However, skin does keep vitamins from being boiled off during cooking. A baked potato with skin intact has almost all its original vitamin C, whereas a potato that has been peeled and boiled retains only 50-80 percent. (There's even less if the potatoes have been mashed up and left to sit around for a while.)
So, just leave the potato skins on while cooking and peel them afterward, right? Not so fast.
Potato skins contain toxic compounds called glycoalkaloids that can cause headaches, nausea, and diarrhea if eaten in sufficiently large amounts. Researchers Nell Mondy and Barry Gosselin of Cornell say boiling potatoes in their skins can cause the toxins to migrate into the vegetables' flesh.
Things get a little simpler when we turn to other fruits and vegetables. Skin is a good source of dietary fiber, something most Americans could use a lot more of.
One medium apple with peel, for instance, contains about 3.3 grams of fiber, while a peeled apple contains only 1.5 grams. Although there are no official daily fiber requirements, authorities say most people get only 10-20 grams per day, even though they could use 20-35.
There are several types of dietary fiber. The one abundant in apples, and to some extent in all fruits and vegetables, is called pectin. It's water soluble, and water-soluble fiber has been shown to reduce blood cholesterol levels.
What happens apparently is that each particle of fiber grabs an armful of bile salts on its way through the intestine (a process called "binding") and carries it out of the body during excretion.
The body then has to make new bile salts and evidently uses cholesterol as the raw material, thus keeping the blood cholesterol level down.
It has not been conclusively shown that an apple a day keeps the heart specialist away, which is to say they haven't proved that eating apples and other pectin-rich fruits and vegetables reduces heart disease. It's also true that if you eat too much water-soluble fiber it'll bind with (and subsequently carry away) micronutrients your body needs.
But since most people could stand to double their dietary fiber intake, it's probably a good idea to leave your apples and other fruits and vegetables (except taters) unpeeled ... unless of course the whole idea just grosses you out of existence.
Nutritionists would rather have you peel your veggies and at least get the benefit of the complex carbohydrates and starches than not peel and consequently not eat them at all.
Това е - ако някой не разбира - ще превеждам.