Reference
Richman EL, Kenfield SA, Stampfer MJ, et al. Choline intake and risk of lethal prostate cancer: incidence and survival. Am J Clin Nutr. 2012 Oct;96(4):855-863.
Design
Intake of dietary choline, supplements containing choline, and betaine (a choline metabolite) was examined prospectively and compared with the risk of lethal prostate cancer.
Participants
Data from the 47,896 men in the Health Professionals Follow-Up Study were analyzed. The diets of the 4,282 men who were diagnosed with non-metastatic disease during the follow-up period were assessed with a validated questionnaire 6 times during 22 y of follow-up period.
Outcome Measures
The primary outcome measure was lethal prostate cancer. A total of 695 deaths from prostate cancer occurred during the 879,627 person-years of data collected.
Key Findings
Men in the highest quintile of choline intake had a 70% higher risk of dying from prostate cancer (HR: 1.70; 95% CI: 1.18, 2.45; P trend=0.005) than men in the lowest quintile.
Practice Implications
Cancer patients want to know and should be told what foods not to eat. Recommendations should vary by type of cancer. Erin Richman’s work over the last several years provides us with a greater understanding of several of the key chemicals that may incite prostate cancer to grow.
This study makes more sense if we first review Richman’s March 2010 study. That paper, published in the American Journal of Clinical Nutrition, had examined the effect meat, fish, poultry, and egg consumption had on the risk of prostate cancer progression. She surprised many of us by reporting that egg and poultry consumption significantly increased risk of cancer progression while meat did not have a significant impact. Less than half a dozen eggs consumed per week was associated with a doubled risk of progression. Eating chicken with skin on it also had a similar unwanted effect. At the time, Richman theorized that the high choline content of the eggs might be responsible.
This new study confirms her earlier suspicion: Eggs, probably because of their high choline content, do pose a problem.
In the current study, the top 5 foods contributing to choline in the diets of the participants were whole eggs, beef, skim milk, reduced-fat milk, and poultry without skin. Consumption of these particular foods is already associated with prostate cancer risk.1–3 Usually the link between meat and prostate cancer has been considered to be the result of carcinogens (in particular the heterocyclic amines) formed during cooking.
The top 5 foods contributing to choline in the diets of the participants were whole eggs, beef, skim milk, reduced-fat milk, and poultry without skin.
Figg reported in October 2012 that men who consume the most ground beef more than double their risk of aggressive prostate cancer. “Interestingly, the consumption of rare or less cooked meat was not associated with an increased risk of prostate cancer.”2 This suggests it isn’t just the choline content but also the heterocyclic amine production during cooking that's to blame.
This new study of Richman’s is the first time that the potential of milk and beef to increase prostate cancer risk has been attributed to their choline content alone.
While the link between choline and fatal prostate cancer is becoming clear, the risk-benefit analysis remains murky. Choline is an essential nutrient and is associated with a number of positive health effects, including possibly preventing fatty liver disease and cognitive decline in the elderly. We cannot and probably should not put all of our patients on choline-free diets.
This current paper, in light of Richman’s earlier study, solidly reinforces the theory that high dietary choline promotes prostate cancer, and we should take this into account when providing dietary guidance to men, particularly those with prostate cancer.
We should be aware that there are other dietary factors associated with prostate cancer besides high choline and heterocyclic amines. A study by Stott-Miller et al published in January 2013 reported significant associations between fried food consumption and prostate cancer. Eating French fries once a week or more increased risk of prostate cancer by 37%. Fried chicken once a week increased risk by 30%, doughnuts by 35%, and fried fish by 32%. Aggressive disease risks increased slightly more; for example, eating fried fish increased risk of aggressive disease by 41%.4 While these associations do not speak to risk of progression or fatality, they do further define the dietary advice we should provide to prostate cancer patients.
Patients rarely want to know all these details; instead they want a clear bottom line. We have to explain that this knowledge is still a work in progress.
For more research involving integrative oncology, click here.
