Fresh vegetables supply numerous vitamins and minerals, and provide a nutritious source of dietary fiber. Although they provide nutrients, vegetables that are members of the nightshade family of plants may contain toxic levels of certain plant alkaloids, such as solanine. Although the solanine levels in ripe nightshade vegetables seldom cause problems, consuming ones with green skins can cause a range of symptoms, including headaches.
Nightshade Vegetables
Nightshade vegetables are members of the Solanaceae family of plants. These plants have varying amounts of toxic alkaloids. The U.S. Food and Drug Administration includes tomatoes, some peppers, eggplants, tomatillos and some other plants in the FDA Poisonous Plant Database.
Solanine
Although nightshade vegetables may contain several alkaloids, solanine is the one most likely to cause symptoms of toxicity. Solanine acts as a natural pesticide, helping to protect the plants against pest infestations. This substance is toxic to both insects and animals. Among nightshade vegetables, green potatoes contain some of the highest levels of solanine. Light exposure during growth is likely to cause potato greening. Solanine is also present in toxic levels in the young sprouts and the eyes of the potatoes. Fresh, undamaged vegetables from the nightshade family are usually safe to eat.
Symptoms
Headache is one of the main symptoms of solanine poisoning. Other symptoms may include diarrhea, low body temperature, vomiting, stomach pain, paralysis and loss of sensation. The initial symptoms may appear as itching along the back of the neck and drowsiness.
Precautions
The presence of chlorophyll in a developing nightshade vegetable can signal the presence of high levels of solanine, although the chlorophyll itself does not contain toxins. Avoid eating green potatoes or old potatoes that contain numerous eyes and the beginnings of young sprouts. Other ripe vegetables within the nightshade family are usually safe to eat in moderate quantities, although you may experience a headache if you are allergic to the specific fruit or vegetable. If you experience symptoms of solanine toxicity, contact your doctor immediately.
References
- University of Nebraska Lincoln; Green Potatoes ...; Alexander D. Pavlista; 2001
- Montana State University: Are Green-Skinned Potatoes Poisonous?
- University of Maryland Medical Center: Potato Plant Poisoning
- Centre for Food Safety; Natural Toxins in Food Plants; March 2007
- U.S. Food and Drug Administration: FDA Poisonous Plant Database
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