Sweet potato skin is not only safe to eat, it’s one of the most nutritious parts of the vegetable. The skin contains two to three times more antioxidants than the flesh, significantly more fiber, and has a dramatically lower glycemic index. If you’ve been peeling your sweet potatoes before cooking, you’re discarding a surprisingly valuable layer of nutrition.
Why the Skin Is More Nutritious Than the Flesh
USDA research on common sweet potato varieties found that the peel contains 145 to 182 mg of phenolic compounds per 100 grams of fresh weight, compared to roughly 20 to 60 mg in the flesh. That’s a two- to threefold difference in antioxidant concentration. The dominant compound is chlorogenic acid, which makes up 40% to 60% of the total phenolics in sweet potato roots and is linked to anti-inflammatory and blood-sugar-regulating effects. The skin simply packs these protective compounds more densely than the orange interior.
Beyond antioxidants, eating sweet potatoes with the skin on delivers four times the recommended daily amount of beta carotene compared to peeled sweet potatoes, according to the University of Arkansas Division of Agriculture. The skin also adds dietary fiber, which supports digestion and helps you feel full longer.
A Surprisingly Low Glycemic Index
One of the most compelling reasons to eat the skin is its effect on blood sugar. Research published in The Open Nutrition Journal measured the glycemic index of sweet potato skin versus flesh across different cooking methods, and the gap is striking.
- Steamed flesh: glycemic index of 63
- Steamed skin: glycemic index of 30
- Baked flesh: glycemic index of 64
- Baked skin: glycemic index of 34
- Raw skin: glycemic index of 19
The skin’s glycemic index was significantly lower than both the flesh and white potato in every comparison. This is likely due to the higher fiber and phenolic content in the skin, which slow the breakdown of starches into sugar. For anyone managing blood sugar or trying to keep meals lower on the glycemic scale, leaving the skin on is a simple, effective strategy.
Even more interesting: a commercial extract made from the outer layer of sweet potato (sold as Caiapo) was shown to lower the glycemic index of white potato when the two were consumed together. The bioactive compounds in sweet potato skin don’t just benefit sweet potato meals; they actively slow sugar absorption.
Best Cooking Methods for the Skin
How you cook sweet potatoes matters for both the skin’s texture and its nutritional value. Baking and steaming are your best options. Both methods soften the skin enough to eat comfortably while preserving most of the nutrients. Baked sweet potato skin develops a pleasant, slightly chewy texture that many people enjoy.
Boiling is fine too, but cook the sweet potatoes whole with the skin on. Cutting them before boiling allows some of the natural sugars and water-soluble nutrients, particularly vitamin C, to leach into the water. Keeping the skin intact acts as a barrier. If you do need to peel after boiling, the skin slides off easily and takes less of the flesh with it.
Vitamin C is sensitive to both heat and air exposure, so shorter cooking times and serving sweet potatoes hot helps preserve more of it. Microwaving works well for speed, though it raises the glycemic index of the flesh slightly more than steaming or baking (66 versus 63 to 64).
How to Clean Sweet Potato Skin
Sweet potatoes grow underground, so their skin tends to carry more dirt than most produce. A good scrub under running water is the most effective way to clean them. The National Pesticide Information Center recommends using a clean produce brush on firm vegetables like potatoes, which removes more residue than rinsing alone.
Skip the soap, detergent, or commercial produce washes. The FDA has found these are no more effective than plain water, and they can leave their own residues behind. Rubbing the skin under running water rather than soaking it in a bowl also does a better job of carrying away contaminants.
No washing method removes 100% of pesticide residues, but the combination of scrubbing and cooking reduces them substantially. If pesticide exposure is a concern, buying organic sweet potatoes is an option, though sweet potatoes generally rank lower in pesticide residues than many other produce items.
What About Taste and Texture?
Sweet potato skin has an earthier, slightly bitter flavor compared to the sweet flesh, which some people love and others tolerate for the nutritional benefits. Roasting at high heat (around 400°F) caramelizes the skin’s natural sugars, making it crispy and more palatable. Tossing cubed, skin-on sweet potatoes with olive oil and salt before roasting is one of the simplest ways to make the skin genuinely enjoyable.
Purple and white sweet potato varieties tend to have thinner, more tender skin than the common orange types. If you’ve found sweet potato skin tough or unpleasant in the past, trying a different variety or cooking method can make a real difference. Thin-skinned sweet potatoes that are baked until the skin crisps up barely register as “peel” at all.