Fruit and veg protect against pancreatic cancer: more evidence
chances of developing pancreatic cancer indicates a new
case-control study, supporting research published earlier this
The latest evidence in favor of fruit and veg comes from a study conduced at the University of California, San Francisco and due to be published in the September issue of Cancer, Epidemiology, Biomarkers and Prevention.
It involved person-to-person interviews with 2,233 people living in the San Francisco Bay Area. Of theses, 532 were pancreatic cancer patients. The remainder of the group was made up of randomly selected 'controls' who did not have pancreatic cancer, but who were of a similar age distribution, and with a similar male to female ratio, as the pancreatic cancer patients.
The participants gave details of fruit and vegetable consumption over the year preceding the interview, as well as diet, smoking, occupation, and other potentially relevant factors.
Of the vegetables eaten, onions, garlic, beans, carrots, yellow vegetables (such as yams, sweet potatoes, corn, yellow squash), dark leafy vegetables and cruciferous vegetables were seen to exert the greatest protection against the disease.
The protective benefits of light-green vegetables and tomatoes were weaker.
Citrus fruits and juices were found to be the most protective fruits, but overall fruits were seen to be significantly less protective than vegetables.
Participants who ate at least five serving of the protective vegetables or vegetables and fruits per day were seen to have a 50 percent reduced risk of pancreatic cancer, compared to those eating just two servings a day.
Those eating nine servings per day of vegetables and fruit halved their risk compared to those eating anything less than five servings a day.
The Dietary Guidelines for Americans, published in January 2005, recommend that Americans consume two cups of fruit and two and a half cups of vegetables per day, for a reference 2000 calorie per day diet. They also advise balancing intake of each of five groups (dark green, orange, legumes, starchy and other vegetables) over the course of the week.
"Pancreatic cancer is not nearly as common as breast or lung cancer, but its diagnosis and treatment are particularly difficult," said senior author Elizabeth Holly, professor of epidemiology and biostatistics at UCSF.
The American Cancer Society predicts that 32,180 new cases of pancreatic cancer will be diagnosed in the US in 2005, and that 31,800 Americans will die of the disease. It is a particularly virulent form of the cancer, with a five-year survival rate of under four percent.
"Finding strong confirmation that simple life choices can provide significant protection from pancreatic cancer may be one of the most practical ways to reduce the incidence of this dreadful disease," said Holly.
Although the authors say that, given the size and design of the study, the likelihood of the results being down to chance was less than one in a thousand for many vegetable categories, they did say that the way foods are prepared may be a factor.
For example, raw vegetables may be more protective, and fried potatoes less protective than tubers prepared in other ways.
"With more follow-up, such studies will be able to examine this question more rigorously," said June Chan, assistant professor of epidemiology and biostatistics at UCSF and lead author.
"In the meantime, results from case-control studies like this one provide support for the hypothesis that vegetables and fruit provide some benefit in protecting against the development of pancreatic cancer."
The UCSF research some support to the findings of another study, published in the May issue of the International Journal of Cancer (vol 114, issue 5, pp817-23).
This reported that men with the highest overall fruit and vegetable intakes are about half as likely to develop pancreatic cancer as those with the lowest intakes, but there was no clear association between diet and pancreatic cancer risk among women.
However the same researchers, from the University of Montreal, published another study in the March issue of the Journal of Nutrition, indicating that the tomato compound lycopene is, indeed, beneficial in protecting against the disease in men.
Lycopene's putative protection against pancreative cancer forms part of a health claims petition submitted to the FDA last year by American Longevity. The administration has yet to give a decision as to whether it approves the claim, following a number of delays.