It is common to hear that the scar-like bumps, or "eyes," on potatoes are poisonous or toxic. The Idaho Potato Commission reports that potato eyes are safe to eat, but other sources, such as the Michigan State University's Food Domain, disagree. Understanding what causes the eye of the potato and its natural toxins should help you to make your own decision.
What Is a Potato, Anyway?
Potatoes are often called "roots" because they grow underground, but they are actually shoots, or tubers. Shoots usually grow above ground and the leaves use sunlight for photosynthesis, but potato plants are specialized to make shoots below ground and convert sugar into starch as the shoot swells.
How the "Eyes" Get on Potatoes
The eyes of potatoes are nodes or the remnants of little, scaly leaves. The small leaf erodes as the potato grows and leaves a little scar that becomes the eye.
Toxin in Foods
Potatoes are part of the nightshade family. Nightshades contain a naturally-occurring alkaloid called solanine, which is toxic chemical. When a potato is exposed to light, solanine is produced. As a potato ages, solanine levels increase. When potatoes get exposed to too much light, they starts to turn green, a good indication of elevated solanine levels. The Michigan State University's Food Domain warns against eating potato eyes because they contain a high concentration of solanine.
How Much Solanine Makes a Potato Poisonous
Twenty to 25 mg is the toxic level of solanine, according to the U.S. Food and Drug Administration. A healthy potato contains approximately 8 mg of solanine in a 100 g potato. Age and light affect the amount of solanine in the potato and the eyes. To avoid the toxin and put your mind at ease, a simple solution is to remove the eyes and cut away any green that is on your potatoes.
Additional Considerations
The Idaho Potato Commission suggests that you do not purchase damaged potatoes with cuts, cracks, discoloration or decay. In addition to the elevated solanine, once a potato turns green, it tastes bitter.
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