Vitamin C intake offers protection against stomach cancer

The study also shows that lycopene, an antioxidant found in tomatoes, could have a protective effect against the cancer although the researchers caution that this needs further research.

The team from the US National Cancer Institute and National Public Health Institute of Finland assessed the association between fruit and vegetable consumption and the risk of stomach cancer in approximately 29,000 male smoker participants, aged 50 to 69, of the Alpha-Tocopherol, Beta Carotene (ATBC) cancer prevention study in Finland.

This trial, initiated to test the effect of vitamin supplementation on the prevention of lung and other cancers, ended in 1993 but ongoing follow-up of the participants continues, offering new insights into the causes and prevention of multiple diseases.

Speaking yesterday at this year's Frontiers in Cancer Prevention Research​ conference (abstract 173), the US and Finnish scientists said they had found fruit and vitamin C intake, but not vegetable consumption, reduced risk of non-cardia cancer approximately 45 per cent.

Non-cardia cancer is the major form of stomach cancer in most parts of the world. Stomach cancer is the second most frequent cause of cancer deaths worldwide, with an estimated 776,000 deaths in 1996, and the fourth most common cancer. In the UK stomach cancer is the sixth most common cancer with 10,000 new cases each year.

"Since our findings are similar to the results found in several other studies, fruit and vitamin C intake are likely to be useful for the prevention of stomach cancer,"​ said Farin Kamangar of the Cancer Prevention Studies Branch at the National Cancer Institute, and one of the lead investigators of the study.

Last year researchers at the San Francisco VA Medical Center found that the lower the level of vitamin C in the blood the more likely a person will become infected by Helicobacter pylori​, the bacteria that can cause peptic ulcers and stomach cancer. Although it was not clear whether the presence of the bacteria lowered blood levels of the vitamin, or whether vitamin C levels could protect against it, other studies have also seen low blood levels of vitamin C in people with the cancer.

In Japan, where rates of the cancer are much higher than in the west, researchers have linked a diet of highly salted food containing little vitamin C, with a twofold risk of the cancer.

Another component of fruit, lycopene, which is already associated with reduction of breast and prostate cancer risk, also appeared to lower chances of stomach cancer by 34 per cent.

But the effect of lycopene on gastric cancer "needs further studies"​, warned Dr Kamangar.

Recent research suggests that lycopene may reduce risk of cancer by activating special cancer preventive enzymes, rather than through its antioxidant effect.

When looking at cardia cancer (another part of the stomach), consumption of retinol, a form of vitamin A, was associated with a reduced risk, but the vitamin E forms alpha-tocopherol and gamma-tocopherol seemed to be associated with an increased risk, reported the researchers.