The beloved sweet potato may be sweet, but it's actually not a potato, nor is it a yam. The gorgeous orange root tuber hails from the morning glory family, while the white potato is from the nightshade family. But it’s what’s inside this vibrantly earthy vegetable that counts.

Root tubers like the sweet potato are known as perennating organs — thickened roots that serve as storage bins for a plant’s nutrients when above-ground conditions aren't good. They provide food for new shoots when the growing season returns. Root vegetables in general are the subterranean powerplants of the botanical world, and it often shows in their exuberant color and density of nutrients.

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Sweet potatoes in particular are wonderfully healthful. It’s been said that their easiness to grow and wealth of nutrients were an important factor in keeping Americans sustained through tough times, from colonial days through the Revolutionary War, Civil War and Great Depression. In times of prosperity, we may welcome them as vehicles for butter and goopy marshmallows, but sweet potatoes have so many other talents beyond supporting a holiday casserole. Consider the following:

1. They provide kind carbohydrates that don't induce a sugar crash

While white potatoes’ high glycemic index mean that their carbohydrates are quickly converted into sugar and a corresponding elevation in blood sugar levels, sweet potatoes are different. They fall much lower on the glycemic index which is better for avoiding sugar crashes and better for diabetes control, according to the American Journal of Clinical Nutrition. Sweet potatoes in moderate amounts can help maintain healthy blood sugar levels even for those with diabetes.

2. They keep your digestion running and help beat disease

One medium sweet potato with skin provides roughly between 4 to 6 grams of fiber, which doesn’t make them the highest fiber source from the plant world, but they pack a nice punch and are commonly included with foods recommended as good sources of the stuff. The National Institute of Medicine set the Dietary Reference Intake for fiber at 21 to 25 grams a day for women while men should get 30 to 38 grams per day. Most people don’t reach these levels. Fiber appears to reduce the risk of developing various conditions, including heart disease, diabetes, diverticular disease and constipation.

Baked sweet potato friesBaked sweet potato fries are relatively healthy and will make you happy. (Photo: Brent Hofacker/Shutterstock)
3. They may keep some cancers at bay

A study by the Harvard School of Public Health's Department of Nutrition found that for younger men, beta carotene — a fat-soluble plant pigment that can be converted into vitamin A — could provide protection against prostate cancer. Meanwhile, a Japanese study revealed that beta carotene may decrease the risk of colon cancer. Sweet potatoes have the highest amount of beta carotene of all fruits and vegetables.

4. They’re a prize for the eyes

All that beta carotene is great for the eyes as well. Ophthalmologist Jill Koury, M.D., says that vitamin A deficiency causes the outer segments of the eye's photoreceptors to deteriorate, damaging normal vision. Sweet potato’s high antioxidant levels from vitamins C and E are also very kind to the eyes and may prevent degenerative damage.

5. They could help conquer PMS blues

While huge amounts of manganese aren’t healthy, experts estimate that up to 37 percent of Americans don’t get the recommended dietary intake (RDI) of manganese in their diet. Along with promoting good bone health, one study found that boosting manganese intake from 1 mg to 5.6 mg of dietary manganese per day helped women with PMS to have fewer mood swings and cramps.

Sweet potato pieSneak extra nutrients in with sweet potato pie. (Photo: Lili Blankenhship/Shutterstock)

6. They are a boon for childbearing

Plant-based iron, like that found in sweet potatoes, can potentially promote fertility, according to the Harvard Medical School. The vitamin A from sweet potato’s beta carotene is also important for hormonal health during pregnancy and lactation.

7. They may tame inflammation

Sweet potatoes are a good source of choline, a micronutrient in the B-vitamin family. While choline is readily available in meat and eggs, good plant-based sources are harder to come by — but sweet potato can be counted as one of them. Choline helps with sleep, muscle movement, learning and memory, among other things, but it is also important in reducing chronic inflammation.

8. They help you not to die!

The National Health and Nutrition Examination Survey reveals that fewer than 2 percent of American adults get the 4,700 mg of daily recommended potassium — bad us! A medium sweet potato contains almost 500 mg, making it one of the higher potassium vegetables. Potassium helps the body work normally by helping nerves and muscles communicate and by transporting nutrients into cells and moving waste products out of them, among other tasks. A diet rich in potassium is important in offsetting sodium’s harm to blood pressure. Medical News Daily notes that a high potassium intake is associated with a 20 percent decreased risk of dying from all causes!

Bonus: Sweet potato vs. yam? In case you're wondering about the chronic confusion, we set the record straight: 18 commonly confused foods.