Study Finds Eating Meat Increases Risk of Cardiovascular Disease

Norrina Allen, PhD

Spurred by the results of a controversial review published last fall, new data from one of the most comprehensive studies of its kind is shedding further light on the negative impact consuming meat can have on a person’s cardiovascular health.

The analysis, which included data from multiple studies with 29,000 participants followed over the span of 3 decades, revealed consuming 2 or more servings of meat per week—including red and processed meat, as well as poultry—was linked to a 3 to 7% increase in the risk of cardiovascular disease.

"It's a small difference, but it's worth trying to reduce red meat and processed meat like pepperoni, bologna and deli meats," said lead investigator Norrina Allen, PhD, associate professor of preventive medicine at Northwestern University Feinberg School of Medicine, in a press release. "Red meat consumption also is consistently linked to other health problems like cancer."

Using data from the Lifetime Risk Pooling Project, which contained information from the ARIC study, CARDIA study, Cardiovascular Health Study, Framingham Heart Study, Framingham Offspring Study, and the MESA study, Allen and a team of colleagues from Northwestern Medicine and Cornell University sought to evaluate associations of processed meat, unprocessed red meat, poultry, or fish intake with incident CVD and all-cause mortality. From these 6 prospective cohort studies, investigators identified a cohort of 29,682 participants—all of whom were free of CVD at baseline and had self-reported total caloric intake between 500 and 6000 kcal per day.

The primary dietary exposures for the analyses were processed meat, unprocessed red meat, poultry, or fish intake—investigators noted fish intake also included shellfish. A serving was defined as 4 ounces of unprocessed red meat or poultry or 3 ounces of fish. For processed meat, 1 serving was defined as of 2 slices of bacon, 2 small links of sausage, or 1 hot dog.

Assessments of participants' dietary intake were performed through use of a validated food frequency questionnaire or diet history and only baseline dietary data was used in the analyses.

Covariates for the study included age, sex, race, educational level, smoking status and pack-years, alcohol intake, physical activity, medication use, medical conditions, BMI, blood pressure and serum lipid levels. Allen and her team of fellow investigators noted BMI, blood pressure, and serum lipid levels were measured according to standard protocols while the other variables were self-reported.

The primary objective of the analyses was to determine the hazard ratio (HR) and absolute risk difference (ARD) for incident CVD and all-cause mortality based on each additional intake of 2 servings per week for monotonic associations or 2 servings compared to 0 servings per week for nonmonotonic associations. Investigators also hoped to examine associations of processed meat, unprocessed red meat, poultry, or fish intake with incident CVD and all-cause mortality in various subgroups stratified by age, sex, race, education level, and multiple other variables.

Allen and colleagues point out the associations of processed meat, unprocessed red meat, poultry, or fish intake with incident CVD and all-cause mortality were monotonic (P value for nonlinearity was .25 or greater), except for nonmonotonic association between process meat intake and incident CVD (P value for linearity was .006).

A total of 562,624 follow-up years were included in the analysis—during which 6963 incident CVD events and 8875 all-cause deaths occurred in the 29,682 person cohort. Specifically, 2687 coronary heart disease events, 1740 stroke events, 2366 heart failure events, and 170 other CVD deaths were observed by investigators. The median follow-up duration was 19 years.

When examining incident CVD, results of the fully adjusted analysis revealed consumption of 2 servings of processed meat (adjusted HR, 1.07 [95% CI, 1.04-1.11]; adjusted ARD, 1.74% [95% CI, 0.85%-2.63%]), unprocessed red meat (aHR, 1.03 [95% CI, 1.01-1.06]; aARD, 0.62% [95% CI, 0.07%-1.16%]), or poultry (aHR, 1.04 [95% CI, 1.01-1.06]; aARD, 1.03% [95% CI, 0.36%-1.70%]) per week was significantly associated with incident CVD. The same analysis revealed fish intake was not significantly associated with incident CVD (aHR, 1.00 [95% CI, 0.98-1.02]; aARD, 0.12% [95% CI, −0.40% to 0.65%]).

In regard to all-cause mortality, results indicated significant associations between intake of processed meat (aHR, 1.03 [95% CI, 1.02-1.05]; aARD, 0.90% [95% CI, 0.43%-1.38%]) or unprocessed red meat (aHR, 1.03 [95% CI, 1.01-1.05]; aARD, 0.76% [95% CI, 0.19%-1.33%]) with all-cause mortality. Conversely, intake of poultry (aHR, 0.99 [95% CI, 0.97-1.02]; aARD, −0.28% [95% CI, −1.00% to 0.44%]) or fish (aHR, 0.99 [95% CI, 0.97-1.01]; aARD, −0.34% [95% CI, −0.88% to 0.20%]) was not significantly associated with all-cause mortality.

Results of the study indicated patients eating 2 or more servings of red meat per week were at a 3 to 7% high risk of CVD and premature death. Meanwhile, patients who ate 2 or more servings of poultry per week were at a 4% higher risk of CVD but investigators did not feel the evidence was sufficient enough to make a recommendation condoning its consumption—no associations between fish intake and CVD or mortality were apparent based on the results of the current analyses.

"Fish, seafood and plant-based sources of protein such as nuts and legumes, including beans and peas, are excellent alternatives to meat and are under-consumed in the U.S.," said investigator Linda Van Horn, professor of preventive medicine at Feinberg who also is a member of the 2020 US Dietary Guidelines Advisory committee, in the aforementioned release.

This study, titled “Associations of Processed Meat, Unprocessed Red Meat, Poultry, or Fish Intake With Incident Cardiovascular Disease and All-Cause Mortality,” was published online in JAMA Internal Medicine.