US: vitamin C and stomach cancer

The latest results from the most comprehensive study of diet's role in cancer risk ever undertaken suggest that getting plenty of vitamin C may lower risk for stomach cancer. The study also indicated that vitamin C may play an important role in protecting against the specific cancer risks associated with diets high in meat.

American Institute for Cancer Research - infoZine -The study is called the European Prospective Investigation into Cancer and Nutrition, or EPIC. A cohort study initiated in 1992, EPIC is currently tracking the diets and disease rates of an unprecedented 521,483 individuals in 10 different European countries. The latest results were published in the November 11 issue of the journal Carcinogenesis.

This new study offers further evidence that people concerned about cancer risk should consume a diet that is rich in a variety of fruits and vegetables and that is also low in red meat in general and in processed meats (hot dogs, cold cuts, sausage and bacon) in particular.

Adopting this overall eating pattern ensures a steady supply of vitamin C and other natural substances such as carotenoids, retinol and tocopherol, which have all been linked to lower stomach cancer risk in previous EPIC results.

Stomach cancer, which strikes over 22,000 Americans every year, is hard to detect. Most cases are diagnosed in later stages, when symptoms develop, but by then the disease is often untreatable. This is why efforts to prevent it are so important.

Blood Levels Are Key
The new study is a nested case-control study, in which researchers select and analyze data from a subset of participants in an ongoing cohort study. In this case, they selected subjects who have developed stomach cancer (cases) over the course of the study, and compared them to subjects without stomach cancer (controls.)

The researchers examined the blood they'd sampled before the study began from 215 participants who have since been diagnosed with stomach cancer. They compared this blood to that collected from 416 controls. They then adjusted for the effects of several variables known to factor in cancer risk such as body mass index, smoking status, and H. pylori infection, in an effort to pinpoint the relationship between blood levels of vitamin C and stomach cancer risk.

They also looked at the participants' reported diets, using data gathered from questionnaires and periodic food diaries. There was no association between stomach cancer and the amount of vitamin C the subjects would get from the food they said they ate. (This lack of effect may have to do with the fact that average intake of fruits and vegetables reported by the participants was low. In fact, even those in the "highest intake" group reported eating only about 3.5 servings of fruits and vegetables per day.)

But when the researchers examined the blood levels of vitamin C (which, for certain fruits and vegetables, can provide a more accurate indication of consumption than self-reporting) they found a strong protective effect. That is: they found that those subjects with the highest level of vitamin C in their blood had a 60 percent lower risk of stomach cancer than those subjects with the lowest levels.

This protective effect was observed most strongly among those cases and controls who reported eating red and processed meats. (Red and especially processed meats contain nitrite, which can form potentially harmful carcinogens called N-nitroso compounds in the human stomach.)

Food manufacturers already add Vitamin C (in the form of ascorbic acid) to foods high in nitrite such as bacon and sausage to in an attempt to reduce the formation of N-nitroso compounds in the stomach. Getting plenty of vitamin C in the diet may add another layer of protection, this study suggests.

It's easier than you think to get enough vitamin C, even if you're not a fan of orange juice. True, citrus fruits and melons are loaded with it. But green, leafy vegetables like spinach, lettuce and kale offer plenty of vitamin C, and so do root vegetables like sweet potatoes, carrots, parsnips and yams. You'll also find vitamin C in artichokes, bell peppers, broccoli, Brussels sprouts, cabbage, cauliflower, and tomatoes.

Source: infozine.com