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. 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. 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. 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. 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.” 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. 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). 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. 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.
