The table below lists a few families of the more common plant toxins found at very low levels in the foods we eat. Many of these compounds are known carcinogens. Different varieties of the same plant species can also have different levels of toxins and nutritional value. Effect on humans and animals is based on laboratory tests using toxin concentrations much higher than the concentrations normally found in food. For example, phytate, a common component of most seeds and cereals, forms a complex with many important minerals, making less of the minerals available.
Many plants carry naturally-occurring DNA fragments called transposable elements .
Unlike GE plants, new varieties of conventionally-bred crops are generally not evaluated for toxin levels before they are marketed. But in all likelihood the standards do not represent the natural range of toxin levels actually present in conventional foods. In most cases, the GE variety fell within the range of toxin levels observed in conventional varieties, and differences between the same plant variety grown in different locations were much larger than the differences between GE and non-GE varieties. There were also a few cases of incomplete or missing toxicity data. In a nutshell Food plants are known to produce a wide array of chemicals and, although the levels of many of the more toxic ones have been reduced in the process of domestication, many of these natural toxins are still present.