More evidence that fish prevents prostate cancer

Canadian researchers report that men who eat fish several times a week may protect themselves from prostate cancer, while men who eat meat, ham or sausage 5 times a week may have a 3-fold increased risk of prostate cancer. These findings add to a growing body of evidence suggesting a relationship between diet and prostate cancer risk.

"Many studies have suggested that nutritional factors may affect prostate cancer development," says Armen Aprikian, MD. of the urology division McGill University Health Centre, Montréal, Que. " The aim of our study was to evaluate the relationship between dietary habits and prostate cancer detection."

He and his team studied studied 917 men who underwent biopsy because of elevated PSA level, rising PSA or abnormal digital rectal examination. Before receiving the results of their biopsy, all patients answered a self-administered food frequency questionnaire.

"The incidence and mortality rates of prostate cancer," Dr. Aprikian writes, "vary widely among countries":

The lowest prostate cancer incidence and mortality rates are observed in the Far East and on the Indian subcontinent, and the highest rates occur in western Europe, Australia and North America, with up to a 30-fold variation between highest and lowest rates.

Interestingly, there are differences within the same ethnic groups, such as Japanese living in the United States, who have a 4–5 times higher incidence of prostate cancer than those living in Japan.

Environmental and lifestyle factors, including dietary habits, are suggested as determinants. Total energy intake, fat intake, especially of animal sources, and dairy products and calcium have been associated with a positive risk.

Among fruits and vegetables with suggested protective effects are tomatoes and yellow-orange and cruciferous vegetables, although other studies have not shown this association. A fish diet, with its unique marine omega-3 polyunsaturated fatty acids, has been suggested by some studies to protect against prostate cancer although others have found no association. We studied the association between different dietary items and the detection of prostate cancer in a cohort of high-risk men.

Of more than thirteen hundred male patients who were scheduled for biopsy due to high risk of prostate cancer, some nine hundred to fill out the questionnaires, which covered a range of life-style and prostate related issues in addition to food factors.

The men were asked about food frequency, age, marital status, ethnicity, occupation and level of education, smoking habits, alcohol intake, family history of prostate cancer, medical history of general diseases (e.g., diabetes mellitus, liver diseases, heart diseases and arthritis) and local genitourinary conditions (e.g., cystitis, prostatitis, sexually transmitted infections and vasectomy).

How Fish Eaters' Risk Compares to Meat Eaters'

The association of a meat-heavy diet prostate with cancer was statistically significant, and so was the association of lower prostate cancer risk with fish-eating. In this group of 900 men who were already showed signs of prostate problems, men who ate red meat or meat products almost every day -- 5 times a week -- were 3 times likelier than average actually to have prostate cancer.

Men at risk who ate fish 4  times a  week were half as likely as average to have prostate cancer.

A number of previous studies, Dr. Aprokian notes, have linked lower risk of prostate cancer development with fish or with "the specific fatty acids as marine omega-3 polyunsaturated fatty acids and omega-6 polyunsaturated fatty acids present in animal sources." These studies suggest that "omega-3 polyunsaturated fatty acids may protect against prostate cancer, whereas omega-6 polyunsaturated fatty acids stimulate malignant cell growth," he says, which may explain his team's findings.

More surprising, neither the McGill team nor another recent study found any correlation with fruit and vegetable consumption. "Although there exists some evidence of the protective effect of tomatoes and green vegetables against prostate cancer," Dr. Aprokian says, "we did not find any statistically significant association between those types of food with prostate cancer."

They found unexpected hints (not quite statistically significant) of a protective effect from potatoes compared with higher risk for those who ate other forms of starch (bread and rice). Possibly, Aprokian says, "the apparently protective effect of potatoes is due to other associated dietary habits."

The full text of this study is online :

wild salmon jumps upstream
Wild salmon returning home to spawn

Dietary habits and prostate cancer detection: a case–control study

Moamen Amin, MD, Suganthiny Jeyaganth, MSc, Nader Fahmy, MD, Louis R. Bégin, MD, Samuel Aronson, MD, Stephen Jacobson, MD, Simon Tanguay, MD, Wassim Kassouf, MD, and Armen Aprikian, MD

Can Urol Assoc J. 2008 October; 2(5): 510–515.
Editorial:

Weighing the data on diet and prostate cancer

Alexandre Zlotta, MD, PhD, FRCSC


Last year a Swedish study, Salmon, Prostate Cancer and a COX-2 gene variant, suggested that salmon is especially protective against prostate cancer for men who have one specific, common variation in a single gene.

We've restored the "lost" page of recipes for Wild Alaska Canned Salmon (one of the least costly ways to buy the wild fish), including some from chef Hughie Kearnley in Glasgow.