Update on red and processed meat and colon cancers

The health and nutrition community has been sounding the alarm on red and processed meats and its well-established link to colorectal cancers for at least the last decade. Dedicated readers of our columns likely know that they should avoid processed meats as much as possible, choose nitrite- and nitrate-free processed meats if they must, and limit their intake of unprocessed red meats (yes, this includes pork) to no more than once every two weeks or so.

A team of researchers in the UK noted that the consumption of red and processed meats has indeed declined in the United Kingdom since the 1990's, when the most recent prospective studies looked at the links between red and processed meat intake and colorectal cancers (Int J Epidem 2019 doi:10.1093/ije/dyz064). Might this lower intake of red and processed meats - now averaging below the recommended maximum intake for those in the UK - have an effect on the risk of colorectal cancer?

The UK Biobank is a prospective study that began recruiting participants between 2006 and 2010. Nearly 500,000 men and women between the ages of 40 and 69 used a touchscreen application to report on their usual intake of general food groups, including red and processed meats, fish, fruit, vegetables, milk, cheese, alcohol, tea and coffee, and fiber intake. To validate these touchscreen surveys, a representative subset (over 175,000) of the participants filled out more detailed 24-hour recalls of everything they ate on at least one occasion over the course of the following year.

At the close of the data-gathering period, after an average of 5.7 years of followup (the longest followup being 8.6 years), the authors accessed the cancer and death registries of the appropriate countries and found over 2,600 cases of confirmed colorectal cancer. The authors compared the dietary intake of those who developed colorectal cancer with those who did not, taking into account age, education, smoking status, waist circumference, height, alcohol intake, level of physical activity and family history of colorectal cancer.

The UK government currently recommends that adults consume, on average, less than 90 grams per day of red or processed meats: that's about 3.2 ounces per day.

Compared to those who said they consumed only 21 grams of red or processed meat per day, on average (about .74 ounces per day or about 5.2 ounces per week), those who consumed just 76 grams per day of red or processed meat (that's 2.7 ounces per day or 19 ounces per week) were 20% more likely to develop colorectal cancer.

Unprocessed red meats increased the risk of colorectal cancer by 15% when comparing those who consumed less than 2 ounces of red meat per week with those who consumed a little over 13 ounces per week (that's about three servings).

Processed meats, such as bacon or sausage, increased the risk of colorectal cancer by 19% when comparing those who consumed a little over an ounce per week with those who consumed about 7 ounces per week.

What this means for you

It's clear that even if you're consuming less than the United Kingdom's recommended maximum intake or red or processed meats, you may still be at higher risk of colorectal cancer from that consumption. This does not mean that you should give up all red meat, however: if you like it, small amounts are still safe. Have processed meats like bacon or sausage as occasional (once a month or less) treats, and have a serving of lean red meat once every other week at most.

First posted: May 8, 2019