Sweet potatoes are nutritious root vegetables that are popular around the world. While the orange flesh of sweet potatoes contains plenty of vitamins and minerals, more and more evidence suggests that the skin may be the healthiest part.
Nutrient Density of Sweet Potato Skin
The skin of sweet potatoes is an extremely rich source of dietary fiber, minerals, and antioxidant plant compounds. Fiber is a type of carbohydrate that the body cannot digest. Eating enough fiber promotes regular bowel movements and gut health. The skin of a medium sweet potato contains around 4 grams of fiber, which is 14% of the daily recommended intake.
Sweet potato skin is particularly high in potassium, containing over 360 milligrams in the skin alone. That’s around 10% of the recommended daily amount. Potassium supports nerve signaling, muscle contractions, and maintaining normal blood pressure levels. The skin also provides some calcium, magnesium, and phosphorus.
Some of the most beneficial plant compounds in sweet potatoes are found within the skin. These include anthocyanins which give the purple-skinned varieties their unique color. Anthocyanins are powerful antioxidants that protect the body from free radical damage. The skin of orange sweet potatoes also contains carotenoid antioxidants like beta-carotene.
Vitamin Content in Sweet Potato Skin
Many important vitamins are found exclusively in the thin outermost layer of the sweet potato’s flesh, right below the skin. Leaving the skin on provides a significant amount of extra nutrition.
For example, over 90% of the vitamin A content of a sweet potato is stored in the skin and the region just below. Just half a medium sweet potato with the skin provides over 150% of the daily recommended intake of vitamin A. This essential vitamin supports immune function and plays a critical role in eye health.
The skin is also one of the most concentrated sources of vitamin C in the entire sweet potato. Vitamin C supports collagen production, iron absorption, and immune cell function. Other water-soluble vitamins like thiamin, riboflavin, niacin, and vitamin B6 are also retained when the skin is eaten.
Antimicrobial and Anti-Inflammatory Benefits
Interestingly, some research indicates components within sweet potato skins have natural antimicrobial and anti-inflammatory properties. When tested in a lab, extracts from the skin have been shown to inhibit the growth of certain strains of bacteria, yeasts, and molds.
More studies are needed, but scientists have observed that compounds in the skin called sporamins have an inhibitory effect on some inflammatory enzymes. Chronic inflammation is at the root of most diseases, so eating more sporamins could potentially help prevent inflammatory conditions.
Improved Fiber Intake
Given that the skin is incredibly high in fiber, leaving it on can drastically increase the fiber content of the sweet potato. Americans only get around half of the recommended daily fiber on average. Inadequate fiber intake is linked to constipation, weight gain, blood sugar spikes, and colon cancer risk.
Just one medium sweet potato without the skin has 3 grams of fiber. Add the skin, and the fiber count doubles or even triples. Eating the whole sweet potato can provide 10 or more grams of fiber, making it one of the best sources of fiber in the produce aisle.
Greater Nutrient Absorption
Some nutrients like beta-carotene are fat soluble rather than water soluble. This means they require fat to be present in order to be properly absorbed by the body. Leaving the sweet potato skin on provides a small amount of beneficial fats that can enhance the absorption of fat-soluble vitamins.
Vitamin A from plant sources is found in the form of beta-carotene. Studies show that beta-carotene is better absorbed when eaten with just a few grams of fat. The cell walls of the sweet potato skin contain small amounts of essential fatty acids that facilitate this absorption process.
Potential Downsides of Sweet Potato Skin
Eating sweet potato skin does come with a few potential downsides. First, there may be a slightly bitter flavor. Cooking the sweet potatoes well can help reduce any harshness. Second, the skin can get stuck in between teeth, so thorough brushing is a must. Finally, pesticide residue tends to accumulate on the outer surface of vegetables, so buying organic is ideal.
The skin contains much more insoluble fiber than soluble fiber. Insoluble fiber can’t be digested and adds bulk to stools. For some people with digestive conditions like IBS, insoluble fiber may exacerbate symptoms like constipation and bloating when consumed in excess. Removing the skin reduces insoluble fiber content for easier digestibility.
Ways to Include More Sweet Potato Skin
Here are some simple ways to get more nutrients from the sweet potato skin:
- Bake or roast: Cooking whole sweet potatoes intact allows the skin to soften and become edible.
- Steam: Place whole potatoes in a steaming basket. The skin easily separates after cooking.
- Microwave: Poke holes in whole sweet potatoes, then microwave until soft.
- Fry: Slice sweet potatoes into wedges with the skin on, then bake or fry.
- Mash: After cooking, scoop out all the flesh and mash it together with the skin.
- Soup: Add chopped sweet potato chunks with skin into soups and stews.
The skin can simply be eaten along with the flesh once cooked. Another easy method is blending the cooked flesh and skin together to make sweet potato puree. Sweet potato skin also adds fiber and texture when used in dips, baked goods, or other recipes.
Nutrition Facts of Sweet Potato Skin
Here’s how the nutrition facts of sweet potato skin compare to the flesh in a medium potato:
| Nutrient | Sweet Potato Flesh | Sweet Potato Skin |
|---|---|---|
| Calories | 112 | 44 |
| Carbs | 26 grams | 10 grams |
| Fiber | 3 grams | 4 grams |
| Vitamin A | 14,187 IU (283% DV) | 17,813 IU (356% DV) |
| Vitamin C | 19.6 mg (22% DV) | 33.0 mg (37% DV) |
| Potassium | 337 mg (7% DV) | 360 mg (8% DV) |
As shown, the skin provides more fiber, vitamin A, vitamin C, and potassium compared to the sweet potato flesh alone, despite being lower in calories and carbs. The skin concentrates certain nutrients more densely than the starchy interior.
Cooking Methods that Maintain Nutrition
To get the most nutrition from sweet potato skin, avoid overcooking them. High heat for too long can cause certain vitamins to break down. Here are some best practices for preparing sweet potatoes while preserving nutrients:
- Bake at 375°F – 400°F for 45 minutes max.
- Boil or steam for 15 minutes max.
- Microwave 6-8 minutes max.
- Roast at 400°F for 30 minutes.
- Saute over medium heat for 5-10 minutes.
Higher cooking temperatures and longer cooking times increase the loss of water-soluble vitamins. Overcooking can make the skin tough and leathery as well. For maximum nutrition, cook sweet potatoes until just fork tender.
Are Skin Carotenoids Healthier from Cooked or Raw?
Sweet potato skins contain beneficial carotenoids including beta-carotene, lutein, and zeaxanthin. Carotenoids are best absorbed when eaten cooked rather than raw. Heat helps break down the tough cell walls that encase these compounds.
One study found that cooking increased the bioavailability of beta-carotene in sweet potato flesh and skin by over 30 times compared to raw. Another study observed a 23-fold increase in the carotenoid content of steamed sweet potato skins versus raw.
While cooking does degrade some vitamins, it also boosts the availability of antioxidants like carotenoids. Light cooking methods until just tender provide the optimal balance.
Do Purple Sweet Potatoes Have More Antioxidants?
Colored varieties of sweet potato, like purple and red, are richer sources of antioxidant anthocyanins than traditional orange types. Much of these special antioxidants are found in the pigmented skin.
In multiple studies, extracts from purple sweet potato skin possessed the highest antioxidant activity and anthocyanin concentrations compared to all other parts. Leaving the nutritious purple skin intact boosts the overall health value.
However, orange sweet potatoes are still packed with beneficial carotenoids, vitamins, minerals, and fiber, especially within the skin. All colorful varieties of sweet potatoes have unique nutritional benefits when eaten whole.
Can Dogs Eat Sweet Potato Skin?
The skin of thoroughly cooked sweet potatoes is safe for dogs to eat. Many pet owners actually incorporate sweet potato skins into homemade dog food recipes.
Sweet potato skins contain lots of extra fiber to promote digestive regularity in dogs. The vitamin A also supports eye and skin health. As long as the skin is cooked first, it can be a nutritious supplement for dogs.
Conclusion
Sweet potato skins deserve more attention for their impressive nutrient quantities. The skin concentrates certain vitamins, minerals, fiber, and antioxidants even more than the flesh. Enjoying the whole vegetable with the skin provides a major nutrition boost.
The skin does contain more insoluble fiber that may irritate some digestive systems when eaten in excess. For most people though, consuming the skins is an effective strategy to increase fiber, potassium, vitamin A, vitamin C, and antioxidants.
Cooking techniques like baking, roasting, steaming, and microwaving allow the skin to become palatable and tender. Searing the skins also enhances the bioavailability of beneficial carotenoids. So don’t peel your sweet potatoes! The skin is brimming with extra nutrition to take advantage of.
