The meat industry has fallen on hard times. After a steady decline in meat consumption in past years, it took a couple of hard hits last month, with the breaking of the pink slime scandal, followed a week later by the publication of a Harvard study linking red meat to a higher mortality risk. If you’re feeling a little less hungry for a burger these days, it’s no wonder.

Pink slime aside, does red meat really deserve such a bad name? Or is it what’s added to red meat that’s to blame? The Harvard study was not the first to suggest that red meat is bad for us, but it was the first to differentiate unprocessed and processed red meat and identify a relatively greater risk involved when eating a processed product than, say, pure, unadulterated steak. What makes processed meat worse? The study authors surmise it’s the additives and preservatives.

You probably noticed the headlines that followed the Harvard study’s publication: “All Red Meat is Risky, a Study finds” and “Eating All Red Meat Increases Death and More Reasons to Never Eat Meat.” And yes, the authors who evaluated the health and diet of over 120,000 health professionals between 1980 and 2006 did find that study participants who ate a daily serving of unprocessed red meat (a three-ounce serving of beef, pork, or lamb as a main dish, mixed dish, or in a sandwich) had a 13 percent greater chance of death during the study.

Part of the issue is quantity. A daily serving of red meat, seven days a week, 365 days a year — not surprising to anyone — is going to be risky. The authors also note that the participants who ate the most red meat were less likely to eat healthier alternatives, such as fish, poultry, and whole grains, which are all foods associated with a reduced risk of death.

“We know that variety is the spice of life,” said Joan Salge Blake, a registered dietitian and spokesperson for the Academy of Nutrition and Dietics, who was not involved in the study. “A high intake of red meat is going to displace more nutritious foods in the diet that are correlated to reducing disease.”

The source of the meat may be an issue, as the study did not differentiate between grass-fed and free-range meat from industrially produced meat. “This is still an open question,” study co-author and professor of medicine at Harvard, Frank Hu, said in an email. “It is possible that grass-fed and grain-fed beef have different health and environmental effects, but there is no data at this point whether the grass-fed vs. grain-fed beef would have different effects on long-term chronic diseases and mortality. Certainly, more studies are needed to look at this issue.”

On her blog Summer Tomato, scientist and health writer Darya Pino points out that we can probably assume that the participants were eating industrially produced meat. She writes:

Given the time during which the study took place, it’s unlikely that any of the participants were eating non-industrial, grass-fed and pastured meat. I think this is an important point, particularly when considering cancer mortality, since toxic compounds tend to accumulate in the fat of animals.

Considering all this, a more apt headline may have been: “Eating Industrial Meat with No Moderation is Madness.” So it’s possible that lean, grass-fed beef, which has less saturated fat and more omega-3 fatty acids and antioxidant vitamins, may actually have a place (once in a while) in a “heart-healthy diet.”

This may be the type of red meat that An Pan, the study’s lead author and research fellow at the Harvard School of Public Health in Boston, is eating once or twice a week, a frequency he admitted to the Los Angeles Times. Though he did say that he’s forgoing bacon and other processed meats all together.

Based on the study results, it’s not hard to see why. In addition to finding that a daily serving of unprocessed red meat increased participants’ mortality risk by 13 percent, the authors found that those who ate a daily serving of processed red meat (i.e., two slices of bacon, one hot dog, a piece of sausage, salami, bologna, or other cold cut) had an increased risk of death of 20 percent. Furthermore, the study found that hot dogs and bacon are associated with a higher risk than other processed red meats.

So what does “processed” mean as it applies to meat? According to the Food and Agriculture Organization of the United Nations (FAO), meat becomes processed when it undergoes a processing technology (grinding and mixing, heat treatments, drying, etc.) as well as treatment (salting, curing with nitrites, etc.) for taste, texture, and preservation. There are all kinds of processed meats, and the FAO groups them into six broad categories according to processing technology. If you look closely at the categories, it’s apparent that some processed meats are more processed than others.

Sausage, which falls into the category of “fresh, processed meat products,” is less processed since it remains “fresh” or raw throughout processing. A hot dog undergoes more processing, as a “raw, cooked-meat product because it undergoes a heat treatment that gives it its “firm-elastic texture.”

Bacon receives more processing as a “cured cooked meat product.” Unlike sausage or hot dogs, bacon is an entire piece of muscle meat. It’s cured with a nitrite solution and then undergoes a heat treatment to reach “the desired palatability.” The most processed meats of all are products that fall into the “pre-cooked, cooked meat product” category, which undergo two heat treatments and include products such as blood sausage, liver pate, and corned beef in cans. (And don’t ask, because I have no idea where pink slime fits into all this.)

Why does processing make red meat worse for us? The study authors point to additives and preservatives as likely suspects for the “additional harm.”

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Suspect No. 1: Nitrites: added for flavor and to preserve meat’s pink color and extend shelf life. The authors cited studies linking blood nitrite levels to a disorder affecting the inner lining of the blood vessels and impaired insulin response. Nitrites can also convert to carcinogens, but the addition of ascorbic acid (vitamin C) or ethyorbic acid inhibit their formation. You can find uncured bacon in the grocery store, though these products still contain naturally derived nitrites. And since the carcinogens form during high-temperature cooking, it’s best to avoid charring your hot dogs or eating very well-done or burnt bacon.

Suspect No. 2: Salt (sodium): added to meats as a preservative and as a powerful flavor enhancer. High sodium intake is linked to high blood pressure, which increases the risk for heart disease and stroke. Two slices of bacon can contain as much as 460 milligrams of sodium, 19 percent of the recommended daily intake. A bun-length frank can contain up to 550 milligrams of sodium, amounting to nearly one-quarter of the recommendation. Add a bag of potato chips, and you can easily eat half the sodium you should eat in a day in a single sitting.

With suspects No. 1 and No. 2 operating side-by-side, it’s no wonder they’re exacting a high cost on health. The irony of this bad news about bacon is that sodium and nitrites are industry additives — the meat itself is innocent. (Well, not really: Bacon’s still got ne’er-do-wells saturated fat, cholesterol, and heme iron lurking around.) But what seems clear is that we’re making red meat worse for us by processing it.

So, if you must eat red meat, the latest science says, eat it unprocessed, and in moderation (once or twice a week at most). The healthiest red meat is most likely from the happiest animals — raised outside confined animal feeding operations, and on pasture. And in the mean time: Why not eat more plants?