This transcript has been edited for clarity.
Francisco Lopez-Jimenez, MD, MBA: Hello, and welcome back to the Mayo Clinic–Medscape video series. I am Francisco Lopez-Jimenez, cardiologist and professor of medicine at Mayo Clinic. Today we will be discussing whether eating red meat is harmful. I am joined by my colleague, Dr Steve Kopecky, consultant and professor of medicine, and an expert in this area. Welcome, Dr Kopecky.
Stephen L. Kopecky, MD: Thank you, Francisco.
Lopez-Jimenez: The United States has some of the highest red meat consumption per capita in any country of the world. A controversial 2019 Annals of Internal Medicine guideline encouraged red meat consumption, concluding that we do not need to cut down. Could you briefly tell us the key points of the study that supported this conclusion?
Kopecky: This was a systematic analysis of systematic analyses, so the authors analyzed multiple studies and concluded that we do not need to cut down on the amount of red meat we eat. The study showed that eating red meat does increase cardiovascular events and cardiovascular death, but the overarching conclusion was that the increase was not big and people like to eat red meat, so we really should not change our red meat–eating habits.
Processed Meat vs Unprocessed
Lopez-Jimenez: Do you believe that all red meat is the same in terms of health effects?
Kopecky: That is an important question. Red meat can be divided into two categories: unprocessed and processed. Unprocessed meat is the whole organ, the whole muscle, with no additives. Processing adds a lot of other ingredients.
What is a processed meat? If it is cured, smoked, or fermented, if it has salt added and/or chemical preservatives, it is a processed meat. The top five processed meats eaten in this country are lunch meat, sausage, hot dogs, ham, and bacon. Every 50 grams (about 2 oz) of processed meat you eat daily increases your risk for coronary heart disease by about 40% over a few years. About two thirds of that risk seems to be related to the sodium added to the processed meat as a preservative.
Unprocessed red meat is not as bad by any means in terms of causing coronary heart disease. But it does not really mean that we can eat it ad lib. People think, well, they said it's okay, so I will have a big 18-oz steak, but our intake of red meat really should be considerably less than we eat daily.
Lopez-Jimenez: Results in this paper were all over the place. There was not a unified result in all of these studies. Why is it so difficult to conduct a study on red meat intake and effects on health?
Kopecky: Our standard in medicine is a randomized, placebo-controlled, double-blind trial. You cannot double-blind red meat. And you cannot conduct a randomized trial; true randomization of a general population sample would include vegans and vegetarians, and that would be a whole different subset. Even the Mediterranean diet trial, the PREDIMED study, had difficulties with randomization. We just cannot do a standardized trial. There is a lot of crossover; a lot of people who are eating red meat "a little bit" will eat a little bit more. They will have a family reunion or 4th of July picnic or something.
The studies use a recall questionnaire every couple of years and ask "How much red meat do you eat every day?" As humans, we tend to forget or misremember what we eat. It is also difficult to know the dose of the red meat that people take in. Plus, what accompanies the red meat? If you are eating red meat with a lot of fat on it, mayonnaise, and processed foods, etc., this confounds the analysis quite a bit. It is almost impossible to separate those things out.
No Meat Not Necessarily Healthy?
Lopez-Jimenez: Another question is what the non–meat eaters are eating, right? That may not be healthy either; if they eat a lot of sugar or other kinds of fats, these factors may also be affecting the outcomes.
Red meat has a considerable amount of saturated fat. This has been linked to CAD since the Seven Countries study published nearly 40 years ago. What have we learned that is still true regarding saturated fat?
Kopecky: The saturated fat story from the Seven Countries study is interesting. If you go back and look at the notes from their investigator meetings, many investigators from the Mediterranean countries that were involved said to the principal investigator, you are focusing a lot on red meat and saturated fat. But here, we use more monounsaturated fat, such as olive oil, for our primary source of dietary fat. The principal investigator, Ancel Keys, was a leader in this field, and many of the things he espoused are correct. But he insisted that it was more red meat and that is where the saturated fat came from.
Subsequent studies have been conducted that seem to contradict this idea. One of our colleagues, Dr Bob Frantz, was among a group that published data showing that saturated fat was not that important. Instead, they said to try to consume more olive oil in the diet and limit saturated fat to a certain degree.
The other consideration is what you eat instead of saturated fat. When those studies were done, people tended to eat a lot of carbohydrates and trans-fats — which have now been outlawed — and a lot of carbohydrates that contained trans-fats were highly processed. Again, it is difficult to separate out individual macronutrients in a diet. The best way to handle this is to help us and our patients understand what specific foods are good to eat, such as lean red meat, or blueberries, or an apple — suggestions like that.
Lopez-Jimenez: Going back to red meat consumption, the analysis of the study published in the Annals showed a modest but significant increase in cardiovascular risk but only in the group that had a very high intake of red meat. Will it be safe to say that eating modest amounts of meat will not necessarily be harmful when compared with a vegetarian diet? Any thoughts on that?
Kopecky: That is a good point, Francisco. If you look at what we have eaten for the past tens of thousands of years, we have eaten red meat, but we did not eat a lot of it every day. We did not go out and kill a deer for breakfast. We would use meat for celebratory purposes: a wedding, a new king or queen, or a birth — a celebration of some sort. We have been eating small amounts of red meat forever. Emphasis on small amounts.
If you look at some of the remote tribes in the world, such as those in the Bolivian jungle, the Amazonian jungle, or the Tsimane Indians who have some of the healthiest hearts in the world, they eat a few ounces of red meat daily, on average. The PREDIMED Mediterranean diet study allowed up to 3 oz of red meat a day. When I ask my patients to eat 3 oz of red meat and I show them that it is the size of a deck of cards, they say, "Oh my God, that is like two bites, Doctor. What am I going to do?" We have to encourage our patients to slowly change their habits. I emphasize the slow, one-bite-at-a-time approach, because you cannot change this quickly. Take one bite and fill it in with something else that may be a little healthier for you.
The bottom line is that processed meats are the ones to avoid. It is okay to have small amounts of unprocessed meat, but be careful because the amount can get away from us quickly. Finally, whole red meat, while it does not seem to increase our health risks much (although it does increase the risk for diabetes), does not seem to lower our risk at all as do some of the other foods we eat, such as fruits, vegetables, legumes, and olive oil.
Lopez-Jimenez: The Mediterranean diet has been shown to be beneficial for cardiovascular disease event reduction. Does this dietary pattern allow red meat, and if so, how much?
Kopecky: PREDIMED suggested only 3 oz of meat a day. You don't have to eat meat on a Mediterranean diet, but if you do, the limit is 3 oz a day, and avoid processed meats as we spoke about earlier. Processed meats are the ones that are full of sodium, raise blood pressure, and contain a lot of chemical additives, and that is what we must be careful with. The issue, of course, is that when we are in times like now with the pandemic, we tend to eat a lot more premade foods, including processed meats and luncheon meats.
Lopez-Jimenez: Thank you, Dr Kopecky. Those are important points. Thank you for joining us on theheart.org | Medscape Cardiology.
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Cite this: Is Red Meat Bad for Your Heart? - Medscape - Feb 24, 2021.