Potatoes get mixed reviews from nutritionists; some claim that potatoes are good sources of a variety of vitamins, while others suggest that the carbohydrate load of a potato is far too high, and they can cause blood sugar instability. Nutritional debates aside, potatoes are an excellent source of energy from carbohydrate.
Potato Nutrition
While potatoes vary with regard to nutrient content depending upon the type of potato, a typical potato -- one that weighs around 5 oz -- provides 110 calories of energy. The vast majority of this comes in the form of carbohydrate. Potatoes contain no fat, and very little protein -- only about 2 g. A typical potato contains only about 2 g of fiber.
Carbohydrates in the Body
When you eat carbohydrate, you're taking in the chemical amylose, which is made up of long chains of glucose molecules. Digestive enzymes in your gut break the amylose into glucose, which you absorb into the bloodstream, and which your cells can then use for energy. While most body cells can use digestion products of carbohydrates, proteins or fat for energy, some body cells -- including brain cells and certain muscle cells -- use glucose preferentially.
Energy from Food
Any food that contains calories provides energy -- carbohydrates, proteins and fats are all sources of energy. However, the body tightly regulates glucose in the bloodstream, because this special source of energy is so important to the brain in particular. When you eat very little carbohydrate, you can feel mentally fatigued and slow, while eating plenty of carbohydrate helps keep your mind sharp. Overeating carbohydrate doesn't improve brain function, however -- more carbohydrate than you need is simply stored as fat. Since potatoes contain lots of carbohydrate, they help provide the glucose your brain needs.
Glycemic Index
One important consideration with regard to potatoes and energy is that they have a high glycemic index. This is a measure of how quickly the glucose from a potato gets into the bloodstream. According to the Linus Pauling Institute, a potato's glucose takes only slightly longer to reach the bloodstream than glucose from pure sugar. If you're exercising, this is a good thing -- you want sugar entering the bloodstream quickly. If you're not exercising, however, you may want to limit potato consumption to help maintain stable blood sugar, or at least consume potatoes in combination with protein -- the protein helps slow glucose absorption.
Vitamin B
In addition to containing energy from carbohydrate, potatoes contain several of the B-vitamins, which you need in order to process the nutrients you get from food. While B-vitamins don't provide energy directly, getting enough B-vitamins in your diet ensures that you can utilize the nutrients you take in. In particular, potatoes are sources of vitamin B6, which your cells use to help release stored glucose from the liver into the bloodstream.
References
- "Biochemistry"; Reginald Garrett, Ph.D. and Charles Grisham, Ph.D.; 2007
- Linus Pauling Institute: Glycemic Index
- MyPlate
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