Does Red Meat Cause Heart Disease?

How often do you consume red meat?  Have you ever wondered whether red meat intake will have an impact on your heart health?  I wanted to share this article with you since this is such an important topic in nutritional science.  Since heart disease is the #1 cause of death worldwide, I’m always interested in any dietary or lifestyle factors that impact our cardiovascular risk.  This is also an important topic since many populations consume red meat and its intake is increasing around the world (13).  For those who consume red meat, the average daily intake is 50-100 grams (13).  In Canada, lean meats (including red meat) are considered a healthy protein option, but it’s recommended to limit your intake of processed meats (15).

This issue has only become more confusing over time since one “negative” red meat study is inevitably followed by a “positive” red meat study.  It’s important to mention some key points regarding nutritional research about red meat.  First, almost all of the research done on red meat is “observational”, meaning the researchers follow groups of people (with different meat intakes) and observe if there are any differences in rates of heart disease, etc. over time.  It’s very difficult to show a “cause-and-effect” relationship with observational studies because many other variables can contribute to heart disease risk over the course of the study (i.e. smoking, BMI, activity level, alcohol intake, dietary quality, and more).  Second, it’s very important that we delineate between “processed red meat” and “unprocessed red meat”.
Unprocessed red meat = beef, pork, veal, horse, sheep.
Processed red meat = sausage, salami, bacon, ham.
Typically, when we hear or read about “red meat” – it’s referring to the combination of all red meats (processed and unprocessed).  It’s important to distinguish between these because they could affect our cardiovascular risk differently!  I’m particularly interested in unprocessed red meat and heart disease risk.

So…what does the research tell us?

In a systematic review and meta-analysis, Micha et al. (1) concluded that unprocessed red meat did not significantly impact the risk of coronary heart disease (CHD) or diabetes.  Processed meat, on the other hand, was associated with a 42% higher risk of CHD and a 19% higher risk of diabetes.  In 2012, Micha et al. (2) performed an updated review on this topic.  After they factored in more recent studies, the authors still concluded that processed meat consumption had strong associations with CHD and diabetes; however, unprocessed red meat still had little or no association with these conditions.

In a systematic review by Lippi et al. (3), four observational studies found that higher intake of red meat was associated with an increases risk of ischemic heart disease (IHD), whereas, five studies showed red meat did not significantly increase the risk of IHD.  The researchers mentioned that, considering the mixed results of these studies, firm conclusions can not be drawn for the relationship between red meat and IHD.

A 2017 study by Wang at al. (4) looked for associations between red meat intake and non-fatal myocardial infarctions (heart attacks).  Once again, higher intake of unprocessed red meat was not found to be associated with heart attack incidence.  Higher intake of processed red meat was, however, found to be associated with increased odds of non-fatal heart attack.  I find the title of this study to be a little misleading – “Red Meat Intake Is Positively Associated With Non-Fatal Acute Myocardial Infarction…”.

A meta-analysis performed by Larsson & Orsini (5) looked to see if there was an association between red meat consumption and all-cause mortality.  In other words – does higher intake of red meat increase risk of death (from any cause)?  They found that increased consumption of processed red meat, but not unprocessed red meat, was associated with increased all-cause mortality.  The authors mentioned that we cannot overlook the fact that this association could also be explained by other differences between the subjects such as socio-economic status, fruit and vegetable intake, etc.

In 2013, Rohrmann et al. (6) analyzed data from the EPIC trial to look at the effect of meat consumption on mortality rates.  The researchers estimated that 3.3% of all deaths could be prevented if processed meat intake was kept below 20 grams per day.  This study did not include data for unprocessed meat.

Yet another study by Kappeler et al. (7) in 2013 found no association between unprocessed red meat and risk of all-cause mortality, cancer mortality, and cardiovascular mortality.  They actually found the same results for processed meat, white meat, and fish.

A more recent meta-analysis by Zeraatkar et al. (8) was published in 2019 and has received a lot of attention.  The researchers found that 3 fewer servings of both unprocessed and processed red meat per week was associated with lower risk of CVD mortality, heart attack, stroke, and type 2 diabetes.  Processed red meat, but not unprocessed red meat, was also associated with increased risk of all-cause mortality.  The authors noted, however, that the reduction in risk was very small, the certainty/quality of evidence was considered low or very low, and that there is the potential for measurement error due to confounding variables.  They conclude that its very uncertain whether a causal relationship really exists, raising questions about the validity of current dietary guidelines to reduce red and processed meats.  The same authors also analyzed randomized controlled trials and concluded that lowering red meat intake had no effect on all-cause mortality, cardiovascular mortality, heart attacks, strokes, and type-2 diabetes (9).

In a 2014 study by Abete et al. (10), processed red meat was found to increase all-cause mortality and cardiovascular mortality, but not ischemic heart disease mortality.  Unprocessed red meat had no association with total mortality and ischemic heart disease, but was shown to have a 16% increased risk of cardiovascular mortality.  The authors cautioned about the possibility of confounding factors affecting the interpretation of these results.

A 2008 study by Kontogianni et al. (11) concluded that increased consumption of red meat was associated with a 52% greater risk of acute coronary events.  However, we can’t really compare this study with those mentioned above since it did not delineate between unprocessed and processed red meat.  Also, there were many differences between the ‘high red meat’ versus the ‘low red meat’ groups, including smoking status, fruit and vegetable intake, alcohol consumption, fish intake, and more – which can also account for acute coronary syndrome risk.

In another study by Bernstein et al. (12), there was a significant correlation between red meat intake and CHD risk, when comparing those consuming the most versus the least amounts of red meat.  However, the groups that consumed more red meat also had lower activity, higher alcohol intake, higher trans fat intake, greater caloric intake, lower intake of supplements, higher blood pressure, higher cholesterol, more diabetics, and more smokers.  When these variables were controlled for, there was no longer a correlation between unprocessed meat intake and risk of coronary heart disease.

A study by Bellavia et al. (14) found that those who consumed red meat had a significantly higher mortality rate than those who did not consume red meat.  Those who consumed 200 g/d and 300 g/d lived approximately 1 year and 2 years less, respectively.  This increase in risk was attributable to processed meat intake, as non-processed meat intake was not found to have any relationship with the survival or mortality rate in this study.

The majority of studies, review papers, and meta-analyses show that there is very little or no association between unprocessed meat consumption and cardiovascular disease or all-cause mortality.  Since the quality of these red meat studies is considered low, I would conclude that unprocessed red meat is not a cause of heart disease and does not increase all-cause mortality.  There seems to be a stronger relationship between processed meat consumption and heart disease and all-cause mortality.  However, due to the nature of these studies, it’s difficult to ascertain whether processed meat is truly causing heart disease or if it is simply a marker of poor dietary and lifestyle factors that also correlate with heart disease.  Until we know more, I would suggest avoiding processed meat in favour of healthy alternatives.

Yours in health,

Dr. Michael Morsillo, H.B.Sc., N.D.
Newmarket Naturopathic Doctor
16655 Yonge St., Newmarket, ON
905-898-1844 ext. 135
dr.morsillo@gmail.com
www.drmorsillo.com

 

References:

1) Micha R, et al. 2010. Red and Processed Meat Consumption and Risk of Incident Coronary Heart Disease, Stroke, and Diabetes: A Systematic Review and Meta-Analysis. Circulation; 121(21): 2271-2283.

2) Micha R, et al. 2012. Unprocessed Red and Processed Meat and Risk of Coronary Artery Disease and Type 2 Diabetes – An Updated Review of the Evidence. Curr Atheroscler Rep; 14(6): 515-524.

3) Lippi G, et al. 2015. Red Meat Consumption and Ischemic Heart Disease. A Systematic Literature Review. Meat Science; 108: 32-36.

4) Wang D, et al. 2017. Red Meat Intake Is Positively Associated With Non-Fatal Acute Myocardial Infarction In The Costa Rica Heart Study. British Journal of Nutrition; 118; 303-311.

5) Larsson S & Orsini N, 2013. Red Meat And Processed Meat Consumption And All-Cause Mortality: A Meta-Analysis. American Journal of Epidemiology; 179(3): 282-289.

6) Rohrmann S, et al. 2013. Meat Consumption And Mortality – Results From The European Prospective Investigation Into Cancer And Nutrition. BMC Medicine; 11(63):

7) Kappeler R, et al. 2013. Meat Consumption And Diet Quality And Mortality In NHANES III. European Journal of Clinical Nutrition; 67: 598-606.

8) Zeraatkar D, et al. 2019. Red And Processed Meat Consumption And Risk For All-Cause Mortality and Cardiometabolic Outcomes. Annals of Internal Medicine; 171: 703-710.

9) Zeraatkar D, et al. 2019. Effect Of Lower Versus Higher Red Meat Intake On Cardiometabolic And Cancer Outcomes: A Systematic Review Of Randomized Trials. Annals of Internal Medicine; 171: 721-731.

10) Abete I, et al. 2014. Association Between Total, Processed, Red And White Meat Consumption And All-Cause, CVD, and IHD Mortality: A Meta-Analysis Of Cohort Studies. British Journal of Nutrition; 112: 762-775.

11) Kontogianni MD et al. 2008. Relationship Between Meat Intake And The Development Of Acute Coronary Syndromes: The CARDIO2000 Case-Control Study. European Journal Of Clinical Nutrition; 62: 171-177.

12) Bernstein A et al. 2010. Major Dietary Protein Sources And The Risk Of Coronary Heart Disease In Women. Circulation; 122(9): 876-883.

13) Wolk A. 2017. Potential Health Hazards Of Eating Red Meat. Journal of Internal Medicine; 281: 106-122.

14) Bellavia A. 2014. Differences In Survival Associated With Processed And With Nonprocessed Red Meat Consumption. American Journal of Clinical Nutrition; 100: 924-929.

15) Canada’s Food Guide. “Eat Protein Foods”. Government of Canada.  Accessed on September 14, 2020. https://food-guide.canada.ca/en/healthy-eating-recommendations/make-it-a-habit-to-eat-vegetables-fruit-whole-grains-and-protein-foods/eat-protein-foods/