FOOD ALLERGY: HISTORY LESSONS
Another of our cultural myths is that the past is a perfect guide to what we should eat. Hence the common criticism of ideas about food intolerance: 'Surely foods that have been eaten for thousands of years can't cause serious health problems - if they did it would have been noticed before.' In fact, experience shows that human beings are rather bad at identifying foods which cause non-acute, long-term illness. The rat, remember, only waits a day to see if a new food makes it ill. Like rats, we are programmed to notice short-term effects only.
The best illustration of this is the failure to identify wheat as a factor in coeliac disease until the 1940s. It took a famine in Holland at the end of World War II to remove wheat from the diet, and an observant doctor to recognize that his coeliac patients were miraculously cured. Similarly, the islanders of Guam have traditionally used the seeds of the false sago palm, a type of cycad, as food. Although they suffered from a high incidence of senile dementia, no-one made any connection between this and the cycad seeds. But in the 1950s an epidemic of dementia began, which continues to this day. Scientists have traced it back to the war years, when Guam was occupied by the Japanese, food was desperately scarce, and the islanders-had to rely heavily on false sago palm as a result. A constituent of the seeds has proved to be responsible for degeneration of the nerves and brain.
A third example comes from China, where a cancer survey showed an unusually high level of oesophageal cancer in one province (the oesophagus is the tube that leads from the mouth to the stomach). The local tradition of making pickled vegetables in huge vats which were left to mature for months proved to be the cause. The thick layer of mould that grew on the pickles was producing carcinogens (cancer-producing compounds) which seeped into the pickles. Even though the mould was scraped off before the pickles were eaten, enough carcinogens were there to give susceptible people cancer.
The moral of these stories is not that food in general can cause fatal diseases - the cycad seeds and mouldy pickles are extreme in that respect. The important lesson to be learned here is that history is sometimes a poor guide to diet. *24\180\8*
