Higher levels of the essential amino acid methionine in the diet is apparently associated with a reduction in pancreatic cancer risk, according to the findings of a large study conducted in Sweden.

Previous studies have shown that alterations in the methyl group metabolism may contribute to pancreatic diseases, including pancreatic cancer, the authors explain, suggesting that methyl group donors like methionine could influence the risk of pancreatic cancer.

Dr. Susanna C. Larsson from the Karolinska Institute, Stockholm, and associates examined the dietary levels of methionine and vitamin B6, along with the pancreatic cancer rates in two large studies - Swedish Mammography Cohort and Cohort of Swedish Men. This comprised nearly 82,000 men and women ages 45 to 83 years.

During an average follow-up of 7 years, 147 cases of pancreatic cancer were diagnosed. The risk of pancreatic cancer was 56 percent lower for individuals with the highest levels of methionine in the diet compared with those with the lowest levels, the researchers found.

The inverse association between methionine levels and pancreatic cancer was more pronounced in smokers than nonsmokers, they add, but there was no interaction between the amounts of alcohol consumed or dietary levels of methionine and pancreatic cancer risk.

There was no significant association between vitamin B6 intake and pancreatic cancer risk, the investigators report in the medical journal Gastroenterology.

“Foods rich in methionine include fish, poultry, meat, legumes, and dairy products,” they add.

“The results could be important because pancreatic cancer, now the fourth most common cause of cancer mortality in the United States, has an extremely high mortality rate,” write Dr. Albert B. Lowenfels and Dr. Patrick Maisonneuve from New York Medical College, Valhalla, in a related editorial.

Even though the authors factored in the possible effects of other known pancreatic cancer risk factors, the editorialists continue, it is still possible that this apparent protective effect of methionine actually involves another dietary or nondietary protective factor.

Lowenfels and Maisonneuve conclude: “Before suggesting that our patients increase their intake of methionine, we need substantial additional data concerning efficacy and safety issues.”

SOURCE: Gastroenterology, January 2007.