Back on the merry-go-round of bad science regarding meat consumption
The question of whether meat consumption is linked to an increased risk of type 2 diabetes (T2D) has resurfaced once again, with the release of a study by Li et al. This observational study has once again set off the usual cycle of media coverage, public concern, and the subsequent critique of the research’s flaws. While the study appears to show a correlation between higher meat consumption and increased diabetes risk, it raises important questions about the true nature of this relationship and whether causality is truly at play.
Understanding the Study
Li et al. conducted a meta-analysis to explore the link between meat consumption and the risk of developing T2D, using data from over 1.9 million adults across 31 global cohorts. These participants were tracked over an average of 10 years, and the study’s findings indicated that all forms of meat consumption—unprocessed red meat, processed meat, and poultry—were associated with a statistically significant increase in diabetes risk. Specifically, processed meat consumption showed the strongest link, with a 15% increased risk for every 50g of meat consumed per day.
The study’s methodology involved self-reported data on meat consumption, and incident T2D was determined from medical records, medication use, or self-reports. While the study claims to adjust for various confounders like smoking, BMI, and physical activity, the observational nature of the data raises concerns. The primary question remains: Does meat consumption actually cause diabetes, or is this merely an observed correlation influenced by other underlying factors?
The Critical Flaw: Correlation vs Causation
As with many previous studies in this area, the key issue with the Li et al. study is that it relies on correlation, not causation. Just because two variables are associated does not mean one causes the other. In the case of meat consumption and diabetes, there are many other factors that could be contributing to the observed association. Socioeconomic status, for example, plays a crucial role in health outcomes, and processed meat is often cheaper and more accessible in lower-income populations. Individuals from lower socioeconomic backgrounds tend to have higher risks for diabetes, which may explain, at least in part, the association observed between meat consumption and diabetes.
Furthermore, individuals who eat more meat may engage in other behaviors that are associated with a higher risk of diabetes, such as smoking, drinking, or lower levels of physical activity. These behaviors could confound the relationship between meat intake and diabetes, making it appear as if meat itself is the cause of the disease, when in reality, it may be other lifestyle factors at play.
Adjustments and Limitations in the Study
Li et al. made efforts to adjust for several confounding variables, such as BMI, smoking, and alcohol consumption. However, there is a notable limitation in their approach. The study did not provide baseline data for the variables they adjusted for, which makes it difficult to fully assess the accuracy of these adjustments. Additionally, even with adjustments, the association between meat consumption and diabetes risk remained relatively weak, with hazard ratios of only 1.10 for red meat and 1.15 for processed meat. These modest increases in risk suggest that other factors are likely playing a larger role in the development of T2D.
Furthermore, the study did not account for important confounders such as socioeconomic status or macronutrient intake, which could further explain the observed associations. For instance, avoiding meat might be a proxy for other health-promoting behaviors, such as increased vegetable consumption or more regular physical activity, both of which are associated with a lower risk of diabetes.
Regional Variations and Inconsistent Results
One of the most telling aspects of the study is its inconsistency across different regions. While a positive association between meat consumption and diabetes risk was observed in European populations, no significant associations were found in populations from the eastern Mediterranean or southeast Asia. This inconsistency suggests that the link between meat and diabetes may not be universal and could be influenced by other regional factors, such as cultural eating habits, healthcare systems, or even genetic predispositions.
In particular, the study found no significant association between poultry consumption and diabetes risk, except in the European cohort. Furthermore, when the authors adjusted for other variables like cooking methods or baseline comorbidities, the association between poultry consumption and T2D risk disappeared entirely. This suggests that the link between meat consumption and diabetes risk is not as straightforward as the study implies.
The Bigger Picture: Beyond Meat Consumption
While the study by Li et al. might suggest a link between meat consumption and T2D risk, it does not provide definitive evidence of causality. Diet and disease risk are influenced by a complex web of factors, including socioeconomic status, lifestyle habits, and access to healthcare. Meat consumption is just one variable in a larger equation, and focusing too heavily on it may obscure the broader issues that contribute to the rise of T2D.
In fact, the dietary habits of individuals who consume more meat may reflect other health behaviors that are more strongly associated with diabetes risk, such as lower levels of physical activity or poorer overall nutrition. Studies that focus solely on meat consumption without considering these broader factors risk oversimplifying the issue and failing to address the root causes of T2D.
The Cycle of Media Hype and Alarmism
The publication of this study has sparked yet another round of media coverage, with headlines warning about the dangers of eating meat. However, as is often the case with such studies, the conclusions drawn from the data are far from conclusive. While it is important to examine potential links between diet and disease, it is equally important to approach these findings with skepticism and a critical eye.
The cycle of alarmism surrounding meat consumption and its alleged health risks is all too familiar. Each new study claiming a link between meat and a negative health outcome is quickly picked up by the media, leading to widespread fear and confusion. But as long as these studies fail to establish causality, the question remains: Are we truly looking at a health hazard, or are we simply seeing the latest iteration of a familiar narrative?
Conclusion
The study by Li et al. provides yet another example of how correlation can be mistaken for causation. While the data show a statistical association between meat consumption and an increased risk of type 2 diabetes, this does not mean that meat is the cause of the disease. Many other factors, such as socioeconomic status, lifestyle habits, and cultural differences, likely play a far greater role in the development of T2D. Until we see studies that can establish causality, we should be cautious in interpreting these findings and avoid jumping to conclusions about the health risks of meat consumption.
Update from Peter Attia, on 2024-08-24Source