Harvard Heart Letter

Red meat: Avoid the processed stuff

Beef, pork and other red meats are okay for the heart, but not hot dogs, cold cuts, and other processed meat.

Many people who try to follow a healthful diet eat red meat with a side order of guilt. A study suggests that eating beef, lamb, pork, and other red meat is okay for your heart and arteries as long as it hasn't been smoked, cured, salted, or otherwise preserved. But go easy on processed meats like bacon, cold cuts, and hot dogs.

Dietitian Renata Micha and colleagues from the Harvard School of Public Health gathered information from 20 completed or ongoing studies of diet and health. It gave them detailed data on diet, including meat consumption, from 1.2 million initially healthy participants, 27,000 of whom went on to develop heart disease, diabetes, or stroke.

Key points

  • Red meat may not be as bad for your heart as earlier research has suggested.

  • A large Harvard-based study showed that people who ate a serving of unprocessed red meat (beef, lamb, pork, hamburger) a day had no more heart disease than those who rarely ate meat.

  • Eating processed meat, like bacon and hot dogs, did boost the risk of developing heart disease and diabetes.

Rates of these three diseases were no higher in the group of participants who ate red meat eight times a week than they were among those eating red meat once a week or less. The story for processed meat was completely different: every serving per day of processed meat increased the risk of developing heart disease by 42% and the risk of diabetes by 19%. The researchers presented their results at an American Heart Association conference in San Francisco in March 2010, and published them in the June 1, 2010, issue of Circulation.

Nutrient-wise, unprocessed and processed red meat are fairly similar. Processed meat has slightly more fat and calories and less protein and cholesterol per serving than unprocessed meat. The biggest nutritional differences between unprocessed and processed red meat are salt (four times more salt in processed meat) and nonsalt preservatives (higher in processed meat). The researchers suggest that excess salt and preservatives may partly explain the difference in cardiovascular effects.

Evolution of science

Pundits, comics, and nutrition-research skeptics pounced on the conclusion that red meat may be okay for the heart, calling it a flip-flop or worse. Some likened the work to a scene in Woody Allen's 1973 movie, Sleeper, in which scientists of the future shake their heads that steak, cigarettes, and hot fudge were once "thought to be unhealthy ... precisely the opposite of what we now know to be true."

That view certainly gets laughs or stirs moral outrage. But it overlooks the evolutionary nature of scientific and medical research, as well as researchers growing ability to tease apart elements of the diet that were once lumped together.

Take dietary fat as an example. Beginning in the 1960s, when fat was identified as dietary enemy No. 1, we have been urged to avoid it. Since then, research has revealed that different fats have different effects on heart disease, from bad (trans fats), to neutral (saturated fat), to good (unsaturated fats). Our knowledge of carbohydrates is undergoing a similar evolution.

Instead of viewing the new findings as a flip-flop, take them as good news for carnivores. "Meat will be in our diet for a long time. It's important to start taking a look at which ones are the healthiest, and which aren't," says study co-author Dr. Dariush Mozaffarian, an assistant professor of medicine at Harvard-affiliated Brigham and Women's Hospital.

Take-home lessons

The researchers didn't find that eating red meat is good for you, just that consuming it doesn't seem to affect the risk of developing heart disease or diabetes. Other research has suggested that frequently eating red meat increases the chances of developing colon and other cancers, something the Harvard researchers didn't examine.

Keep in mind that this analysis won't be the last word on the subject. It is limited by the quality of the data in the 20 original studies, and will almost certainly spur other researchers to examine the effect of meat consumption on cardiovascular disease.

This work doesn't mean you should indulge your carnivorous appetite. The best sources of protein are still fish, beans, nuts, and poultry. But the findings do suggest that eating red meat a few times a week can be part of a healthful diet, and you don't need to feel guilty when you cook a steak or order a lamb chop.

The finding that routinely eating processed meat boosts the chances of developing heart disease and diabetes is worth paying attention to. One serving of processed meat a week — bacon with your Sunday morning eggs or pepperoni pizza on Saturday night — falls in the "in moderation" category. More than that, though, and you could be doing your heart a disservice.