Friday Favorites: The Effects of Processed Meat on Lung Function

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Recently, the World Health Organization classified processed meat, also known as cured meat—bacon, ham, hot dogs, lunch meat, and sausage—as definitively cancer-causing in humans. As if that’s not enough, high processed meat consumption has also been associated with increased risk of dying prematurely from all causes put together, and is a risk factor for several major chronic diseases, such as type 2 diabetes, coronary heart disease, and stroke. But what about lung issues like asthma?

Nitrites are added to processed meats as preservatives to preserve their pink (so they don’t turn gray), keeping them less rancid-tasting, and to prevent the growth of diseases like botulism. But put that same sodium nitrite in the drinking water of lab animals, and they develop emphysema. They nearly all developed emphysema. But that’s all the scientific knowledge we had on the subject coming into 2007, until this study, which found that frequent cured meat consumption is associated with increased risk for developing diseases like emphysema in people, too––a form of chronic obstructive pulmonary disease (COPD). Eating it like every other day appeared to triple the odds of severe COPD. But it was just a snapshot-in-time study, so, we don’t know which came first––the sausage or the COPD. For that, we need prospective studies that follow people over time, and the big twin Harvard studies in both women and men both found that the risk of newly-diagnosed COPD increased with a greater consumption of cured meats.

Currently, we now have studies involving hundreds of thousands of people, showing that higher intakes of processed meat were associated with a 40 percent increased risk of COPD. It comes out to like an 8 percent higher risk of COPD for each hot dog you eat a week, or each weekly breakfast link sausage. What is going on?

Yes, there are advanced glycation end-products, so-called glycotoxins, that may be proinflammatory; there’s the saturated fat that can also trigger inflammation in the airways; the high salt content can present a potential risk for lung inflammation; or the increase in systemic inflammation in general. But the reason attention has focused on the nitrites is because nitrites may actually be one of the mechanisms by which tobacco smoke causes diseases like emphysema. Yes, cured meats are the principal source of dietary nitrites, but nitrites are also byproducts of tobacco smoke. One of the main constituents, besides the carbon monoxide and nicotine, are nitrogen oxides that are converted in the lung to nitrites.

The way nitrites appear to cause lung damage is by affecting connective tissue proteins like collagen and elastin. That’s what helps keep the airspaces in your lungs open, but nitrite can modify these proteins in a way that mimics age-related damage, including the fragmentation of elastin.

With that much lung injury, it’s logical to assume processed meat consumption could also exacerbate the disease of those who already have it. And indeed, cured meat consumption increases risk of COPD patients ending up back in the hospital, about twice the risk for those eating more than average, and it appears the more you eat, the worse it is.

Regarding lung health, processed meat intake has been associated with a likely increased risk of lung cancer, a decline in lung function, and chronic obstructive pulmonary diseases. But, what about asthma? High processed meat consumption has been associated with higher asthma symptoms as well.

We knew about higher maternal intake of meat before pregnancy, potentially increasing the risk of wheezing in her children later on (based on a study of more than a thousand mother-child pairs). And we’re not talking about aspirating meat into your lungs, and being misdiagnosed with asthma. Those who ate the most cured meats were 76 percent more likely to experience worsening asthma than those who ate the least. Since obesity is a likely risk factor for asthma, though, maybe the influence of the meat is just indirect, by contributing to weight gain? That might be a small part of it, but the main effect appears to be direct, suggesting a deleterious role of cured meat independent of weight. Put all the studies together, and processed meat intake appears to be an important target for the prevention of adult asthma in the first place.

Even if you don’t have any lung issues, processed meat consumption was negatively associated with measures of normal lung function, while fruit and vegetable consumption and dietary total antioxidant capacity was associated with better lung function.

But wait, you say. I just eat all natural, uncured hot dogs, with NO NITRATES OR NITRITES ADDED, in all caps. But if you magnifying glass the small print, it says “except those naturally occurring in… cultured celery juice.” See, to avoid saying they added nitrites, what they do is add something that has a lot of nitrates, like celery, and bacteria that convert the nitrates to nitrites. So, they are adding nitrites. They’re just straight-up duping consumers. We didn’t add any nitrites except, of course…for all the nitrites we added. We care about your health; so, no nitrites added. Who wants pepperoni with nitrites? So, we just added lots of nitrites. We would never add any nitrites. Now, just let the piggy picture distract you from the fact that we just lied to your face. Hormel was my favorite. “Except for those naturally occurring in seasoning”—pretty slick.

Europe doesn’t allow this kind of consumer fraud, demanding manufacturers explicitly label it as containing nitrites. You can’t even call it natural.

When Consumer Reports put it to the test, they found the nitrite levels in all the products were essentially the same; so “no nitrites” doesn’t mean no nitrites. Consumer Reports and the Center for Science in the Public Interest have petitioned to stop this misleading practice. Nitrites are nitrites. “Their chemical composition is absolutely the same, and so are the health effects.”

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