Does reduction in red meat consumption improve health?

Feb. 01, 2020

The recent compilation of five articles in the Annals of Internal Medicine regarding the benefits of reducing meat consumption by three servings a week was both controversial and surprising: controversial because it recommended that a person eating processed/red meat should continue the current rate of consumption because reducing intake by three servings a week, as the authors concluded, would not lower the risk of cardiovascular disease or cancer; surprising because this series of studies showed that a lower consumption of processed/red meat was associated with a significant reduction in total mortality, cardiovascular mortality, cancer mortality and incidence of type 2 diabetes mellitus.

All five articles were authored using the guideline recommendations from the Nutritional Recommendations and Accessible Evidence Summaries Composed of Systematic Reviews (NutriRECS) consortium, an international self-organized group with a self-proclaimed goal of producing "rigorous evidence-based nutritional recommendations adhering to trustworthiness standards."

The analysis included a large number of studies comprising a tremendously large number of subjects:

  • For cardiovascular outcomes (cardiovascular disease, stroke and myocardial infarction) and type 2 diabetes mellitus, 23 cohort studies with 1.4 million participants
  • For adverse cancer outcomes, 31 cohorts with 3.5 million participants
  • For overall lifetime cancer mortality, 17 cohorts with 2.2 million participants
  • For the risk of adverse cardiometabolic and cancer outcomes, 70 cohort studies with just over 6 million participants

The authors assessed the risk of adverse cardiometabolic outcomes on the basis of an average of 10.8 years of follow-up, and adverse cancer outcomes over a lifetime. In all groups, a statistically significant reduction was found in the major endpoints when processed/red meat consumption was reduced. This data is consistent with prior studies showing that processed/red meat consumption is associated with increased total and cardiovascular mortality.

Some questions persist

Why did the authors conclude that reduced consumption of processed/red meat does not improve health?

The authors explained that their conclusion to not recommend reduction of red meat consumption was based on the following factors:

  • Though there was a small absolute risk reduction based on a decrease of three servings a week, the certainty of evidence for a reduction of adverse health outcomes associated with meat consumption was low.
  • People valued and preferred eating meat.
  • The panel focused exclusively on health outcomes associated with meat consumption and did not consider animal welfare and environmental issues.

Thus, the authors stated that "taken together, these observations warrant a weak recommendation to continue current levels of red meat and processed meat consumption."

Is reduction of three servings of processed/red meat a week a large amount?

A reduction of three servings a week equals 9 ounces, or 1.3 ounces a day, which may be interpreted as a minimal reduction equivalent to one less bite of processed/red meat a day. In addition, the analysis did not delineate whether the baseline consumption of meat was high or low (for example, more than 14 servings or less than seven servings a week).

Did these findings include relevant recent randomized trials that assessed benefits of a healthy diet?

No. These studies excluded two randomized trials evaluating the Mediterranean diet: the Lyon Heart Study in secondary cardiovascular disease prevention, and the PREDIMED study in primary prevention.

How do these recommendations potentially affect the environment?

Studies from the U.S. Department of Agriculture and a study published in Environmental Health in 2013 have shown that compared with a typical Western diet, reducing processed/red meat to three ounces a day can reduce an individual's environmental "footprint" (including land, energy and water consumption along with gas emission) by 72%.

Do the findings support the authors' recommendations?

The authors' meta-analyses of dietary patterns showed that a moderate reduction in processed/red meat consumption was associated with lower total mortality (13%; CI95% = [8%, 18%]), lower cardiovascular disease mortality (14%; CI95% = [6%, 21%]), lower cancer mortality (11%; CI95% = [4%, 17%]) and a lower risk of type 2 diabetes mellitus (24%; CI95% = [14%, 32%]). Some may interpret these results as clinically significant even though the authors did not.

Almost all nutritional studies are observational; it is impossible to conduct long-term, randomized, blinded dietary trials, making it difficult to formulate exact guidelines. Nevertheless, it would seem prudent based on the totality of trial evidence to continue to adhere to current dietary guidelines.

For more information

Johnston BC, et al. Unprocessed red meat and processed meat consumption: Dietary guideline recommendations from the Nutritional Recommendations (NutriRECS) consortium. Annals of Internal Medicine. 2019;171:756.

Sáez-Almendros S, et al. Environmental footprints of Mediterranean versus Western dietary patterns: Beyond the health benefits of the Mediterranean diet. Environmental Health. 2013;12:118.