The chicken or the egg … or both?

A new report has suggested that, for men already diagnosed with prostate cancer, “consumption of eggs and poultry with skin may increase the risk” of cancer recurrence or progression.

Now we are immediately going to issue our normal word of caution, and point out that what this study has done is suggest a possible association between eating above average quantities of poultry products (largely chicken and eggs, we would assume) and prostate cancer progression in a relatively small group of patients (1,267 to be exact). An association of this type is not the same as a clear demonstration of cause and effect. For example, the men who ate relatively large quantities of poultry may have other factors in  common that were not captured in this study. More work will be needed before doctors start telling patients to limit their poultry product consumption to a drumstick and 3 eggs a week.

What exactly did Richman et al. demonstrate in this study?

They asked men in the Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE) database to participate in a prospective study. The men who participated must have been diagnosed and treated for prostate cancer and have had no recurrence or progression as of the time of their enrollment in 2004-05. They then followed these men for an average of 2 years while studying the men’s consumption of processed and unprocessed red meat, fish, poultry, and eggs. And here is what they found:

  • There were 127 cases of prostate cancer-specific death or metastases, elevation in the PSA level, or secondary treatment during 2,610 person-years.
  • Intakes of processed and unprocessed red meat, fish, total poultry, and skinless poultry were not associated with prostate cancer recurrence or progression overall.
  • When one compared the patients who ate the very smallest mounts of eggs and poultry with skin to the men who ate the very largest amounts
    • There was a 2-fold increase in risk for a prostate cancer progression event among the men who ate the very largest amounts of eggs (a hazard ratio of 2.02)
    • There was a very slightly higher increase in risk of a progression event among the men who ate the very largest amounts of poultry with skin (a hazard rati0 of 2.26)
  • Men with high prognostic risk and a high poultry intake had a 4-fold increased risk of recurrence or progression compared with men with low/intermediate prognostic risk and a low poultry intake.

Now one of the most interesting things here is that we have all thought for years that eating lots of red meat was a big potential risk for prostate cancer progression. However, there was no sign of this effect in this study. Nor was there any signal that eating large amounts of fish or skinless poultry was a problem. It was only large amounts poultry with the skin and eggs that gave a “danger signal.”

What do we make of this?

Well the first thing we would say is what we always say … a “heart healthy” diet is a prostate healthy diet, and a heart healthy diet would be one that avoided particularly large quantities of any one type of meat or dairy product. Is worth considering the possibility that there is something being fed to our mass-produced poultry that might be accumulating in the skin and their eggs and that had some form of stimulatory effect of prostate cancer progression. Sure, it is certainly worth considering this. Alternatively, the whole thing could be a chance result in a relatively small group of men that was not observed in  a repetition of this experiment (which is not in any way intended to belittle what the study reports).

What’s the bottom line? Probably just that a diet that is particularly heavy in any one type of protein isn’t a very good idea to begin with. Have some more fruit and vegetables … and take the skin off before you deep fry your next spread of chicken wings!

2 Responses

  1. Is the above information valid for a product like “Egg Beaters” which is almost totally egg whites?

  2. Egg white-based products can certainly be assumed to be more “heart healthy” than whole eggs if eaten in significant quantities.

    However, for those of us who have taste buds as well as hunger, egg white-based products can be a rather less than appetizing substitute for actual eggs. The simple answer is to use eggs in moderation (or egg whites if they taste fine to you). A “heart healthy” diet doesn’t mean you can’t have eggs (or poultry). It means that eating a six-egg omelet for breakfast several mornings a week is not the world’s best idea, and nor is a regular diet of fried chicken with the skin on!

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