Antioxidants may lower pancreatic cancer risk

Eating more foods rich in antioxidant nutrients like vitamins C and E and selenium may reduce the risk of pancreatic cancer by up to two thirds, suggests a new British study. It used data from the Norfolk arm of the European Prospective Investigation of Cancer (EPIC) study.

The prospective observational trial, lead by Dr Andrew Hart of the University of East Anglia, was, however, only able to suggest an association, not a cause and effect relationship. Nonetheless the researchers claim that if further research confirms a direct link, this type of diet could prevent 8% of pancreatic cancer cases. The disease kills more than 250,000 people worldwide every year and has the worst prognosis of any type of cancer, with just 3% of people surviving beyond 5 years.

The team of scientists tracked the long-term health of 23,658 people aged 40 to 74, who entered the study between 1993 and 1997. Each participant submitted a comprehensive food diary, detailing the types and amount of every food they ate for seven days, as well as the methods they used to prepare it. The 7-day food diary is considered to be the most accurate method of measuring diets in large-scale epidemiological studies. Each entry was then matched to one of 11,000 food items, and the nutrient values calculated using a specially designed computer programme (DINER). Vitamin C was measured through serum samples.

After 10 years, 49 participants (55 % of whom were male) had developed pancreatic cancer. By 2010, the number of participants diagnosed with pancreatic cancer increased to 86 (44 % were male). On average, the cancer patients lived for another 6 months after diagnosis. The patients were compared with a control group of 3,970 participants who did not have pancreatic cancer.

The cancer patients and the control group were separated into quartiles for intake of vitamin C, vitamin E, selenium, and zinc. Those who were in the highest three quartiles for the intake of vitamins C and E and selenium were 67% less at risk of pancreatic cancer compared to participants in the quartile with the lowest intake of these antioxidants.

The researchers found that the link between pancreatic cancer and people's intake of selenium and vitamin E showed 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.

1. Banim P.J.R. et al. Dietary antioxidants and the etiology of pancreatic cancer: A cohort study using data from food diaries and biomarkers. Gut 2012; doi:10.1136/gutnjl-2011-301908.