On the other hand, a doubling of the risk of prostate cancer recurrence or progression was observed in men who ate poultry with the skin still on or an average of five and a half eggs a day, according to a study with 1,294 men published in the American Journal of Clinical Nutrition.
The researchers, led by Erin Richman, were careful to recommend caution interpreting the results. “Our analyses of poultry and eggs were exploratory, because no studies have examined the post-diagnostic intake of these items and risk of prostate cancer progression,” they stated.
The researchers noted that the saturated fat content of meat was not linked to prostate health, and that the heterocyclic amines may be responsible for the observations. Heterocyclic amines are mutagenic compounds reportedly found at much higher concentrations in well-cooked poultry than in other meats.
Meat consumption and cancer risk remains a hot topic for many consumers, with obvious implications for the food industry. A study from the US National Cancer Institute reported that high intakes of red and processed meats may raise the risk of lung and colorectal cancer by up to 20 per cent.
The World Cancer Research Fund published a report in 2007 that directly linked diet to cancer, with alcohol and red and processed meats posing particular risks.
The link between eggs and prostate cancer may be due to the high levels of dietary choline, wrote the researchers. “Egg consumption is a determinant of plasma choline, and higher plasma choline was recently reported to be associated with a greater risk of prostate cancer,” said the researchers.
Commenting independently on the new study, Nell Barrie, science information officer at British charity Cancer Research UK told FoodNavigator: “Importantly, this study doesn't show that eating more poultry with skin or eggs increases the risk of getting prostate cancer - it only looked at men who already had the disease.
“There is no firm evidence that eating poultry with skin or eggs increases the risk of prostate cancer progressing in people who already have the disease. This question can only be answered with further research, and it's difficult to tease out the effects of individual types of food on cancer,” added Barrie.
Richman and her co-workers recruited almost 1,300 men with prostate cancer without recurrence or progression already participating in the Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE). Dietary intakes of meat and eggs were determined using a 127-item food frequency questionnaire.
During two years of follow-up 127 prostate events were documented. However, no link between the intakes of processed and unprocessed red meat, fish, total poultry, and skinless poultry was observed by the researchers.
An increased consumption of eggs and poultry with skin was associated with a two-fold increase in the risk of prostate cancer recurrence or progression, said the researchers.
“Overall, our results support the hypothesis that diet may influence the progression of prostate cancer among men with localized disease,” wrote the researchers. “In particular, consumption of poultry with skin and eggs may be associated with an increased risk of prostate cancer progression.”
“We acknowledge that our study had several limitations, including a short follow-up, a small number of prostate cancer deaths or metastases, and a lack of prediagnostic dietary data,” added the researchers. “The Diet and Lifestyle substudy of CaPSURE has yet to accrue many events of prostate cancer metastases or death.”
Source: American Journal of Clinical Nutrition
Published online ahead of print, doi:10.3945/ajcn.2009.28474
“Intakes of meat, fish, poultry, and eggs and risk of prostate cancer progression”
Authors: E.L. Richman, M.J. Stampfer, A. Paciorek, J.M. Broering, P.R. Carroll, J.M. Chan