January 22, 2007

Diet may be to blame for Jamaicans' high prostate cancer risk

Jamaican men may have the world's highest rate of prostate cancer in part because their diet contains a relatively large amount of the ω6 polyunsaturated fatty acid (PUFA) linoleic acid (LA), say researchers.

"Despite sharing a common genetic ancestry with Black Americans, the incidence of prostate cancer is significantly higher in Jamaicans," explain co-author Chad Ritch (University of Chicago, Illinois, USA) and team.

They add: "The difference in incidence suggests that an environmental etiology may account for the observed variation."

Although Ritch and colleagues acknowledge in the Journal of Urology that the impact of diet on prostate cancer risk is controversial, they note that previous in vitro and in vivo studies have suggested that fatty acid intake can affect prostate cancer risk.

"Interestingly, the [Jamaican] diet is rich in the ω6 PUFA LA in the form of the ackee fruit, which is indigenous to Jamaica and most widely consumed there," explains the team.

Ritch et al studied 148 men who were residents of Kingston in Jamaica. The men had a mean age of 65 years and a mean serum prostate-specific antigen (PSA) level of 14.7 ng/ml. The men's serum levels of erythrocyte membrane LA, the ω3 PUFA docosapentanoic acid (DPA), and docoahexaenoic acid (DHA) were also measured.

The 54 men who had a PSA level of at least 2.6 ng/ml underwent biopsy. Of these, 24 had prostate cancer, 17 had a Gleason score of 7 or greater, and 11 had a tumor volume of 50% or greater.

The men's serum levels of LA correlated positively with Gleason score, DHA level, level of DPA plus eicosapentanoic acid, and tumor volume.

Ritch and co-workers were unable, however, to find a consistent correlation between PUFA levels and PSA levels.

They conclude that their findings support "previous studies indicating that the consumption of foods rich in ω6 PUFAs may promote the development and progression of prostate cancer."

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