According to Professor Kay-Tee Khaw of Cambridge University's school of clinical medicine, the Vitamin C and many other nutrients and fibre in vegetables and fruit can protect against cancers of the lung, larynx, stomach, colon and pancreas. Of the 300,000 people who get cancer each year in the UK about a third of cases are diet-related and potentially preventable, especially bowel and stomach cancers, which claim 30,000 lives a year.
The average consumption of vegetables by Britons is just over 50kg per person annually, less than a quarter of the intake of people in Spain and Greece and less than half of the amount consumed in France and Italy. Although links between diet and cancer are not conclusive, there is a weight of evidence that suggests the combination of nutrients and fibre in vegetables can play a significant role in limiting exposure to a variety of the most common cancers.
Juliet Gray, a freelance nutritionalist, said that fruit and vegetables contained a mixture of "antioxidant" nutrients which protect the body against harmful oxidation processes. The nutrients include Vitamin C and E, beta carotene and trace minerals including selenium and zinc.
When eaten in quantities of five portions of vegetables per day, these nutrients, combined with the dietary fibre which gives vegetables their texture, can give vital protection against common cancers. Frozen vegetables are considered by the Cancer Research Campaign to be especially important, because they retain higher levels of nutrients than "fresh" vegetables which lose some Vitamin C while on supermarket shelves.