The origin of the sweet potato is thought to be in either Central America or South America. In Central America, they were domesticated at least 5,000 years ago and in South America, remnants dated as far back as 8000 BC have been found.
Although the soft, orange sweet potato is often called a "yam" in parts of North America, the sweet potato is botanically very distinct from a genuine yam, which is native to Africa and Asia. Despite this confusion, the nutritional content is very similar.
As a root vegetable, it is a powerhouse of nutrients for the winter season, helping to build the immune system.
Top Nutrients in Sweet Potato
You'll get a respectable 4 grams of fibre and 3 grams of vegetable protein in one medium sweet potato. Flavorful and filling, a baked sweet potato is only 103 calories - and fat-free and low in sodium to boot!
The sweet potato really shines when comes to the B vitamin niacin, vitamin B-6 and vitamin A. For about 100 calories, you’ll get 69% of the RDA for niacin, 25% of the RDA for vitamin B-6 and 122% of the RDA for vitamin A in the form of beta-carotene.
Sweet potatoes also provide some calcium, iron, potassium and vitamin E. Here is the nutrition information for on medium baked sweet potato with the skin on:
Nutrient name & amount
Protein 2.29 g
Total Fat 0.17 g
Carbohydrate 23.61 g
Energy 103 kcal
Fibre, total dietary 3.8 g
Calcium 43 mg
Iron 0.79 mg
Potassium 542 mg
Sodium 41 mg
Beta carotene 13.12 mg
(Source: Canadian Nutrient File, 2007)
Top Phytochemicals in Sweet Potato
Sweet potatoes are an excellent source of beta-carotene, an antioxidant phytochemical that’s part of the carotenoid family. Beta-carotene, which our bodies convert to the active form of vitamin A, plays an important role in eye health as well as disease prevention and building our immune system. Although there is no official recommendation for beta-carotene, some health experts suggest daily consumption of 3 to 6 milligrams of this orange pigment to prevent chronic disease. Sweet potatoes out-rank other bright orange vegetables that contain beta-carotene:
Beta carotene (milligrams) - per 1/2 cup serving
Sweet potato 16.8
Carrot juice 11
Canned pumpkin 8.5
Cooked carrots 6.5
Raw carrots 4.6
Winter squash 2.9
(Source: Foods that Fight Disease, 2008)
Varieties of Sweet Potatoes
Not to be confused with yams which have off-white, yellow, purple or pink flesh that’s lower in vitamin C and A, sweet potatoes come in two main varieties - the moist (orange-fleshed) and dry (yellow-fleshed) sweet potato. The pale or dry sweet potato has a thin, light yellow skin and a pale yellow flesh. Its flavor is not sweet and after being cooked, it is dry and crumbly, similar to a white baking potato. The darker or moist variety has a thicker, dark orange skin and a bright orange flesh that is sweet and has a moist texture. The darker orange color also means that the moist sweet potato has more beta-carotene than the yellow dry sweet potato.
Tips on Buying and Enjoying the Sweet Potato
How to Choose Sweet Potato
Choose sweet potatoes that are small to medium-sized with smooth skins. The potatoes should be heavy for their size. You may find canned and frozen sweet potatoes in ethnic food markets. These may be labeled yams, although incorrectly. The canned ones are usually packed in heavy syrup or "candied" although some processors do pack them in water. To get maximum nutrition buying fresh sweet potatoes is recommended. Canned or processed sweet potatoes (including sweet potato fries) are lower in beta-carotene, vitamin C and B vitamins.
How to Wash Sweet Potato
Eating the sweet potato with the skin on imparts the maximum nutrition. Use a vegetable scrubbing brush to remove any traces of dirt while running cool water over your sweet potatoes. Ideally, sweet potatoes should be washed immediately before eating – instead of before storage – to minimize the risk of mold growth during storage.
How to Store Sweet Potato
Sweet potatoes should be stored in a cool, dry place – but not the refrigerator. Doing so will produce a hard core in the center and an "off" taste. If stored somewhere that is too cool, the natural sugars turn to starch which affects their flavor. Stored at lower than room temperature, sweet potatoes will keep for a month or longer. If kept at normal room temperature they should be used within a week of purchase. Cooked sweet potatoes freeze well. Wrap unpeeled cooked sweet potatoes individually in aluminum foil or freezer wrap. Place in plastic freezer bags, label, date and freeze.
How to Cook Sweet Potato
To get the most nutrition out of your sweet potatoes, cook and serve them with the skins on. Many of the nutrients - like fibre - are contained in the skin. Sweet potatoes have a very thin skin and should be handled carefully to prevent bruising. When cutting them always use a stainless steel knife or vegetable peeler. As with carrots (see above chart), exposure to heat during cooking heightens the bioavailability of beta carotene in sweet potatoes.
Baking: Pierce the potatoes with a fork or small knife before baking. This will let the steam escape. The potatoes tend to ooze sticky juices as they bake so you may want to put them on a foil-lined baking sheet. Cook for 30 to 60 minutes or until tender in a 400F oven. The bigger they are the longer they will take to fully cook.
Grilled: Wrap medium-size potatoes individually in heavy duty foil. Place on the grill about 5 inches from the coals. Cook for about 45 minutes or until tender. To speed up the process, boil 10 minutes before wrapping in foil.
Mashed: Place whole unpeeled potatoes in boiling water and cook 35-45 minutes, or until the potatoes give easily when pricked with a fork. If the potatoes have been cut into chunks, cooking time will be about 10 to 15 minutes. Drain immediately. You can leave the peel on for extra nutrients or remove them for a smoother mashed potato. Mash with a potato masher, fork or electric mixer.
Microwaving: For best results, choose uniformly sized potatoes. (e.g. do not vary much in width from center to ends) Pierce, place on paper towel and cook on high, turning each potato halfway through cooking time. Remove and wrap in aluminum foil and let stand for at least five minutes.
Microwave cooking times from the North Carolina Sweet Potato Commission:
· 1 medium: 3-4 minutes
· 2 medium: 5-6 minutes
· 3 medium: 7-8 minutes
· 4 medium: 8-9 minutes
Keep in mind that times may vary depending on microwave size and power.
Sautéed: In a large deep skillet, heat enough oil to cover the bottom of the pan. Add sweet potato strips to cover bottom of skillet. Sauté for five minutes or until brown and tender. Remove from hot oil and drain on paper towels.
How to Enjoy Sweet Potato
Sweet potatoes can be used in place of white potatoes or squash in most recipes. They are very versatile and can be added to soups, stews, curries, stir-fries and even baked goods. Before adding cooked sweet potato to a muffin, bread or pancake recipe, pureed the flesh in a food processor.
Looking for a new way to enjoy sweet potatoes? Instead of carrots, try grating raw sweet potato into your favorite coleslaw recipe for a boost of beta-carotene.
What’s a kid-friendly way to eat sweet potatoes? Make sweet potato chips by thinly slicing this nutritious tuber. Brush the slices with oil, season with salt, paprika and cumin for a savory snack or brown sugar and cinnamon for a sweet treat. Roast in a 400 F (200 C) oven until golden and crisp.
Main Health Benefits of Sweet Potatoes
Foods that are high in beta-carotene, like sweet potatoes, help prevent vitamin A deficiency which can cause dry eyes, dry skin, impaired bone growth and night blindness. In addition to maintain optimal health, the nutritious sweet potato may also play a role in preventing chronic diseases such as heart disease and lung cancer.
Studies have shown that high intake of carotenoids – like the beta-carotene in sweet potatoes – can reduce the risk of heart disease by preventing oxidation of “bad” LDL cholesterol in the bloodstream.
Research has also shown that lung cancer risk in smokers and non-smokers alike can be reduced by eating foods that are high in beta-carotene. However, high intake of this carotenoid by way of supplements can raise the risk of lung cancer in smokers.
Did you know that chopping, pureeing and cooking your sweet potatoes in a little bit of fat increases the absorption of beta-carotene? Drizzling just one teaspoon (5 ml) of extra virgin olive oil on your baked sweet potato boosts its benefits to your health.
Cheryl Wahl, RHN
Certified Professional Cancer Coach
 Am J Clin Nutr 2003, 77(6): 1390-99
 N J Engl Med 1994, 330(15): 1029-35
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