are destroyed or removed by normal preparation procedures such as
soaking and cooking. Even so, red kidney beans are still responsible for
occasional outbreaks of food poisoning when they have been insuffi-
ciently cooked to destroy the lectins they contain. Lathyrism is a more
serious condition associated with a toxin in the pulseLathyrus sativa
which can be a major food item in North African and Asian communities
during times of famine. In favism, an enzyme deficiency predisposes
certain individuals to illness caused by glycosides in the broad bean,
Vicia faba.
To some extent toxic or antinutritional characteristics can be bred out
of cultivars intended for human consumption, although the problem
cannot be eliminated completely. For affluent consumers in the devel-
oped world, particularly toxic foods can be avoided since alternatives are
normally available in plenty. This is not always the case in poorer
countries where these diet-related conditions are far more common.
It is however important to keep a sense of proportion in this. Eating
inevitably exposes us to natural chemicals whose long-term effects on
health are not known at present. Provided such foods form part of a
balanced diet and are correctly prepared, the risks involved are generally
acceptable, particularly when compared to the certain outcome should
immoderate fear of food lead to complete abstinence.
In addition to the hazards posed by natural toxins that are an intrinsic
feature of their composition, foods may also act as the vehicle by which
Figure 6.1 Some natural food toxicants
Chapter 6 159