Dutifully observing the national obsession with the phrase “according to the latest study,” Reuters distributed a news story yesterday with a blaring headline: “Chemicals in meat may be linked to bladder cancer.” True? False? A closer look at the actual study, published in the journal Cancer, reveals another case of fear-based journalistic hype. Let’s see what the researchers themselves have to say:
Although we saw no association with intake of processed meat, there was evidence of an elevated risk of bladder cancer with nitrate plus nitrite from processed meats. In addition, by estimating total dietary exposure to nitrate and nitrite from values in the literature, we observed a statistically significant increased risk with dietary nitrite.
In other words, the authors didn’t actually find much of a hypothetical “link” between processed meat and bladder cancer (or chicken, turkey, steak, beef, bacon, hamburger, and sausage, for that matter). They were, however, able to monkey around with their data—separating it out into different categories of processed meats—until something came out. But even this wasn’t terribly conclusive.
Is there an increased risk from dietary nitrite and nitrate? Some nitrate is converted to nitrite in the body, both chemicals occur naturally, and they’re found in many foods other than processed meat. Ninety-one percent of the nitrate we consume comes from vegetables and drinking water. Just six percent comes from meats.
And that old saw about nitrates, nitrites, and “cured” meats? It may be a bunch of baloney too. Cook’s Illustrated recently published the results of lab tests that found “uncured bacon actually had higher levels of nitrite than the cured meat.”
The Cancer article authors conclude:
This study provides limited evidence for a role of total dietary nitrite and nitrate plus nitrite from processed meat in bladder carcinogenesis…. Additional research is needed to confirm our findings of a possible increased risk of bladder cancer with intake of red meat and especially for PhIP, as prospective investigations of meat-related mutagens and this malignancy are lacking. (emphasis added)
Of course, reading the fine print often kills the news angle. Nobody wants to write a story saying that “evidence linking processed meat to bladder cancer is really limited, and scientists want to do more research.” Talk about a snoozer.
And as usual, every study has an equal and opposite study. There’s research showing that nitrite- and nitrate-rich foods may help people survive a heart attack. Another study found no association between nitrite and cancer in rats.
Here’s the bottom line: Your hot dog and deli-meat sandwich are just fine.