The journal Cancer Prevention Research recently published a study online ahead of print examining the link between dietary factors and risk of fatal prostate cancer. Among other things, the researchers concluded that consumption of eggs may increase the risk of fatal prostate cancer. Given the large body of research supporting the health and nutritional benefits of egg consumption, this finding is unexpected. However, statistical associations do not prove cause and effect. Rather, they show relationships and are best used in guiding the direction of future research. In this study, it is important to note that researchers only looked at a specific population – predominantly Caucasian, adult men – and that there were few cases of lethal prostate cancer overall. This finding in and of itself calls into question the rather bold claims made in the press regarding the study results.
Additionally, certain dietary factors were not taken into account, such as foods commonly eaten with eggs like bacon, sausage, fried potatoes, cheese and various refined carbohydrates. According to the recently released 2010 Dietary Guidelines, eating an egg a day is safe and healthy for most individuals. Nevertheless, it is important to pair eggs with other good-for-you foods, such as fruits, vegetables, low-fat dairy and whole grains as part of a balanced diet.
If you are interested in further information about the study, here are some of the specifics:
• Study participants included 27,607 male health professionals from the Health Professional Follow-up Study (HPFS) followed from 1994 to 2008. Typical dietary intake was measured using a semi-quantitative food frequency questionnaire to determine how often each participant consumed red meat (processed and unprocessed), poultry and eggs (with yolk).
• The outcome studied was fatal prostate cancer, which included death from prostate cancer or organ metastases.
• A total of 199 events of lethal prostate cancer were observed among the 27,607 men over the follow-up period. In other words, only 0.7% of subjects developed lethal prostate cancer.
• The researchers concluded that men who consumed 2.5 or more eggs per week had an 81% increased risk of lethal prostate cancer compared to men who consumed less than half an egg per week.
• The study did not find a significant association between egg intake and progression of prostate cancer after diagnosis.
• Researchers adjusted for age, body mass index (BMI), smoking and physical activity. No adjustments for other dietary factors were made.