Sweet potatoes are sweet, starchy root vegetables packed with nutrients and grown worldwide. Coming in a variety of sizes and colors, including orange, white, and purple, they are rich in vitamins, minerals, antioxidants, and fiber. Sweet potatoes provide a number of health benefits and are easy to add to your diet. They can be eaten boiled, baked, steamed, or fried.
Nutritional Profile of Sweet Potatoes
Sweet potatoes are nutritious, packing a good amount of vitamin A, vitamin C, and manganese into each serving. The nutrition facts for 3.5 ounces (100 grams) of raw sweet potatoes are:
- Calories: 86
- Water: 77%
- Protein: 1.6 grams
- Carbs: 20.1 grams
- Sugar: 4.2 grams
- Fiber: 3 grams
- Fat: 0.1 grams
One cup, or 200 grams (g), of baked sweet potato with skin provides:
- Calories: 180
- Carbs: 41 g
- Protein: 4 g
- Fat: 0.3 g
- Fiber: 6.6 g
- Vitamin A: 213% of the Daily Value (DV)
- Vitamin C: 44% of the DV
- Manganese: 43% of the DV
- Copper: 36% of the DV
- Pantothenic acid: 35% of the DV
- Vitamin B6: 34% of the DV
- Potassium: 20% of the DV
- Niacin: 19% of the DV
In addition, sweet potatoes - especially the orange and purple varieties - are rich in antioxidants that protect your body from free radicals. Free radicals are unstable molecules that can damage DNA and trigger inflammation. Free radical damage has been linked to chronic illnesses like cancer, heart disease, and aging. Therefore, eating antioxidant-rich foods is good for your health.
Carbohydrate Content and Glycemic Index
A medium-sized sweet potato (boiled without the skin) contains 27 grams of carbs. The main components are starches, which make up 53% of the carb content. Simple sugars, such as glucose, fructose, sucrose, and maltose, comprise 32% of the carb content.
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Sweet potatoes have a medium to high glycemic index (GI), varying from 44-96. The GI is a measure of how fast your blood sugar levels rise after a meal. Given the relatively high GI of sweet potatoes, large amounts in a single meal may be unsuitable for people with type 2 diabetes. Notably, boiling seems to be associated with lower GI values than baking, frying, or roasting.
Starches are often split into three categories based on how well they’re digested. The starch proportions in sweet potatoes are as follows:
- Rapidly digested starch (80%). This starch is quickly broken down and absorbed, increasing the GI value.
- Slowly digested starch (9%). This type breaks down more slowly and causes a smaller rise in blood sugar levels.
- Resistant starch (11%). This one escapes digestion and acts like fiber, feeding your friendly gut bacteria. The amount of resistant starch may increase slightly by cooling the sweet potatoes after cooking.
Fiber Content and Gut Health Benefits
Cooked sweet potatoes are relatively high in fiber, with a medium-sized sweet potato containing 3.8 grams. The fibers are both soluble (15-23%) in the form of pectin, and insoluble (77-85%) in the form of cellulose, hemicellulose, and lignin. Soluble fibers, such as pectin, may increase fullness, decrease food intake, and reduce blood sugar spikes by slowing your digestion of sugars and starches. A high intake of insoluble fibers has been associated with health benefits, such as a reduced risk of diabetes and improved gut health.
The fiber and antioxidants in sweet potatoes can be beneficial for gut health. Sweet potatoes contain two types of fiber: soluble and insoluble. Your body cannot digest either type. Therefore, fiber stays within your digestive tract and provides a variety of gut-related health benefits. Certain types of soluble fiber - known as viscous fibers - absorb water and soften your stool. On the other hand, non-viscous, insoluble fibers don’t absorb water and add bulk.
Some soluble and insoluble fibers can also be fermented by the bacteria in your colon, creating compounds called short-chain fatty acids that fuel the cells of your intestinal lining and keep them healthy and strong. Fiber-rich diets containing 20-33 g of fiber per day have been linked to a lower risk of colon cancer and more regular bowel movements.
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The antioxidants in sweet potatoes may provide gut benefits as well. Test-tube studies have found that antioxidants in purple sweet potatoes promote the growth of healthy gut bacteria, including certain Bifidobacterium and Lactobacillus species. Greater amounts of these types of bacteria within the intestines are associated with better gut health and a lower risk of conditions like irritable bowel syndrome (IBS) and infectious diarrhea.
Protein Content and Sporamins
A medium-sized sweet potato holds 2 grams of protein, making it a poor protein source. Sweet potatoes contain sporamins, unique proteins that account for more than 80% of their total protein content. The sporamins are produced to facilitate healing whenever the plant is subjected to physical damage. Recent research suggests that they may have antioxidant properties. Despite being relatively low in protein, sweet potatoes are an important source of this macronutrient in many developing countries.
Vitamins and Minerals in Sweet Potatoes
Sweet potatoes are an excellent source of beta carotene, vitamin C, and potassium. The most abundant vitamins and minerals in this vegetable are:
- Pro-vitamin A: Sweet potatoes are rich in beta carotene, which your body can convert into vitamin A. Just 3.5 ounces (100 grams) of this vegetable provides the recommended daily amount of this vitamin.
- Vitamin C: This antioxidant may decrease the duration of the common cold and improve skin health.
- Potassium: Important for blood pressure control, this mineral may decrease your risk of heart disease.
- Manganese: This trace mineral is important for growth, development, and metabolism.
- Vitamin B6: This vitamin plays an important role in the conversion of food into energy.
- Vitamin B5: Also known as pantothenic acid, this vitamin is found to some extent in nearly all foods.
- Vitamin E: This powerful fat-soluble antioxidant may help protect your body against oxidative damage.
Plant Compounds and Antioxidants
Like other whole plant foods, sweet potatoes contain a number of plant compounds that may affect your health. These include:
- Beta carotene: An antioxidant carotenoid that your body converts into vitamin A. Adding fat to the meal can increase your absorption of this compound.
- Chlorogenic acid: This compound is the most abundant polyphenol antioxidant in sweet potatoes.
- Anthocyanins: Purple sweet potatoes are rich in anthocyanins, which possess strong antioxidant properties.
Notably, the antioxidant activity of sweet potatoes increases with the color intensity of their flesh. Deep-hued varieties, such as purple, deep orange, and red sweet potatoes, score the highest. The absorption of vitamin C and some antioxidants increases in sweet potatoes after cooking, while levels of other plant compounds may decrease slightly.
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Sweet potatoes offer various antioxidants, which may help protect against certain types of cancers. Anthocyanins - a group of antioxidants found in purple sweet potatoes - have been found to slow the growth of certain types of cancer cells in test-tube studies, including those of the bladder, colon, stomach, and breast. Similarly, mice fed diets rich in purple sweet potatoes showed lower rates of early-stage colon cancer - suggesting that the anthocyanins in the potatoes may have a protective effect. Extracts of sweet potato peels have also been found to have anti-cancer properties in test-tube and animal studies. However, studies have yet to test these effects in humans.
One animal study found that the anthocyanins in purple sweet potatoes could help protect the brain by reducing inflammation and preventing free radical damage. Another study found that supplementing with anthocyanin-rich sweet potato extract could reduce markers of inflammation and improve spatial working memory in mice, possibly due to its antioxidant properties. No studies have been done to test these effects in humans, but in general, diets rich in fruits, vegetables, and antioxidants are associated with a 13% lower risk of mental decline and dementia.
Sweet Potatoes vs. Regular Potatoes
Many people substitute regular potatoes for sweet potatoes, believing sweet potatoes to be the healthier choice. The two species contain similar amounts of water, carbs, fat, and protein. Notably, sweet potatoes sometimes have a lower GI and boast higher amounts of both sugar and fiber. Both are good sources of vitamin C and potassium, but sweet potatoes also provide excellent amounts of beta carotene, which your body can transform into vitamin A. Regular potatoes may be more filling but may also harbor glycoalkaloids, compounds that can be harmful in large amounts. Because of their fiber and vitamin contents, sweet potatoes are often considered the healthier choice between the two.
Health Benefits of Sweet Potatoes
Sweet potatoes have anticancer properties and may promote immune function and other health benefits.
Prevention of Vitamin A Deficiency
As vitamin A plays an important role in your body, deficiency in this essential nutrient is a major public health issue in many developing countries. Deficiency can cause both temporary and permanent damage to your eyes and even lead to blindness. It can also suppress immune function and increase mortality, especially among children and pregnant and lactating women.
Sweet potatoes are an excellent source of highly absorbable beta carotene, which your body can convert into vitamin A. The intensity of the yellow or orange color of the sweet potato is directly linked to its beta carotene content. Orange sweet potatoes have been shown to increase blood levels of vitamin A more than other beta carotene sources, as they contain a highly absorbable variety of this nutrient. This makes eating sweet potatoes an excellent strategy against vitamin A deficiency in developing countries.
Improved Blood Sugar Regulation
Imbalance in blood sugar levels and insulin secretion are the main characteristics of type 2 diabetes. Caiapo, a type of sweet potato with white skin and flesh, may improve symptoms in people with type 2 diabetes. This sweet potato may not only decrease fasting blood glucose and LDL (bad) cholesterol levels but also increase insulin sensitivity. However, the current data doesn’t justify the use of sweet potatoes in the treatment of type 2 diabetes. Further human research is needed.
Reduced Oxidative Damage and Cancer Risk
Oxidative damage to cells is often associated with increased risk of cancer, which occurs when cells divide uncontrollably. Diets rich in antioxidants, such as carotenoids, are associated with a lower risk of stomach, kidney, and breast cancers. Studies indicate that sweet potatoes’ potent antioxidants may reduce your risk of cancer. Purple potatoes have the highest antioxidant activity.
Eye Health
Sweet potatoes are incredibly rich in beta carotene, the antioxidant responsible for the vegetable’s bright orange color. In fact, one cup (200 g) of baked orange sweet potato with skin provides more than double the amount of beta carotene that the average adult needs per day. Beta carotene is converted to vitamin A in your body and used to form light-detecting receptors inside your eyes. Severe vitamin A deficiency is a concern in developing countries and can lead to a special type of blindness known as xerophthalmia. Eating foods rich in beta carotene, such as orange-fleshed sweet potatoes, may help prevent this condition.
Purple sweet potatoes also seem to have vision benefits. Older test-tube studies have found that the anthocyanins they provide can protect eye cells from damage, which may be significant to overall eye health.
Immune Function
Orange-fleshed sweet potatoes are one of the richest natural sources of beta carotene, a plant-based compound that is converted to vitamin A in your body. Vitamin A is critical to a healthy immune system, and low blood levels have been linked to reduced immunity. It’s also key for maintaining healthy mucous membranes, especially in the lining of your gut. The gut is where your body is exposed to many potential disease-causing pathogens. Sweet potatoes contain important vitamins like beta carotene, vitamin C, and potassium. They also contain fiber and can support a nutrient-rich diet.
Potential Downsides
Sweet potatoes are well tolerated in most people. However, they are considered fairly high in substances called oxalates, which may increase your risk of kidney stones. Individuals who are prone to getting kidney stones may want to limit their sweet potato intake.
How to Incorporate Sweet Potatoes into Your Diet
Sweet potatoes are available as fresh, frozen, or canned varieties. Store fresh sweet potatoes in a cool, dry place for up to one month.
Sweet potatoes are nutritious, high in fiber, very filling, and delicious. They can be eaten boiled, baked, steamed, or fried.
The Difference Depends on Color
Although most types of sweet potatoes have a similar vitamin and mineral content, an outstanding difference is their phytonutrient profile. All contain antioxidants, but the color of the flesh of a sweet potato determines the source and amount. Sweet potatoes with orange flesh are rich in carotenoids. In contrast, sweet potatoes with purple-colored flesh are rich in anthocyanins, the compound that gives them their rich, vibrant color. Carotenoids are yellow and orange pigments, synthesized by many plants, which function as a source of vitamin A (retinol) in your body. The most common carotenoids are beta carotenes, lutein, zeaxanthin and lycopene, according to the Harvard T.H. Chan School of Public Health. Carotenoids may be beneficial in enhancing your immune system and contribute to eye health. Anthocyanins are flavonoids naturally found in red, purple and blue fruits and berries.