluble (aka non-viscous) fiber doesn't absorb water and therefore adds bulk that makes stool solid.
Not only is eating a fiber-rich diet good for alleviating constipation, diarrhea, and bloating, it's also great for your colon and overall gut health. Fiber feeds the good bacteria in your gut and has been shown to promote the health12 of the cells13 lining the digestive tract, potentially helping to prevent leaky gut. Eating a high-fiber diet14 has also been shown to lower the risk of colon cancer15.
The antioxidants in sweet potatoes may also promote gut health. In test-tube studies16, antioxidants in purple sweet potatoes17 were shown to aid in the growth of a specific type of gut bacteria18 that helps lower the risk of developing irritable bowel syndrome19 (IBS).
Sweet potatoes are full of age-defying antioxidants.
In addition to vitamins and minerals, sweet potatoes are also home to a wealth of antioxidants20. This is especially true of orange and purple sweet potatoes21. Antioxidants22 are important because they help protect your body from free radicals23—unstable molecules that damage DNA, cause inflammation, and have been linked to chronic and serious health conditions, like cancer and heart disease. In basic terms, free radicals accelerate the overall aging process. This means that just about any source of antioxidants24 is a good addition to your diet.
In addition to anthocyanins found in purple sweet potatoes, orange sweet potatoes are chock-full of an antioxidant called beta-carotene. This compound is what gives traditional sweet potatoes their signature orange hue. When your body processes beta-carotene, it turns it into vitamin A25, which is key to maintaining healthy eyes and vision26. Additionally, beta-carotene is fabulous for the skin. Not only do food sources of beta-carotene literally give your skin a natural glow, but research shows that they help protect skin27 from the sun's damaging UV rays.
Sweet potatoes may boost your immune system.
The next time you're looking to boost your immune system, don't simply reach for orange juice or vitamin C—add an orange sweet potato to the mix, too (they make a great addition to smoothies). As one of the best natural sources of beta-carotene, orange sweet potatoes28 are a great source of vitamin A (beta-carotene is converted to vitamin A in the body), which is vital to healthy immune system29 functioning.
Additionally, the fiber content of sweet potatoes can also boost immune health. Fiber is needed to feed beneficial gut bacteria so they can multiply and improve overall gut health. A healthy gut, in turn, is key to optimal immune system functioning, as about 80 percent of the immune system lies in the gut and is heavily influenced by what happens there.
Sweet potatoes may have anti-cancer properties.
If you're looking to adopt an anti-cancer diet, eating more purple sweet potatoes is a great idea. As mentioned above, they contain antioxidants called anthocyanins30, which have been shown to help slow the growth of cancer cells (including bladder cancer31, colon cancer, stomach cancer, and breast cancer cells) in test-tube studies32. Similar studies33 on mice have shown that eating purple sweet potatoes may lower the risk of colon cancer. These results have yet to be replicated in humans, but they're still promising. Beta-carotene from orange sweet potatoes may also help reduce the risk of various cancers, including lung cancer34.
Sweet potatoes are a diabetes-friendly food.
Some evidence suggests that regularly eating sweet potatoes35 may help improve blood sugar regulation in people with type 2 diabetes. That said, people with diabetes should watch their serving size, since this root vegetable still has a medium to high glycemic index (which measures how fast a food causes blood sugar values to rise after a meal). If you struggle with diabetes and love sweet potatoes, keep in mind that boiled sweet potatoes seem to have a lower glycemic index36 value than fried, roasted, or baked sweet potatoes do. Pairing sweet potatoes with a good protein source and other fiber-rich foods also reduces their glycemic load.
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Kayleigh Roberts is a freelance writer and editor living in Los Angeles, California. She earned a B.S. from the Medill School of Journalism at Northwestern University. She covers culture, entertainment, and health and has written for several notable publications including Elle, Marie Claire, and The Atlantic.