How funding influences cardiac red meat study conclusions

By Dr. Sanchari Sinha Dutta, Ph.D.Reviewed by Lauren HardakerJun 16 2025

A new review reveals how financial conflicts of interest and strategic study design shape the narrative around the real impacts of red meat on cardiovascular health, prompting calls for more transparent, independent nutrition research.

Study: Industry study sponsorship and conflicts of interest on the effect of unprocessed red meat on cardiovascular disease risk: a systematic review of clinical trials. Image credit: Sergey Ryzhov/Shutterstock.com

A study published in The American Journal of Clinical Nutrition revealed that financial sponsorship from the red meat industry and conflicts of interest may be associated with differences in scientific conclusions regarding the effects of red meat intake on cardiovascular health.

Background

Excessive intake of processed red meat is a well-known risk factor for cardiovascular disease and related mortality. This elevated risk might be due to high levels of salt, polycyclic aromatic hydrocarbons, nitrates, and nitrites in processed meat.

A healthy diet emphasizing consuming plant-based foods and restricting animal-based foods is considered beneficial for cardiovascular health. Regarding the intake of unprocessed meat, the evidence is inconclusive, with some studies reporting negative effects, some showing neutral effects, and some even reporting positive effects on cardiovascular health.

While parallels have been drawn with research funded by the tobacco and alcohol industries, which is known to influence scientific conclusions, nutrition research has also shown patterns where industry funding aligns with sponsor interests. For instance, studies funded by the red meat industry have sometimes been associated with efforts to downplay the environmental impact of livestock on climate change and planetary health.

However, prior to this study, the evidence did not conclusively demonstrate that red meat industry funding drives favorable or inconclusive findings about the association between unprocessed red meat consumption and cardiovascular health.

Given the growing attention on unprocessed red meat intake for health and environmental reasons, this systematic review was designed to assess whether red meat industry sponsorship or conflict of interest influences study findings regarding the impact of unprocessed red meat intake on cardiovascular disease risk.   

Review design

The researchers screened various electronic databases to identify randomized and nonrandomized controlled trials that investigated the impact of unprocessed red meat intake on cardiovascular disease risk factors. Unprocessed red meat refers to beef, veal, pork, lamb, mutton, horse, and goat meat that has not been preserved other than refrigeration or freezing.

The selected studies were categorized as “Red meat industry-related” if any authors declared affiliation or financial disclosure indicating a link to the red meat industry or “Red meat industry-independent” if no author declared any affiliation or financial disclosure indicating a link to the red meat industry. 

The studies were also evaluated using the Cochrane risk of bias tool for risk of bias and the GRADE approach to assess the quality of evidence, which was mostly rated as low or very low. Additionally, they were grouped by comparator type: animal protein, plant protein, refined carbohydrates, or a mix.

Study findings

The researchers systematically analyzed 44 studies, 29 associated with the red meat industry. Most selected studies compared unprocessed red meat with animal protein, plant protein, refined carbohydrates, and a combination of animal and plant protein.

About 21% and 79% of red meat industry-related studies reported favorable and neutral cardiovascular outcomes following unprocessed red meat intake, respectively. In contrast, 73% and 27% of red meat industry-independent studies reported unfavorable and neutral outcomes, respectively. None of the independent studies reported favorable cardiovascular outcomes.

Studies with financial conflicts of interest were almost fourfold more likely to report favorable or neutral outcomes than independent studies.

Study significance

This systematic review reveals that most studies not associated with the red meat industry suggest unfavorable cardiovascular outcomes of consuming unprocessed red meat. On the other hand, studies funded by the red meat industry are more likely to report neutral or favorable cardiovascular outcomes.

Red meat industry-related studies are more likely to report neutral or favorable outcomes, which may be explained by their experimental design comparing unprocessed red meat with animal protein or refined carbohydrates.

Red meat industry-independent studies, however, primarily compared unprocessed red meat with plant protein, leading to the conclusion of unfavorable cardiovascular outcomes. These observations highlight the importance of selecting a suitable comparator while assessing the impact of diet on health outcomes.

Processed meat or refined carbohydrates are known risk factors for cardiovascular disease. Comparing these food products to unprocessed meat increases the probability of favorable or neutral outcomes. This methodical choice was frequently observed in industry-related studies.

Studies not associated with the red meat industry have found that unprocessed red meat should be replaced with high-quality plant proteins to improve heart health.

The study stresses that diet effects must be interpreted in context, as dietary components are not consumed in isolation. This is referred to as the “isocaloric principle,” meaning the health impact of food often depends on what it replaces.

Plant proteins may increase the abundance of anti-inflammatory bacteria and reduce the abundance of inflammatory bacteria in the gut, potentially justifying their cardiovascular health benefits. On the other hand, animal proteins may adversely affect the gut microbiota composition and diversity, highlighting their possible adverse cardiovascular effects.

However, the study notes that these mechanisms are still under investigation, and the benefits of replacing red meat with plant proteins may be partly due to beneficial compounds in plant foods as well as the removal of potentially harmful components in red meat.

Given the observations made in this review, the researchers advised carefully interpreting the results of industry-funded studies for the sake of public health where potential conflicts of interest exist. However, they agreed that industrial funding is essential for supporting large-scale nutritional research.

Although the review highlights the significant influence of conflict of interest on study outcomes, the researchers mentioned that such influence does not necessarily imply deliberate misconduct, and researchers should not be presumed to be complicit without clear evidence.

The authors also emphasized that industry-funded studies did not differ in overall methodological quality compared to independent studies, suggesting that the choice of comparator, rather than study quality itself, may play a more critical role in shaping conclusions.

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