When I was a kid growing up in British Columbia, my kale- and turnip-loving parents didn’t feed us processed sugar of any kind.
But once in a while, on a special occasion, we’d have sweet potatoes. When they were baking in the oven, our tiny cabin would fill with warmth (which was its own special treat, especially in the Canadian winter!) and the exquisite smell of sweet-potatoey goodness.
Clearly, I’m extremely fond of sweet potatoes. So when I decided to write an article about them, I had to check all my happy memories at the keyboard and look at the evidence.
Meet the Sweet Potato
Sweet potatoes (Ipomoea batatas) are large, starchy, sweet-tasting vegetables. They actually belong to the morning glory family.
Despite sharing a name, sweet potatoes are only distantly related to the potatoes we typically bake and turn into french fries and potato chips. Non-sweet potatoes (including red, white, russet, and Yukon gold varieties) are part of the edible nightshade family, whose members also include tomatoes, tomatillos, eggplants, peppers, pimentos, and goji berries.
Sweet potatoes are root tubers, meaning they store water and energy, including starch and other carbohydrates, underground. They draw upon these resources to feed the aboveground parts of the plant. Other root tubers include beets, carrots, parsnips, celeriac, and turnips.
The Origin of the Sweet Potato
Sweet potatoes are some of the oldest foods known to humanity.
They are native to Central and South America. We have fossil evidence that sweet potatoes were growing in the Americas 35 million years ago. But very recently, scientists discovered 57-million-year-old leaf fossils in India that appear to be ancient morning glory leaves. This could beat the American claim as the point of origin of the sweet potato family by about 22 million years (so not exactly a photo finish!).
Wherever and whenever they originated, and however they have traveled the globe, I’m incredibly thankful that most of us have sweet potatoes in our lives today.
I Yam What I Yam, But What’s a Yam?
Sweet potatoes are often called “yams,” but the resemblance is mostly skin-deep — and even that’s a stretch. Botanically, they aren’t even distant cousins.
True yams are related to grasses and lilies. Native to Africa and Asia, they typically have long, cylindrical shapes with thick, brown or black bark-like skin, and white, purple, or reddish flesh inside. Most yams are starchy, dry, and not sweet at all (despite the misleading name swap).
Sweet potatoes, on the other hand, are from the morning glory family. They usually have tapered ends, smoother skin, and — true to their name — a naturally sweet flavor.
Here’s where it gets confusing: In North America, many grocery stores label soft-fleshed sweet potatoes (like garnet or jewel varieties) as “yams.” Why? Because decades ago, when both firm and soft types of sweet potatoes started being sold, grocers needed a way to tell them apart. Since the soft ones looked more like yams, the name stuck — even though it’s botanically incorrect.
So, if you’re seeing “yams” at the supermarket, chances are good you’re looking at sweet potatoes in disguise. Real yams? You’ll likely need to visit an international or specialty market to find those.
How Many Sweet Potato Varieties Exist?
While most supermarkets carry one or two different types of sweet potatoes, more than 100 varieties are available in the United States. And I was amazed to discover that this represents only a tiny fraction of the total diversity of sweet potatoes.
The sweet potato geeks of the world may be fascinated to know that the International Potato Center in Peru maintains a gene bank consisting of over 6,500 varieties of sweet potato. I don’t know about you, but I wish I could try them all!
Sweet potato varieties range in color from dark red to brown to purple to orange-yellow to white, with different tastes, sizes, shapes, and textures.
Here are Just a Few of the Most Popular Types of Sweet Potatoes:
- Beauregard, garnet, and jewel sweet potatoes are known for their reddish-orange skin and deep orange flesh. These are often the ones masquerading as yams at mainstream grocery stores. Who knew sweet potatoes could be so sneaky?
- White sweet potatoes are crumbly, with white flesh and golden-brown skin. They don’t contain as many antioxidants as orange varieties.
- Japanese or Satsumaimo sweet potatoes are known for being sweeter than most other types. This is especially true when they start caramelizing in the oven.
- Okinawan sweet potatoes are also known as purple sweet potatoes because of their high anthocyanin content. Anthocyanins are the pigments that give red, blue, and violet plant foods their beautiful colors. Anthocyanins are also what give Okinawan potatoes 150% more antioxidant power than blueberries.
Despite their name, Okinawan potatoes are native to the Americas. They were brought over to Japan sometime in the 16th century, where they grew well and have become a staple in many Japanese dishes. In North America, true purple sweet potatoes are most likely to be found in an Asian supermarket.
Sweet potatoes are very hardy vegetables. They’re able to grow at many altitudes, in many climates, and under compromised soil conditions. Even if you don’t have the greenest of thumbs, sweet potatoes are pretty forgiving with just a little TLC (Tuber Loving Care).
What Makes a Sweet Potato Sweet?
Have you ever smelled sweet potatoes caramelizing in the oven, or used them to make a pie or a cake?
If so, you know that even though they aren’t closely related to potatoes, at least the “sweet” part of their name is entirely appropriate.
When sweet potatoes are heated, an enzyme starts breaking down their starch into a sugar called maltose. Maltose isn’t as sweet as table sugar. But it’s enough to satisfy a sweet tooth that hasn’t been entirely overwhelmed by M&M’s and HERSHEY’S KISSES.
You can control the sweetness of sweet potatoes somewhat by how you cook them. Cooking sweet potatoes quickly (for instance, by steaming them or cutting them into smaller pieces before roasting) can reduce their ultimate sweetness.
On the other hand, cooking sweet potatoes slowly on low heat allows the maltose-making enzyme more time to convert the starch into sugar, giving you sweeter sweet potatoes.
Looking for even more control over the sweetness? The sweet potato enzyme is activated once it reaches around 135 F and stops working at around 170 F. (That’s 57 to 77 C). So the more time they spend in that range, the sweeter they’ll be.
Are Sweet Potatoes Good for You?
The people of Okinawa, Japan, have traditionally enjoyed one of the highest life expectancies in the world, as I discovered when my dad was researching his book Healthy at 100: The Scientifically Proven Secrets of the World’s Healthiest and Longest-Lived Peoples.
One of those secrets, it turns out, is lots and lots of sweet potatoes. The traditional Okinawan diet consists of minimal meat, dairy, eggs, and processed foods. Instead, they eat mostly whole plant foods, and they get a remarkable 60% of their calories from sweet potatoes alone.
It’s partly because of this high-fiber and antioxidant-rich dietary pattern that Okinawans enjoy such a long lifespan. Living to be one hundred years or older is not uncommon in Okinawa. Okinawans also experience less chronic disease than Americans do, with significantly fewer deaths from heart disease and cancers of the colon, breast, and prostate.
Traditional Papua New Guinea Highlanders have also been known to eat a lot of sweet potatoes. Tubers like sweet potatoes (and yams) have traditionally provided 90% of their calories!
They don’t eat much, if any, meat either. How has a sweet potato-based diet affected their health?
A study published in the Journal of Internal Medicine in 1994 found that when these native groups still followed this traditional way of eating, they enjoyed lower blood pressure and weight than Westerners, and they almost never experienced heart disease, strokes, or other modern chronic diseases.
So, are sweet potatoes healthy? It sure seems like it!
What makes them so good for you?
Sweet Potato Nutrition
Sweet potatoes are high in fiber, vitamin C, potassium, pantothenic acid (vitamin B5), niacin (vitamin B3), vitamin B6, manganese, magnesium, and copper. They also contain a modest but helpful amount of protein, around 4 grams per cup when cooked.
When compared to true potatoes, sweet potatoes offer more vitamins and antioxidants. The orange ones get their color from beta-carotene, which is a pigment and antioxidant.
But the greatest sweet potato nutritional glory of all may be its rich supply of vitamin A.
Sweet Potatoes Are Remarkably High in Vitamin A
Vitamin A deficiency is the world’s foremost preventable cause of childhood blindness. Each year, it blinds an estimated 250,000–500,000 children, and half of them die within twelve months of losing their sight.
For more than two decades, governments, foundations, and biotechnology firms have poured hundreds of millions of dollars into “Golden Rice.” This is a form of rice that’s been genetically engineered to provide beta-carotene (a precursor to vitamin A). Despite decades of effort, the product has still not reached the market in most of the world. And now, in a striking twist, even the Philippines — the first country to approve Golden Rice for commercial planting — has revoked its permit, citing safety concerns and a lack of scientific consensus.
Meanwhile, an off-the-shelf alternative has been waiting in plain sight: the orange-fleshed sweet potato. These sweet potatoes pack far more beta-carotene than Golden Rice ever promised, thrive in many of the same climates, and can be replanted from cuttings without licensing fees. Directing even a fraction of the world’s bioengineering budget toward distributing sweet potato cuttings and training farmers could have improved children’s diets for decades.
The shortcomings of the biotech approach were underscored in 2018, when the U.S. Food and Drug Administration concluded its consultation process on Golden Rice, informing the current developers, the International Rice Research Institute (IRRI), that Golden Rice does not meet the nutritional requirements to make a health claim.
In effect, the FDA was saying that GMO Golden Rice offers no meaningful nutritional benefits.
Which again raises the question: How much better off would people be if the hundreds of millions of dollars spent on developing Golden Rice had instead been used to support the growth of sweet potatoes, carrots, and other vitamin A-rich vegetables in parts of the world where vitamin A deficiencies are a problem?
Of course, that wouldn’t have made biotech company Syngenta any money. But it would have helped a whole lot more people than Golden Rice ever has, and most likely, ever will.
10 Incredible Sweet Potato Benefits
The unique nutritional profile of sweet potatoes makes them powerful allies in preventing disease and supporting overall health.
Here are some benefits of adding sweet potatoes to your diet.
1. Sweet Potatoes Support Digestive Health
Sweet potatoes are an excellent source of fiber, especially their skin. Fiber is important for your digestive health, preventing constipation and more serious diseases like colon cancer.
One medium sweet potato has about four grams of dietary fiber. Sweet potatoes also contain resistant starch, a type of starch that plays a role in feeding your body’s “good” bacteria.
2. Sweet Potatoes Keep Your Heart Healthy
The high fiber content of sweet potatoes can lower LDL (bad) cholesterol levels, helping to prevent cardiovascular disease.
Sweet potatoes are also high in potassium, which works in balance with sodium in your body to maintain healthy blood pressure.
They’re also high in copper, an essential metal for making red blood cells and keeping your heart healthy. Low levels of copper have been linked to dangerously high homocysteine, blood pressure, and LDL cholesterol levels.
3. Sweet Potatoes Could Actually Help Stabilize Blood Sugar
Since sweet potatoes are so, well, sweet, will they spike your blood sugar? Surprisingly enough, their glycemic load is moderate. Thanks to their fiber and complex carbs, they tend to cause a slower, steadier rise in blood sugar than true (not sweet) potatoes. And how they’re cooked matters, too. Boiling brings down their glycemic load, while baking or roasting tends to raise it.
In addition to their fiber and complex carbohydrates, which stabilize blood sugar and help you feel full longer, sweet potatoes contain other substances that help stabilize blood sugar.
A 2004 study published in Diabetes Care successfully used Caiapo, an extract from white sweet potatoes, to naturally reduce and manage blood glucose levels in people with type 2 diabetes. Participants who consumed just 4 grams of Caiapo every day for 12 weeks saw significant reductions in their A1C and other blood sugar metrics compared to placebo.
4. Sweet Potatoes Can Boost Your Immunity
Sweet potatoes are rich in antioxidants that prevent free radical damage in your body.
One cup of baked sweet potato contains about half of your daily value for vitamin C, which is important for wound healing and tissue repair. That’s a rough average, since variations in how you prepare the sweet potatoes and which variety you’re preparing can raise or lower the amount.
What’s more, the vitamin A in sweet potatoes helps your body make immune cells that stave off infections and disease and have anti-tumor effects. Purple sweet potatoes contain especially potent antioxidants.
5. Sweet Potatoes Are Good for Your Eyes
Sweet potatoes contain several nutrients that have been linked to improved eye health and vision. Some of the most powerful are the carotenoids, including alpha-carotene, beta-carotene, lutein, and zeaxanthin.
Beta-carotene, when taken as a supplement in isolation from the other carotenoids, can cause imbalances. But when eaten in foods, where it is always accompanied by, and in balance with, an entire suite of carotenoids, it’s been shown to have powerful anti-cancer and vision-enhancing properties.
Orange sweet potatoes (as well as other orange plants, including carrots and orange bell peppers) have particularly high concentrations of carotenoids.
It’s not just the orange sweet potatoes that are good for your vision, though. A class of anthocyanins called PSPA, derived from purple sweet potato roots, might also benefit your eyes.
A study published in Food & Nutrition Research in 2015 looked at whether PSPA could influence the health and growth of human retinal pigment epithelial (RPE) cells. These cells are responsible for helping your eyes absorb light, as well as directing the immune response to a threat to eye health. The researchers found that PSPA promoted DNA synthesis and healthy RPE cell growth and survival. You don’t have to wait for a supplement company to produce a formulation of PSPA to protect your vision; you can eat some purple sweet potatoes today!
6. Sweet Potatoes Fuel Your Brain
Sweet potatoes also contain compounds that help your brain function at its best, including choline and manganese.
Choline is an essential nutrient for brain growth and development. It’s also required for the synthesis of the neurotransmitter acetylcholine that sends messages between cells.
Manganese is also important for brain health. It binds to neurotransmitters and helps move electrical impulses through your body faster. You can find 43% of your daily value of manganese in one cup of baked sweet potato (based on a 2,000-calorie diet).
The anthocyanins unique to purple sweet potatoes may also have memory-enhancing properties, but I forgot what these are. (Kidding! They were found to help alcohol-stressed mice remember a task far better than mice who weren’t fed these anthocyanins. BTW, our view on the use of animals in medical research is here.)
7. They Can Help Ease Stress and Anxiety
Sweet potatoes may help you relax. They’re high in magnesium, which has been shown to play a role in calming the brain. Magnesium deficiency has been linked to depression, mood disturbances, and headaches.
For a comprehensive look at magnesium, including health benefits and where you can find it, check out this article, where you’ll learn that other good sources of magnesium include avocados, legumes, tofu, nuts, seeds, and leafy greens. (And clicking any of those links will send you to an article dedicated to that food.)
Or I can just cut to the chase and share a delicious, magnesium-rich meal that I’m dreaming about right now: a loaded baked sweet potato piled high with a soft nut cheeze, avocado, a drizzle of flax oil, and a sprinkle of seasoning, accompanied by some freshly steamed and piping hot leafy greens.
8. Sweet Potatoes Can Help Boost Fertility
Vitamin A is an essential nutrient for healthy reproduction, and as we know, sweet potatoes are a fantastic source.
Sweet potatoes also offer a moderate supply of iron. Evidence from the Nurses’ Health Study showed that women who consumed more non-heme iron (from plant sources like sweet potatoes) had a significantly lower risk of ovulatory infertility.
9. Sweet Potatoes Can Help Fight Cancer
Sweet potatoes are a rich source of cancer-fighting antioxidants, especially in their skin. They have other anti-cancer properties, too.
Up to 80% of the protein in sweet potatoes is a type of storage protein known as sporamin. This unique protein has been studied for its anti-cancer properties and has been found to inhibit tongue, gallbladder, and colorectal cancers. It has also been shown to be capable of slowing cancer cell growth and reducing cell migration and invasion in metastatic cancers.
Sweet potato peels, especially those of the purple varieties, may be especially powerful when it comes to cancer prevention.
A study published in Nutrition and Cancer in 2016 looked at the antioxidant and anti-cancer effects of an extract from sweet potato peels. They found promising anti-cancer activity for cancers of the breast, colon, ovary, lung, and head/neck.
10. Sweet Potatoes Have Anti-Inflammatory Effects
Eating sweet potatoes may also help reduce chronic inflammation, a condition that may be at the root of most, if not all, preventable diseases.
This is chiefly due to their high levels of beta-carotene, vitamin C, and magnesium. Their high levels of fiber and their abundance of antioxidants don’t hurt here, either.
One of the particular antioxidants that is found most abundantly in purple sweet potato flesh is cyanidin, which has been linked to reducing inflammation, especially in the digestive tract.
How to Choose and Store Sweet Potatoes
Next time you shop for sweet potatoes, here are a few things to keep in mind.
When you pick one up, take a close look at its skin (no, you don’t have to pack your magnifying glass). It should all be mostly the same color without visible signs of decay or cracking.
Give it a little squeeze. You don’t want your sweet potato to be squishy anywhere, as this could indicate rotting.
When you get your sweet potatoes home, find them a nice place to rest in a basket on your countertop or in your pantry. They should be kept dry and cool at room temperature, not refrigerated.
Typically, you should use sweet potatoes within a few weeks of purchase.
The Best Way to Prepare Sweet Potatoes
Maybe you eat sweet potatoes regularly. Or perhaps the only time they come to mind is when presented as a seasonal side dish.
Me? I’ve been known to enjoy a baked or steamed sweet potato for breakfast with a delicious organic tofu chive spread on it. Or for lunch with salad dressing or a peanut curry sauce. Or as a base for dinner, or even dessert.
About the only thing I haven’t tried is a steamed sweet potato smoothie (although, come to think of it, maybe I should!). Sweet potatoes are delicious, incredibly versatile, and can be eaten in more ways than you may think.
You can prepare them by boiling, steaming, baking, stir-frying, grilling, or cooking and mashing.
But the bottom line is: You just might want to cook sweet potatoes in whatever way makes you most likely to eat — and enjoy them.
The only way I’d recommend not preparing sweet potatoes is by deep-frying them. This isn’t the healthiest way to cook food anyway. But for sweet potatoes, it can actually lead to the creation of acrylamide, a potential carcinogen. That’s the same compound that forms in french fries — one more reason to skip the deep fryer and cook your tubers just about any other way.
If it works well with your recipe, try leaving the skin on for some potent fiber and nutrients. Sweet potato skin may have over 10 times the antioxidant power of the flesh inside.
Including a few grams of fat in your sweet potato recipes can significantly increase the amount of beta-carotene your body absorbs from the meal. Just use a small amount of nut butter, avocado, olive oil (if you use oil), or have a fat source in the same meal.
Can You Eat Sweet Potatoes Raw?
Regular raw potatoes, especially green ones, can contain the toxic enzyme solanine, so they shouldn’t be eaten raw. Sweet potatoes can be consumed without cooking; however, they might cause some digestive issues.
If you do decide to try them — maybe grated in a smoothie or salad — you may not want to eat too many raw sweet potatoes because they have an enzyme inhibitor that makes it harder for your body to digest protein and can make digestion difficult when consumed in large quantities. (Cooking destroys this protein inhibitor.)
Bloating, cramps, and gas may occur when eating raw sweet potatoes. They might also make you fart because they contain raffinose, one of the sugars responsible for flatulence. (Perhaps because I have twin sons, I somehow find it interesting that the word ends in “nose.”)5 Healthy Sweet Potato Recipes
My mouth is watering as I think about all the ways you can prepare sweet potatoes.
Check out some of these healthy recipes if you want some delicious ideas.
Think outside the box for breakfast with this delicious Avocado Sweet Potato Toast recipe. A thick slice of sweet potato makes an excellent (and creative) superfood swap on days when you are in the mood to mix things up. Piled high with avocado, radish, onion, arugula, broccoli sprouts, lemon, and oregano, this sweet and savory toast checks all the boxes for what a nourishing slice of toast should be! Tip: Make the sweet potatoes ahead of time so they can easily be warmed up and ready to eat all week long.
2. Sweet Potato Kale Bites
Sweet Potato Kale Bites are a fun and delicious bite-sized way to enjoy creamy sweet potatoes. These protein-packed, fiber-rich bites make a satisfying and sustainable snack for one, a crunchy, colorful appetizer for party guests, or a tasty, healthy treat for kids! Crispy on the outside and soft on the inside, this festive bite is sure to be a crowd favorite.
3. Buckwheat Sweet Potato Chili
Sweet potatoes are wonderfully versatile, with a delicate and sweet taste, they are an excellent addition to many savory (or sweet!) dishes, including our tasty Buckwheat Sweet Potato Chili! This chili is a comforting bowl of deliciousness that is packed with so much nutrition (and protein thanks to the buckwheat and black beans), and plenty of beta-carotene, B6, potassium, fiber, and vitamin C from the sweet potato. Together, buckwheat and sweet potato are a harmonious duo, so much so that you’ll be thinking up new ways to enjoy this delightful pairing again!
4. Southwest Stuffed Sweet Potatoes
Stuffed Sweet Potatoes reign supreme when it comes to a filling, delicious, and fun way to enjoy sweet potatoes! These naturally sweet orange vessels are power-packed with carotenes and fiber, plus space for a protein-packed and phytonutrient-rich black bean and sweet corn medley, delightfully creamy avocado, and flavorful herbs and spices. If you’re striving to center your nutrition around consuming nutrient-dense foods, this recipe certainly will help get you there!
5. Sweet Potato Pie Mousse
Unlock sweet potatoes’ naturally decadent side with this silky Sweet Potato Pie Mousse. Sweet potatoes, dates, and coconut milk come together to make a lightly sweet, whipped mousse with some autumn spice that will make you, your friends, and your family swoon. Double the recipe to make a scrumptious sweet potato pie filling!
Sweeten Your Health with Sweet Potatoes
Fiber, complex carbohydrates, vitamins, and minerals are essential for good health. And sweet potatoes are a fantastic way to add them to your diet.
Many of us have ancestors who reaped their benefits for a very long time, and there’s certainly no need to stop now. Luckily, sweet potatoes are affordable, easy to use and store, and available in many parts of the world all year long.
Sounds pretty sweet to me!
Tell us in the comments:
- Did anything in this article surprise you?
- Will you eat more sweet potatoes now?
- What’s your favorite way to enjoy sweet potatoes?
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Featured Image: iStock.com/Diane Labombarbe
