Scientific consensus on the potential harmfulness of animal-sourced foods cannot be claimed

Dietary recommendations often advocate for limiting the consumption of animal source foods, particularly red and processed meats, as well as animal fat. Some authors even categorize animal source foods as 'less healthy' compared to plant-derived foods, and equate red meat with unhealthy foods like sugar. However, contrary to claims made by vocal public health nutritionists, these recommendations lack consensus and unanimous scientific support. 

Some experts have expressed concerns, especially for populations with high nutritional needs. They argue that these recommendations rely on incomplete data and problematic interpretations. Moreover, overly restricting animal source foods may lead to nutrient deficiencies that outweigh any potential risk of chronic disease.

Observational studies suggest that consuming certain animal-source foods may be linked to slightly increased health risks. However, these findings remain contentious, plagued by confounding factors and bias. Intervention studies have largely failed to support these associations, and biochemical research has yet to identify clear mechanisms to explain them.

Researchers recognize these limitations and caution against overinterpreting results, highlighting issues such as heterogeneity and residual confounding. Similarly, the WHO/IARC panel investigating the link between red meat consumption and colorectal cancer emphasized the role of chance, bias, or confounding and did not establish red meat as a definitive cause of cancer.

Nonetheless, some of the more influential and activistic studies and reports present unjustified causal claims and recommendations, which are then uncritically adopted in policy frameworks.

Influential organizations, including the WCRF, WHO, IARC, EAT-Lancet Commission, the Nordic Nutritional Recommendations committee, and the Global Burden of Diseases consortium, are alarmist about the potential health risks associated with red and processed meats, for which they argue restriction. While these organizations position themselves as authoritative, their claims have faced severe criticism on methodological grounds from various scientists.

Concerns include poor data quality and weak evidence. Regional inconsistencies are also notable, with cohorts in the USA often showing worse outcomes, suggesting cultural or dietary biases in the data. In contrast, the PURE study, a large global dietary cohort, indicates that unprocessed red meat should not be a target for reduction, with higher intake levels correlating with better health outcomes.

The GRADE system, the gold standard for evaluating epidemiological evidence, concludes that there is only 'low' to 'very-low' certainty that reducing red and processed meat intake improves cancer mortality, cardiometabolic outcomes, or overall mortality. Consequently, it offers a recommendation for adults to maintain rather than restrict their current consumption levels, emphasizing the importance of individual decision-making based on absolute effect estimates.

Vocal nutritionists with a strong anti-meat bias have tried to dismiss this criticism by launching an unsubstantiated smear campaign against dissident voices and by arguing that GRADE is too severe, thereby stating that they are ready to accept substandard evidence for nutritional epidemiology.

The reporting of 'relative' risks (RR) associated with the intake of animal-sourced foods in relation to health outcomes often leads to unwarranted sensationalism. These values are frequently presented without mentioning the 'absolute' risk (AR), creating exaggerated interpretations among non-experts. Even dietary guidelines tend to overlook the trivial AR reductions that come with dietary changes. 

For instance, an 18% RR increase for colorectal cancer linked to high processed meat consumption sounds alarming, but its corresponding AR increase is only 1%. To put it differently, the likelihood of someone not developing colorectal cancer during their lifetime would only shift from 94% to 93% with such a dietary change. Moreover, this virtual risk increase is based on low-certainty evidence only.