Red meat not as bad for you as we thought

The majority of evidence is quite strong that consuming too much red meat, especially grilled meats and processed meats, is linked to an increased risk of colorectal cancers (see our article on Nutrition and Colorectal Cancer). Note that this is the majority of evidence, however. As with so much research, the results obtained, and their quality, can depend on how the research is performed, how many people are recruited to participate, and even what the researchers choose to focus on. Much of the evidence relating to colorectal cancer comes from looking at adenomas (precancerous lesions) in the colon and rectum and associating their number, and sometimes their location and severity, with the patients' meat intake.

Today's article comes from Germany, where a team led by Prudence Carr of the German Cancer Research Cancer examined the colonoscopy results from nearly 16,000 men and women in the German state of Saarland, in southwest Germany (Am J Clin Nutr 2017;105:1453-61).

The participants filled out a 6-question food frequency questionnaire that asked them to estimate how often, on average over the previous year, they consumed red meat (defined as fresh pork, beef, or lamb), processed meats (such as sausages or lunch meat, regardless of whether they were made from red meat or poultry), or fresh poultry. The three additional questions addressed fruit, salads and vegetables, and whole grains. They further were surveyed regarding such habits as smoking, alcohol intake, and physical activity, and their height, weight, and any family history of colorectal cancer were also recorded.

Colonoscopies that were incomplete or showed poor bowel preparation were excluded from the analysis, as were those participants who had a history of Crohn disease or ulcerative colitis.

After taking into account age; gender; family history; smoking status; alcohol, fruit, and vegetable intake; and other factors affecting risk, the authors found that those who consumed red meat more than once a day had no clinically significant increase in number of adenomas or advanced adenomas when compared with those who consumed red meat less than once per week.

Somewhat surprisingly, the same was true for those who consumed processed meats multiple times per day when compared to those who consumed processed meats as much as once per week. Poultry was also not associated with the presence of adenomas.

That said, a closer look at where adenomas occurred showed that those who consumed processed meats most frequently were 87% more likely to have an advanced adenoma in the rectum than those who mostly avoided processed meats.

What this means for you

This is an impressively large-scale study and should be given fair weight in considering whether to consume red or processed meats. One drawback is that their food frequency questionnaire did not assess amounts - they asked how often the participants consumed red or processed meats, not how much they ate when they did so. Still, this study argues strongly for moderation: generally I tell my patients to avoid processed meats except as an occasional treat, and to consume red meat no more than once every two weeks. As we've said before: "Red meat is not bad for you; bologna is bad for you."

First posted: June 21, 2017