What counts as processed meat? Why are the concerns about it? What's a safe amount? Registered dietitian Kathleen Zelman joins me to sort through a confusing topic.
Virtually all healthy eating guidelines—everything from the Dietary Guidelines for Americans to the recommendations put out by the World Health Organization, the American Cancer Society, and the American Heart Association—include some sort of recommendation to limit your intake of processed meat.
But there’s a lot of confusion about what counts as processed meat: Ham, bacon, pepperoni, and hot dogs are generally included in that category. But what about uncured bacon or hot dogs with no nitrites added? What about sliced turkey or roast beef from the deli counter? Are they processed?
And what exactly is it about processed meat that makes it a problem. Is it just about the nitrites? Is it sodium? Saturated fat? All of the above?
What about uncured bacon or hot dogs with no nitrites added? What about sliced turkey or roast beef from the deli counter? Are they processed?
I think there’s also some understandable confusion about what it means to “limit” your consumption. Is one serving a week too much? One serving a month? Is any amount safe?
Kathleen Zelman is a registered dietitian who, among other things, served as the director of nutrition for Web MD for many years. She recently wrote a white paper for the North American Meat Institute addressing some of these questions and concerns about processed meats. She sat down with me to discuss this further.
What counts as processed meat?
As Kathleen explains:
Minimally processed meat is the correct term for raw, uncooked meat products that have been minimally altered (grinding, cutting) to create familiar cuts like strip steaks or pork chops. No additives or preservatives are used. It is simply processed from the whole animal into edible portions you see in the grocery store.
Further processed is the term used for meat and poultry that has been transformed through salting, curing, fermentation, smoking, cooking, batter/breading and/or the addition of ingredients to enhance flavor or improve preservation and safety. Examples include hot dogs, ham, sausages, corned beef, lunch meat, bacon or beef jerky as well as canned meat and meat-based preparations.
You see the problem. Most of us would not call a piece of raw chicken or pork processed meat. But in the meat industry, these are considered processed meat. For that matter, most of us would not put a can of tuna in the same category as hotdogs or corned beef. And yet, in the meat industry, these are all “further processed” meats. The way processed meat is defined in research studies is also fuzzy and inconsistent, but tends to align more with the meat industry’s definition of “further processed.”
The way processed meat is defined in research studies is fuzzy and inconsistent.
But nomenclature aside, it’s important to note that processing serves some useful functions, such as inhibiting the growth of dangerous pathogens, increasing food safety, and extending shelf-life.
As Kathleen points out:
Our meat supply is safer than it has been in a long time because we have these additives serving the purpose of food safety, as well as the process of curing or fermenting or smoking.
RELATED: Can Processed Food Be Healthy?
What are the concerns with cured meats?
Most of the health concerns about processed meats come from large epidemiological diet studies that have linked the consumption of processed meats with increased risk of various diseases, including colon and other cancers of the digestive tract, heart disease, and diabetes.
Of course, correlation is not causation. And there could be a lot of other explanations for this finding. For example, people who eat a lot of processed meat tend to have less healthy lifestyles in general. They are more likely to smoke, for example, and less likely to exercise regularly. They tend to eat fewer fruits and vegetables, and so on. Some, but not all, processed meats are also quite high in sodium and saturated fat. So if you’re eating a lot of them, your diet is also going to be high in sodium and saturated fat, factors which may independently increase disease risk.
People who eat a lot of processed meat tend to have less healthy lifestyles in general.
Although attempts are made to control for all of these variables, it’s possible that high processed meat consumption is simply an indicator of a less healthy lifestyle and not a direct cause of disease.
On the other hand, the correlation between processed meat consumption and increased health risks has been pretty consistent across decades of research and hundreds of thousands of subjects. And there’s a pretty well-established mechanism of action that would explain the connection between cured and smoked meats and cancer.
The role of nitrites and nitrates
A lot of people think that the nitrites and nitrates in processed meats are the problem. Sodium nitrite and sodium nitrate are often added to cured meats like ham, bacon, and hot dogs. Uncured bacon and sausages are often made with celery extract, which is naturally high in nitrites. Ironically, the level of nitrites and nitrates in uncured products is often just as high as in their cured counterparts.
These compounds are added in order to preserve the meats and give them their characteristic flavors and textures. But nitrites and nitrates also have a variety of beneficial actions in the body. In fact, the primary source of nitrites and nitrates in the diet is vegetables. And many of the beneficial effects of vegetables may be thanks to their nitrite content.
The level of nitrites and nitrates in uncured products is often just as high as in their cured counterparts.
So, it’s not the nitrates and nitrites per se that pose a risk. The problem is that they react with other compounds—both in foods and in the body. These chemical reactions can create new compounds called nitrosamines, which are known to be carcinogenic.
As Kathleen explains, however, the amount of nitrosamines in processed meats is much lower than it used to be:
It was back in the seventies when [nitrosamines] became a concern, because when further processed foods were cooked at high temperatures, they created nitrosamine compounds that are carcinogenic to animals. And so it cast a shadow over cured meats. So the government placed limits on the amount of nitrate that can be added to cured meats, and they require the addition of sodium erythorbate or sodium ascorbate (a form of vitamin C) because these compounds prevent the formation of nitrosamines.
This is a key point because a lot of dietary intake data we rely on today were collected back in the 70s and 80s. Our food supply has changed a lot in the last 50 years. For example, beef and pork have both gotten substantially leaner. Processed meats are much lower in nitrosamines. So, the associations between diet and health that are based on what we ate 40 or 50 years ago may not be as relevant today.
With diet, context is everything
Kathleen also mentioned that vitamin C can play a role. Adding sodium ascorbate (a form of vitamin C) to processed meats helps to inhibit nitrosamine formation. And adding more fruits and vegetables to your meals can help block the formation of nitrosamines in your gut when you consume processed meats.
As is so often the case, we can’t evaluate the positive or negative impact of foods in a vacuum. It always depends on how much you’re eating, what you’re eating them with, and what you might be eating instead if you weren’t eating that. For example, the association between high intakes of processed meat and increased cancer risk is not seen in those who also have a high intake of fruits and vegetables.
The association between high intakes of processed meat and increased cancer risk is not seen in those who also have a high intake of fruits and vegetables.
So, if you do occasionally enjoy cured or processed meats, be sure to pair them with some vegetables. Bacon, lettuce, and tomato is not just a classic sandwich, but a smart nutritional pairing.
The choice is yours, and you can choose to enjoy these foods if you like them. But, after doing this deep dive into the research, talking to researchers, looking at those epi studies, time and time again, it was the high intakes of the further processed meat that were associated with the concerns. And so in the context of a healthy diet, you keep things in moderation.
How much is too much?
But what does moderation actually mean? The guidelines leave us hanging there but the epidemiological studies (although subject to the caveats mentioned above) may offer some clues.
Those who eat one or two servings per week have virtually the same risk as those who eat none at all.
In those studies that find a link, it is generally the people in the highest category of processed meat consumption that have an increase in risk. And that is is usually one or more servings of processed meat per day. Those who eat one or two servings per week have virtually the same risk as those who eat none at all.
In other words, eating bacon every morning for breakfast, ham every day for lunch, and hot dogs or pepperoni every night for dinner is probably not a great idea. But enjoying a little bacon or on the weekend, corned beef on St. Patrick’s day, and ham on the holidays appears to present little risk.
I’ll let Kathleen Zelman have the last word:
The evidence suggests that with these foods—because of the sodium, fat, and preservatives—we need to limit them in our diet. As a dietician, I'd probably say once or twice a week would be moderation... And be sure to be eating your fruits and vegetables, whole grains, and other nutritious foods to have wide variety of phytochemicals and nutrients.