Food plants are known to produce a wide array of chemicals. The levels of many of the more toxic ones have been reduced by hybridisation, but many of these natural toxins are still present at low levels. Eating very large amounts of one type of such foods can possibly be somewhat toxic.

Common Plant Toxins and Antinutrients

Toxins (occurrence in plant foods) - possible effect on humans and animals in large amounts:

• Cyanogenic glycosides (sweet potatoes, stone fruits, lima beans) - gastrointestinal inflammation, inhibition of cellular respiration.
• Glulcosinolates (canola, mustard, radish, cabbage, peanut, soybean, onion) - impaired metabolism, reduced iodine uptake, decreased protein digestion.
• Glycoalkaloids (potato, tomato) - depressed central nervous system, kidney inflammation, carcinogenic, birth defects, reduced iron absorption.
• Gossypol (cottonseed) - reduced iron uptake, spermicidal, carcinogenic.
• Lectins (most cereals, soybeans, other beans, potatoes) - intestinal inflammation, decreased nutrient absorption.
• Oxalate (spinach, rhubarb, tomato) - reduces solubility of calcium, iron, and zinc.
• Phenols (most fruits and vegetables, cereals, soybean, potato, tea, coffee) - destroys thiamine, raises cholesterol, estrogen-mimic.
• Coumarins (celery, parsley, parsnips, figs) - light-activated carcinogens, skin irritation.