Friday, April 17, 2009

Killer Tomatoes

My grandmother was 97 when she died and she died while sitting in a chair watching TV at her home. Earlier in the day she had gone for a helicopter ride. I don’t remember her ever spending a day in hospital except for giving birth to her ten children.

My colleague told me the other day that he once ate a feijoa and soon after fell to the ground, unconscious.

What is the relationship between these two stories?

We all used to dread a little bit going to my grandparents house as they would always try and feed us the most over-cooked foods and concocted meals from whatever was left over in the fridge and you never where sure how long it had been there. Yet they never seemed to get sick. Vegetables were always cooked thoroughly . It was a time when people were starting to eat everything raw or only lightly steamed even going so far as to eat raw mushrooms. Would my grandmother have lived longer if she ate more salads? I don’t think so.

All fruits and vegetables contain natural toxins and these toxins are mostly neutralized by cooking. The more cooking the better. Cooking also kills bugs and bacteria, the sort of thing likely to be found on mushrooms that grow in dark dirty places. People think they can wash vegetables and that this will be good enough but tests show even thorough washing is ineffective. Lettuce leaves simply cannot be washed to a point where they are safe to eat and this goes for all raw food especially mushrooms. As well as bugs there are also man made pesticides and herbicides to contend with. Yet long before man came along nature had already developed its own insecticides and even herbicides. It makes sense that the skins of fruit, leaves and bark have developed defences against predation. The main attackers are insects and fungus and because plants cannot physically fight back they have developed static defences by using toxins, hard shells and thorns to dissuade predation. Believe it or not it is mostly not in the best interests of a plant to be eaten and so evolution has provided ways to make it more difficult.

Some good has come of this and many of our medicines are derived from plant sources. This has been a happy coincidence, so often seen in evolution, where something has been developed for a specific purpose like poisoning or repelling insects and has later turned out to be a good drug for the treatment of human maladies. Yet while medicines are a good thing the healthy body shouldn’t take medicine if it doesn’t need to. Peeling, soaking, fermenting and cooking of vegetables has long been known to render it edible. Some things are downright poisonous if prepared in the wrong way and I contend that this is the case for most vegetable matter. Perhaps some things are ok, like nuts that defend themselves with hard outer shells or fruits that want their seeds to be dispersed by mammals. In general it is the skin of the fruit that is poisonous and this makes sense as this is the thing that was developed to protect the seeds and the food that surrounds the seeds.

So my colleague fell down after eating the feijoa because he ate the flesh close to he skin and he was particularly susceptible to the Methyl Benzoate that feijoa skin contains. My grandmother living almost a century was possibly partly due to thorough sterilizing and detoxifying of plant food – it certainly didn’t do any harm.

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