As the old adage says, ‘we are what we eat’, and there is certainly an increasing public awareness of the overwhelming significance of diet in the development of many diseases. For instance, it has been shown that heart disease is linked to the consumption of animal fat, and colorectal cancer to diets that are low in fibre. Both of these diseases, which are associated with the modern high-fat, low-fibre Western diet, are virtually unknown in the rural Third World.
It has been known for the last 20 years that prostate cancer has a significant dietary basis. Indeed, there may be additional protection against cancer from specific diets. The China study has shown that consumers of diets that are rich in yellow beans are further protected from the development of prostate cancer. The reduction in risk is nearly five fold, and so very important. In 1999, an exhaustive prospective study of dietary risk factors was published. Called the Netherlands Cohorts Study, this was an analysis of the diets and medical fates of over 56,000 men. The men, aged between 55 and 69 years, were followed over a period of nearly seven years and during this time assessments made of what they ate. During the period of the study 642 men (1.5%) developed prostate cancer. Those who had consumed significant amounts of cured meat and milk products were at much greater risk of developing prostate cancer.
There is overwhelming statistical evidence that cancer occurs at half the rate in vegetarians that it does in meat-eating omnivores. However, it is not known whether this is due to additives such as preservatives, antibiotics and colouring agents or whether it is the consumption of meat itself which is the cause. It is thought that a group of chemicals called phyto-oestrogens, which are female hormone-like chemicals present in plants, are responsible for the protective effect of a vegetarian diet. It may well be that all that is required in this matter is a little sense, and sense quite remarkably fits with the UK Government’s health guidelines recommendation that we consume at least five portions of fruit and vegetables daily.
In the context of the relationship between diet and cancer, it has been known for some time that people from the Mediterranean region are much less likely to develop prostate cancer than other Europeans. The reason for this would appear to be that their diets are rich in processed tomato products of the sort used in pizzas and pasta sauces. It is clear that only cooked tomatoes are protective, and the active ingredient that confers this protective effect would appear to be an agent called lycopene. Lycopene appears in tomatoes only as a result of cooking, the process changing the chemical nature of tomatoes.
Certainly, pursuing a diet of pizza and pasta would seem to be a most pleasant way of reducing the risk of developing prostate cancer. However, it is not clear how long you have to be on such a diet to increase your protection against getting prostate cancer. The Heinz Corporation, which buys up 80% of the world’s production of tomatoes, was enormously interested in these observations, unique evidence of the militaryindustrial complex having a positive health benefit!
A number of studies have analysed the importance of trace elements such as zinc and selenium in the prevention of many cancers. The results would appear to suggest that there is a minor role for these elements in protecting against prostate cancer, but as yet it is unclear quite how significant this is. There is very little evidence that a normal diet is deficient in these trace elements, although some dietary pundits will comment that conventionally accepted standards are suboptimal assessments of requirements.
