Nutritional Pearls: Red Meat Does Not Lead to Heart Disease
Ron is a 46-year-old overweight man who is worried about his risk of heart disease. In an attempt to lower his risk, Ron recently adopted a vegetarian diet, but at his most recent check-up, tells you that he is struggling to give up meat altogether.
How do you advise your patient?
(Answer and discussion on next page)
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Answer: Occasionally consuming unprocessed, lean red meat will have little effect by itself on their risk factors for heart disease, in the context of an otherwise healthy diet.
A Mediterranean-style Diet is by no means a vegetarian diet. It includes as one of its 9 principles the idea of less red meat and leaner meats overall: an average of about 4 ounces of meat per day (including both land and sea animals), and not consuming more than about 1 serving of red meat (which includes beef, pork, lamb, goat, and game animals such as venison) per week.
For some people this seems too permissive, arguing that the research shows that a strict vegan diet of no animal protein whatsoever confers even more health benefits than a Mediterranean-style diet. They feel that physicians should advocate that their patients adopt a vegan diet because it is the "best" diet.
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I won't be arguing that particular case today. Instead, today's article looks at the association between unprocessed red meat intake and the markers of cardiovascular disease in the context of randomized controlled trials, the gold standard of clinical research.
The authors of this study, all at Purdue University, scoured the literature and identified 24 randomized controlled trials that compared groups that consumed an average of at least 0.5 serving of unprocessed red meat per week (with one serving defined as 2.5 ounces of cooked meat) with a control group of those that consumed less than 0.5 serving of unprocessed red meat per week. The studies qualified for inclusion in their review if they also included only adults 19 years of age or over and reported on at least one of the following risk factors for cardiovascular disease: total cholesterol, LDL cholesterol, HDL cholesterol, the ratio of total to HDL cholesterol, triglycerides, and blood pressures. The 24 trials included nearly 1100 adult men and women and lasted from 2 to 32 weeks.
The authors' working hypothesis was that consuming at least 0.5 servings per day, on average, of unprocessed red meat would increase people's risk of heart disease by negatively affecting at least one of the relevant risk factors, but to their surprise they found that "the results showed no differences in postintervention values" between the groups who consumed at least 0.5 serving of red meat per day or less than 0.5 serving of unprocessed red meat per day. Further, "there was no indication that consumption of progressively higher red meat amounts influenced these... risk factors."
They checked their work quite carefully by performing various analyses that might have shown one or more of the individual studies, or certain smaller or larger levels of red meat intake, having too much influence over the whole, but found nothing.
In conclusion, the researchers note that both the DASH diet (Dietary Approaches to Stop Hypertension) and the Mediterranean Diet both include modest amounts of unprocessed red meats and both are considered "heart healthy" diets, although the research into the Mediterranean Diet's effectiveness has largely been limited to observational studies (with one significant randomized controlled trial). Further, much of the research into red meat either groups all red meats, both processed and unprocessed together, or doesn't adequately specify what type of meat or red meat is being researched or recommended.
What's the "Take-Home"?
If your patients would like to adopt a vegan diet, by all means: let them do so. For the vast majority of my patients (and most people I talk to), a vegan diet is simply unsustainable for the long term. If your patients don't want to give up red meat, it seems clear that having a leaner steak once a week or so, if they're following an otherwise healthy diet, will have little effect by itself on their risk factors for heart disease.
Bear in mind that this study focuses on unprocessed red meat and not processed meats like sausage, cold cuts, bacon, or meats that have been smoked, cured, salted, or otherwise chemically preserved.
O’Connor LE, Kim JE, Campbell WW. Total red meat intake of ≥0.5 servings/d does not negatively influence cardiovascular disease risk factors: a systemically searched meta-analysis of randomized controlled trials. Am J Clin Nutr. 2017;105:57-69.