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Toxicity of Potato Skins Becomes a Hot Issue : Natural Chemicals in Peels Can Pose Problems If Eaten in Huge Quantities

June 25, 1987|ROSE DOSTI | Times Staff Writer

"Potato Skins Contain Natural Chemicals Toxic to Humans, Cornell Study Says," read the headline on the university news service release that was picked up by the media coast to coast.

Hey, what's happening here?

It was just a simple research project measuring the effect of boiling on chemical compounds known as glycoalkaloids and phenols naturally present in the cortex region of potatoes. But when Cornell University graduate student Barry Gosselin reported that toxic chemical compounds found naturally in potatoes may be hazardous to health if eaten in large amounts, the press, it seems, read more in the spud report than the researchers intended. Gosselin authored the Cornell University research project directed by expert potato biochemist Nell Mondy, and reported the findings at a meeting of the Institute of Food Technologists in Las Vegas last Thursday.

The study found that consuming large amounts (more than 20 milligrams per 100 grams of fresh weight) of a group of the chemical compounds naturally present in potatoes could cause headaches, nausea and diarrhea. What the study did not state was the exact amount of potatoes one would need to eat to make a person sick.

When pressed, Gosselin estimated that consuming 10 to 50 potatoes at one sitting would do it. Mondy had noted in an interview reported in the Cornell University release that the variety of the potato, how much light and heat potatoes receive after harvest, weight and size of the potato and body weight of the individual eating the potato made it difficult to determine "categorically" just how many potatoes someone would have to eat in order to suffer ill effects.

"We were simply looking at the effect of boiling on compounds present in potatoes. Some work had been done on baking and frying, but not yet on boiling. Our basic message was to make people aware that toxic compounds exist in certain amounts and that they should peel potatoes before boiling. We had hoped that the press would take it as caution, not an alarm. We're telling people to tone it down," said Gosselin when reached by telephone.

Effects of the report's budding impact on the public brought a quiver or two in the voices of the potato industry persons contacted for comments.

"The story hasn't affected the potato industry yet, but it could--not that we expect it to," said Bob Mercer, president of the Potato Board, the promotional arm of the potato industry.

Mercer said that skins of potatoes are no worse or better than several other plant foods in their toxicity potential. "It can become worse when potatoes turn green from exposure to light. Direct light causes chlorophyll buildup. The tuber after all is a modified stem so when light enters, it turns green and builds chlorophyll, a bitter-tasting substance. There is a relationship between light and chlorophyll and it does affect the increase of alkaloid, which is poisonous. But you would have to have quite a buildup to have a negative effect. The bitterness alone will cause anyone--even cows--to spit it out," Mercer said.

"It makes me very sensitive when the press hits on something as basic as potatoes. That's the bread and butter for farmers here. It's our livelihood that's affected," said Kathy Johnson, promotion director of the Red River Valley Potato Growers Assn. in East Grand Forks, Me., where 58% of the crop goes into making potato chips, many of them with skins.

Flinched at the News

Even nutritionists, such as registered dietitian Rita Storey, the media spokeswoman for the American Dietetic Assn., flinched at the news. "Oh dear, this news really flies in the face of what we've been telling people to do--to eat the skin because it is an excellent source of fiber, complex carbohydrates, vitamin and minerals, not to mention the increased concentration of Vitamin C near the skin."

Agricultural Extension (UC Davis) vegetable specialist Vincent Rubatzky Ph.D. in the vegetable crops department explained that toxicity may affect people differently. "Some people may get a headache without realizing where it stems from after eating only one bad potato. For others it would take dozens to make them sick. It's a personal characteristic," he said.

According to Gosselin, some deaths due to toxic potato consumption were reported in Germany during the '20s and '30s when victims were said to have eaten heavily sprouted potatoes. Potato sprouts contain high levels of glycoalkaloids. Suffering due to green potato consumption by German soldiers also was reported during World War II.

What's a body to do?

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