Ask a Dietitian

As seen on BCTV September 21/99

SOLANINE: THAT GREEN STUFF UNDER THE SKIN OF A POTATO

There are certain toxicants or poisons that can naturally occur in food. Solanine, part of a group of compounds known as alkaloids, is one such substance. Solanine contains TGA – total glycoalkaloids. These are studied more than other toxicants because they are commonly found in potatoes – that green stuff just below a potato skin.

At a level of 10 mg or less per 100 grams – the TGA’s would not alter the taste of a potato. More than this amount would cause a bitter taste. In excessive amounts a burning sensation would be experienced.

Solanine forms when potatoes have been:

• exposed to too much light in cold conditions
• mechanically injured
• exposure to temperatures above 10 degrees Celcius during storage
• left to become too old
• allowed to sprout

Ingesting potatoes containing solanine may cause nausea, vomitting or stomach cramps but is not fatal in humans. It can be more of a concern with livestock eating old potatoes or potato peelings. 100 pounds of potatoes/year could provide 10,000 mg of solanine – a lethal dose if consumed all at once.

These substances are not destroyed by cooking. Therefore, peel potatoes if necessary to minimize solanine intake. If not necessary, don’t peel the potato. Many of the nutrients are just below the skin surface.

Don’t avoid potatoes as they remain a quick, cheap, but quality vegetable option supplying vitamins C, B6, potassium and other nutrients. Potatoes are not fattening unless deep fried or slathered in butter and cream. Store potatoes in a cool, dark place but not in the fridge. They also prefer to be stored away from onions.

Watch for the Eating for Energy segment every Tuesday on BCTV’s Noon News Hour!

Article written by Patricia Chuey and reprinted with permission