Antioxidants Linked with Lower Risk of Pancreatic Cancer

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People whose diets include high amounts of vitamins C and E and the mineral selenium may have a lower risk of pancreatic cancer, according to a new study from England.

Participants in the study with the highest intake of all three of these compounds were 67 percent less likely to develop pancreatic cancer over a 10-year period compared with the people who had the lowest intakes, according to the study.

The decreased risk might be explained by the fact that vitamins C, E, and selenium are antioxidants, which combat free oxygen radicals that can damage DNA, the researchers said.

"Smoking and diabetes, which are established risk factors for pancreatic cancer, induce oxidative stress and free radical production," they wrote in their study, published online Monday (July 23) in the journal Gut.

The researchers found an association, not a cause-and-effect link, and more work is needed to confirm the results.

If a causal link between these compounds and pancreatic cancer was found, the findings suggest that intake of these vitamins and selenium could prevent one in 12 cases of pancreatic cancer, the researchers said.

Pancreatic cancer and antioxidants

Pancreatic cancer is a deadly disease. An estimated 44,000 people in the U.S. will be diagnosed with pancreatic cancer in 2012, and 37,000 will die of the disease this year,according to the National Cancer Institute. 

In the study, researchers gathered data from 24,000 people between ages 40 and 74 in the U.K. who enrolled in a study called the EPIC-Norfolk Study between 1993 and 1997. Participants completed questionnaires about their medical histories, gave blood samples and kept food diaries for a week.

The researchers used the food diaries to estimate participants' intakes of vitamin E and selenium; vitamin C levels were measured using the blood samples.  

Over 10 years, 49 participants developed pancreatic cancer. The researchers compared the nutrient intakes of the cancer patients with those of 4,000 healthy people.

The researchers found that the link between pancreatic cancer and people's intake of selenium and vitamin E showed what's known as a "threshold effect," meaning that it was only the people who had the lowest intake — below a certain threshold — who had an increased risk of pancreatic cancer.

For example, the researchers divided people into four equal groups based on their intake of selenium. People in the lowest quartile had about twice the risk of developing pancreatic cancer as people in any of the top three quartiles.

Similarly, for vitamin E, people in the lowest quartile were 43 percent more likely to develop pancreatic cancer compared with those in the top three quartiles.

For vitamin C, the researchers found a generally decreasing risk of pancreatic cancer with increased levels.

Antioxidants and cancer

People in the study in the lowest quartile of vitamin E intake were getting less than 7.2 milligrams per day; U.S. guidelines recommend adults consume 15 milligrams per day.

A recent study also showed that most people in the U.S. get plenty of selenium from their diets, and don't need supplements. The foods with the highest concentrations of selenium are organ meats and seafood, but the mineral is also found in cereals and grains, muscle meats and, to a lesser extent, dairy products, fruit and vegetables.

"The potential benefit of these micronutrients is only applicable to those with the lowest intakes," the researchers wrote. In other words, only people who are deficient in these compounds are likely to see their risk of pancreatic cancer decrease by raising their intake.

But the findings support further research into how antioxidants may benefit health and boost the immune system, they said.

Previous trials looking at the effects of antioxidant supplements on pancreatic cancer risk have produced mixed findings, and one reason for the results seen in this study may be that food sources of these nutrients have different effects on the body than nutrient supplements, the researchers said.

Pass it on: Diets that include high amounts of vitamins C and E and the mineral selenium are linked with a lower risk of pancreatic cancer, a new study finds.

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