Does Vegetarianism Reduce Colorectal Cancer Risk?
At least that’s the conclusion of one large-scale study, "Vegetarian Dietary Patterns and the Risk of Colorectal Cancers," published March 9, 2015 in JAMA Internal Medicine.
Behind the Scenes of the Study
From 2002 to 2007, researchers recruited 77,659 Americans who varied in age, sex, race, geographic location, and socioeconomic status. Their one commonality was belonging to Seventh-Day Adventist churches. Because Adventists are encouraged to maintain a vegetarian diet, the investigators could research a larger group of vegetarians than one might typically find in meat-mad America.
An extensive food questionnaire sorted participants into five eating groups: non-vegetarian (48%) and four vegetarian subsets (totaling 52%): vegan, lacto-ovo vegetarian, pescovegetarian, and semi-vegetarian.Vegetarians had a 21% reduced risk and pescovegetarians a 42% reduced risk of getting the disease.Seven or so years later, investigators looked at the participants' health:
- Nearly 500 women and men had colorectal cancer (380 colon, 110 rectal).
- The 40,367 vegetarians had a 21% percent reduced risk compared with the 37,292 non-vegetarians.
- The largest reduced risk was found within the 7,811 pescovegetarian sample—42% reduced risk compared with the non-vegetarians.
"Vegetarian diets are associated with an overall lower incidence of colorectal cancers," the study investigators say. "Pescovegetarians in particular have a much lower risk compared with nonvegetarians."
But… There's a Numbers Problem
Here’s the problem: Many media reports on this study have concluded that going veggie is a way to reduce your colorectal cancer risk.
The truth is considerably more refined.
To get there, we first need to look at the numbers.
A healthreviewnews.org analysis reports that 252 cases of colorectal cancer were identified in the 40,367 vegetarians and 238 cases in the 37,292 non-vegetarians. That translates into 62.4 cases per 10,000 vegetarians vs. 63.8 cases per 10,000 non-vegetarians.
In short, there were 1.4 fewer cases of colorectal cancer per 10,000 people in the vegetarian group.
One case out of 10,000 participants—that's not much improvement in risk after all. A vegetarian diet reduced colorectal cancer risk in one case out of 10,000 participants.Sure enough, woefully underreported by both the researchers and the media is the fact that only the pescovegetarian diet showed a statistically significant association in reduced risk of colorectal cancer.
In the 7,811 pescovegetarian sample, there were 35 cases of colorectal cancer, in other words a significant 44.8 fewer instances per 10,000 participants.
So, Will Going Pescovegetarian Protect Me?
V (veggies) + F (fish) does not = P (protection).
Truth is, no one knows for sure that eating veggies plus fish—which in this study meant eating fish once or more per month—is the reason for the 42% reduced risk in getting colorectal cancers. When you’re looking at human lifestyles, there could be any number of ancillary reasons why American consumers of vegetables + fish had a significantly lower cancer risk.
It’s going to take a while to reel in real answers.
Stay tuned to Honest Health News, where you’ll never catch fish tales.by