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The last supermarket potatoes (yellow potatoes) [that I purchased]... when I peeled them had a green layer just underneath the skin. I remember reading a long time ago that it is harmful. Could you please address this for me?
Storing potatoes in the light encourages chlorophyll production just under the skin. Unfortunately, the process can also result in a buildup of solanine. This natural alkaloid is not life threatening, but consuming solanine can cause side effects including gastrointestinal distress, nausea, headaches, and fatigue. The chlorophyll and solanine production appears to occur more readily in waxy potatoes as well as those with light skins.
I store my potatoes in a dark, cool place as it retards this process and also keeps sprouts from forming. They will remain fresh longer also.
Although it would take a fair amount of solanine to cause illness, it's a good idea to peel the potato and discard the skin and the green layer under the skin. The potatoes will then be safe to eat.
Thanks for writing,
Timothy S. Harlan, MD, FACP