The peel often ends up in the trash before the fruit or vegetable even makes it to your plate. According to dietitian Lindsey DeSoto, this isn't always the best choice, because the outer layers of some produce contain a significant portion of the fiber, vitamins, and antioxidants.
Her list includes apples, kiwis, peaches, potatoes, watermelon, oranges, bananas, grapes, carrots, and onions. That doesn't mean all peels should be eaten raw or whole. For some produce, cooking, baking, pickling, or using grated peels is more appropriate.
Apples, Kiwis, and Peaches
In apples, peeling can remove about half of the total fiber. The skin also contains antioxidants such as quercetin. In the case of golden kiwi, eating the fruit with the skin can increase your fiber intake by about 50% compared to eating just the flesh. If the mushy texture of green kiwi is unpleasant, the skin can be wiped off with a clean cloth.
The skin of peaches is also a source of fiber and antioxidants. It contains chlorogenic acid, which has been studied for its antioxidant properties and possible effects on blood pressure and cholesterol.
Potatoes, Watermelon and Citrus
The difference in potatoes can be measurable. A baked potato with the skin contains over three times more iron and about 35% more potassium than a peeled potato. The peel also adds about 1.5 grams of fiber to a serving.
The white part between the hard green outer skin and the red flesh is the most commonly used part of watermelon. It contains fiber and citrulline and can be cooked, pickled, added to dishes, or blended into a drink.
Orange peel is edible but bitter. That's why it's usually used as grated peel. Just one tablespoon provides about 9% of your daily vitamin C needs, and it also contains fiber and plant compounds.
Bananas, grapes, carrots, and onions
Banana peels contain fiber, potassium, carotenoids, and flavonoids, but they are harder and more bitter than the fruit. They are usually cooked, baked, or added to smoothies. Red grape skins are a natural source of resveratrol, and the data on its specific effects on human health are not yet conclusive.
Carrots generally do not need to be peeled. Their outer layers contain beta-carotene and chlorogenic acid. Onion skins are rich in fiber and antioxidant compounds, and red onion skins contain anthocyanins. They can be used in making soups, sauces, and homemade broth, and then removed.
Safety remains important. The U.S. Food and Drug Administration recommends that all fruits and vegetables be washed under running water before eating or cutting. “There is no need to use soap or produce detergent”, the FDA states. Hard surfaces can be cleaned with a clean brush, and damaged areas should be cut out. Even produce that will be peeled is washed beforehand to avoid transferring dirt with the knife.
Sources: Health, Healthline