Prostate cancer is the second most common cancer in American men, just behind skin cancer. It is the second leading cause of cancer death for men behind only lung cancer. The American Cancer Society estimates that 238,590 new cases of prostate cancer will be diagnosed this year and about 29,720 men will die from the disease. Men have about a one-in-six shot of being diagnosed with prostate cancer during their lifetime. Luckily, most men diagnosed with prostate cancer do not die from it – two million men currently live with the disease in the United States alone. If you catch prostate cancer while it remains localized, the survival rate is pretty much 100%, but once the cancer begins to progress, the survival rate drops down to 32%.
Is there anything men can do to reduce their risk of developing the disease? More importantly, is there anything men who get diagnosed with prostate cancer can do to improve their chances of survival? It might be as simple as looking at what we’re eating as there’s a fair amount of evidence associating two popular foods with prostate cancer progression and growth.
Chicken and Prostate Cancer
A report in 2010 out of Harvard University, the Cancer of the Prostate Strategic Urologic Research Endeavor, showed men with prostate cancer who consumed a large amount of chicken quadrupled the chance of their disease progressing.1
What’s the explanation for this?
The scientists thought it might be the high levels of heterocyclic amines, carcinogens that build up when meat is cooked at a high temperature, which are present more in poultry than in other meats. Another explanation could come from the fact the researchers noticed the cancer developed far more quickly in those men who ate chicken with skin on as opposed to those who ate their chicken without skin. So according to this study, men with prostate cancer could eat skinless chicken breast (if they were to eat chicken) and not increase the risk of progression. Granted, this is only one study and there will need to be a lot more follow-up work to determine how significant these findings were, but it’s still cause for some concern.
Eggs and Prostate Cancer
The same Harvard study observed that men with prostate cancer who averaged just under an egg per day had a two-fold increased risk of prostate cancer progression compared to men who didn’t eat eggs. What’s more, these findings were supported by a follow-up study in 2011, which determined that even healthy men may be at an increased risk of developing a lethal form of prostate cancer by eating over 2.5 eggs per week compared with men who don’t eat eggs.2
What could possibly be the explanation for this?
Some researchers and doctors think it may be the high levels of choline present in eggs. A study in 2012, also out of Harvard University, determined that among a group of 47,896 men, those with the highest levels of choline intake had a 70% increased risk for getting lethal prostate cancer.3 But choline is good for you, right? Absolutely, and we do need to include choline as part of our diets. But what these researchers found is that it’s not the choline intake necessarily, but the trimethylamine oxide (TMAO) that choline is converted to (first to trymethylamine by gut bacteria and then to TMAO in our liver) that could increase inflammation and promote cancer progression along with cardiovascular risk.4
Gut bacteria also produce this same toxic chemical when they metabolize L-carnitine in red meat as discovered in a landmark study from the Cleveland Clinic published this past May.5 What’s most interesting about their findings is they discovered that in contrast to the omnivorous human subjects studied, those consuming a plant-based diet produced a negligible amount of TMAO even when consuming L-carnitine. So what does this mean and what are the possible implications with regards to choline intake? Since the intestinal microbiota of those consuming a predominantly plant-based diet are different from omnivores, and since plant-based eaters don’t convert L-carnitine into TMAO as much as omnivores, could the same thing be true for choline? It’s possible, but again, we’re going to need to see more studies to confirm this theory. It’s worth noting that there are plenty of excellent plant-based sources of choline, including broccoli, cauliflower, collard greens, and other cruciferous vegetables.
So, Do We Eat Poultry or Not?
While these studies aren’t entirely conclusive and will require extensive follow up, which is likely to happen, they are certainly cause for concern. We could always choose to ignore them, but if we decide to be prudent we may want to reduce our consumption of eggs and chicken skin, at the very least, or avoid them altogether. We can also include foods in our diet that have been shown to be protective against prostate cancer growth, including flax seeds6,7, cruciferous vegetables8, other plant foods high in lignans and isoflavones, and maybe even soybeans (non-GMO of course).9 Additionally, we now know that exercise can greatly increase your chances of survival as well. So men, if you’re going to keep eating chicken and eggs, stay active, eat lots of nutrient-dense plants and seeds, avoid chicken skin, and hope these studies on poultry turn out to be false.
References:
1. Richman EL, Stampfer MJ, Paciorek A, Broering JM, Carroll PR, Chan JM. 2010. “Intakes of meat, fish, poultry, and eggs and risk of prostate cancer progression.” The American Journal of Clinical Nutrition. March.
2. Richman EL, Kenfield SA, Stampfer MJ, Giovannucci EL, Chan JM. 2011. “Egg, red meat, and poultry intake and risk of lethal prostate cancer in the prostate-specific antigen-era: incidence and survival.” Cancer Prevention Research. December.
3. Richman EL, Kenfield SA, Stampfer MJ, Giovannucci EL, Zeisel SH, Willett WC, Chan JM. 2012. “Choline intake and risk of lethal prostate cancer: incidence and survival.” The American Journal of Clinical Nutrition. October.
4. Tang WH, Wang Z, Levison BS, Koeth RA, Britt EB, Fu X, Wu Y, Hazen SL. 2013. “Intestinal microbial metabolism of phosphatidylcholine and cardiovastcular risk.” The New England Journal of Medicine. April.
5. Koeth RA, Wang Z, Levison BS, Buffa JA, Org E, Sheehy BT, Britt EB, Fu X, Wu Y, Li L, Smith JD, DiDonato JA, Chen J, Li H, Wu GD, Lewis JD, Warrier M, Brown JM, Krauss RM, Tang WH, Bushman FD, Lusis AJ, Hazen SL. 2013. “Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis.” Nature Medicine. May.
6. Demark-Wahnefried W, Robertston CN, Walther PJ, Polascik TJ, Paulson DF, Vollmer RT. 2004. “Pilot study to explore effects of low-fat, flaxseed-supplemented diet on proliferation of benign prostatic epithelium and prostate-specific antigen.” Urology. May.
7. Demark-Wahnefried W, Price DT, Polascik TJ, Robertson CN, Anderson EE, Paulson DF, Walther PJ, Gannon M, Vollmer RT. 2001. “Pilot study of dietary fat restriction and flaxseed supplementation in men with prostate cancer before surgery: exploring the effects on hormonal levels, prostate-specific antigen, and histopathologic features.” Urology. July.
8. Hayes JD, Kelleher MO, Eggleston IM. 2008. “The cancer chemopreventive actions of phytochemicals derived from glucosinolates.” European Journal of Nutrition. May.
9. Morton MS, Chan PS, Cheng C, Blacklock N, Matos-Ferreira A, Abranches-Monteiro L, Correia R, Lloyd S, Griffiths K. 1997. “Lignans and isoflavonoids in plasma and prostatic fluid in men: samples from Portugal, Hong Kong, and the United Kingdom.” The Prostate. July.
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