The headlines were certainly scary enough to turn readers into vegetarians:
Fortunately for meat eaters out there, the study that prompted this week's dire warnings wasn't quite as absolute as it was made to appear.
For starters, studies linking red meat consumption to cancer aren't new. But this study, published online Monday by the journal Cancer, zeroed in on a specific culprit—processed red meat—and a particular body part—the bladder.
The report concluded that eating a lot of bacon, hot dogs and lunch meat appears to increase the risk of bladder cancer by 30%. The finding was made by analyzing the diets and health records of approximately 300,000 people between the ages of 50 and 71 who were tracked for eight years by the National Cancer Institute, part of the National Institutes of Health.
The apparent link showed up when researchers compared the incidence of bladder cancer among the 20% of study participants who ate the most red meat (the equivalent of about four slices of salami per day, on average) to the incidence for the 20% who ate the least (about half a slice of salami per day). Digging a little further, they found that steaks and hamburgers weren't to blame—only the processed red meats that contain nitrates and nitrites (which are used to preserve and flavor foods).
But hold on a second. The study also compared bladder cancer rates among those who ate the most processed meats (including processed white meats like deli turkey) and those who ate the least. That comparison found no increased risk for bladder cancer, even though a lot of the processed meat must have been processed red meats—the very same ones that made the red meat category look so risky.
When asked about this discrepancy, lead author Amanda Cross of the NCI acknowledged that the link between bladder cancer and processed red meat consumption was weak. "If the association was strong, you would expect to see at least a suggestion of an association for processed meat overall," she wrote in an e-mail.
The study itself said the findings offer "limited evidence" that the nitrates and nitrites in processed meats can raise the risk of bladder cancer. (The National Cancer Institute estimates that 70,530 people will be diagnosed with bladder cancer this year and that the disease will kill 14,680.)
Just to be sure we weren't being cavalier with our bladders, we discussed the statistics with Marjie McCullough, a nutritional epidemiologist at the American Cancer Society.
Because bladder cancer is strongly correlated with smoking, McCullough said the study is to be commended for trying to find other risk factors for the disease.
"It's novel in providing hints to how meat might be a factor," she said. "But these weren't really strong associations." The evidence isn't strong enough to warrant switching from salami to turkey, she added.
Cross herself said the study may be giving processed red meat a bad rap it doesn't deserve.
"That is why the main take-home message is that additional studies are needed," she said.