A new study, part of the European Prospective Investigation into Cancer and Nutrition (EPIC), followed 521,457 subjects in 10 European countries with an average age of 52. It has been described as the largest cohort study on fruit and vegetable intake and the incidence of stomach (gastric) cancer in Western countries and the first to look at adenocarcinoma of the oesophagus. The findings indicate that garlic and onions could help protect against stomach cancer but total fruit and vegetable intake has no benefit for this disease.

These findings are quite interesting. They appear in the International Journal of Cancer (Vol. 118, pp. 2559-2566) where lead author, Carlos Gonzalez, states: “We observed no evidence of association with fresh fruit intake or with total vegetable intake, even though a protective effect of total vegetables and onion and garlic was suggested for intestinal [cancer].”
 
Usual dietary intake over the previous year was measured using a country-specific validated questionnaire. Most countries used a self-administered technique with questionnaires typically containing between 88 and 266 food items.

After an average of 6.5 years of follow-up only 400 cases of gastric cancer and 188 cases of oesophagus cancer had been reported. While total vegetable intake was not associated with a decreased risk of gastric cancer, the researchers report that a protective effect by total vegetable intake was “suggested”.

Onions have been linked to reduction in the risk of certain cancers before. US researchers recently reported that onion extracts could inhibit the growth of liver and colon cancers in vitro. In this study an increase in the intake of onions and garlic of 10 grams per day was associated with a 30 per cent (borderline significant) reduction in the risk of intestinal gastric cancer. While citrus fruit intake was also associated with negative risk of gastric cancer, the 38 per cent decrease observed was considered non-significant.

This relates to the main limitation of the study. The number of actual cases of the diseases was small, which significantly limited the statistical power of the study, even though it was such a large study. Another limitation was that fruit and vegetable consumption was relatively high, even in the lowest quartile.

It is already known that a diet containing plenty of fresh fruits and vegetables can reduce the risk of bowel and other cancers. Learning more about prevention of stomach cancer is important since it is the fourth most frequent cancer in the world with 800,000 new cases every year. It is Japan's most common form of cancer.

As Hippocrates said: "Let food be thy medicine ..."