Abstract
Background
Experimental research on the link between unprocessed red meat and cardiovascular disease risk is inconsistent and may differ according to the financial interests of red meat industry sponsors.
Objectives
This study aims to assess whether studies sponsorship or conflicts of interest with the red meat industry are associated with reported outcomes of unprocessed red meat consumption effect on risk factors for cardiovascular disease.
Methods
PubMed, Cochrane Library, and Scopus were searched from the inception of the databases to 3 March 2024. Studies were classified as “Red meat industry-related” if any of the authors declared affiliation or financial disclosure indicating a link to the red meat industry; or “Red Meat industry-independent.” Reported outcomes were independently graded as favorable, neutral, or unfavorable. Studies were also categorized by type of control group. The quality of evidence for each outcome was evaluated using the Grading of Recommendations Assessment, Development and Evaluation approach.
Results
A total of 44 studies were included, of which 66% had a link to the red meat industry. All independent studies reported either unfavorable (73.3%) or neutral (26.7%) cardiovascular outcomes when consuming unprocessed red meat. Conversely, all studies related to the red meat industry reported either favorable (20.7%) or neutral (79.3%) cardiovascular outcomes for red meat intake. A total of 69.6% of trials (16 of 23) showed a neutral effect of unprocessed red meat compared with other animal proteins, whereas 70% (7 of 10) reported an unfavorable effect compared with plant proteins. Studies with conflicts of interest were nearly 4 times more likely to report “Favorable/Neutral” outcomes compared with independent studies (odds ratio 3.75, 95% confidence interval: 1.62, 8.67).
Conclusions
Our findings highlight that using animal protein as a comparator in industry-funded studies, with quality of evidence rated as very low to low, may underestimate the cardiovascular benefits of reducing red meat intake. Most studies without conflicts of interest with the red meat industry suggested an unfavorable effect of unprocessed red meat consumption on risk factors for cardiovascular disease.
