Characterizing the potential health effects of exposure to risk factors such as red meat consumption is essential to inform health policy and practice. Previous meta-analyses evaluating the effects of red meat intake have generated mixed findings and do not formally assess evidence strength. Here, we conducted a systematic review and implemented a meta-regression— relaxing conventional log-linearity assumptions and incorporating between-study heterogeneity—to evaluate the relation-ships between unprocessed red meat consumption and six potential health outcomes. We found weak evidence of association between unprocessed red meat consumption and colorectal cancer, breast cancer, type 2 diabetes and ischemic heart disease. Moreover, we found no evidence of an association between unprocessed red meat and ischemic stroke or hemorrhagic stroke. We also found that while risk for the six outcomes in our analysis combined was minimized at 0 g unprocessed red meat intake per day, the 95% uncertainty interval that incorporated between-study heterogeneity was very wide: from 0–200 g d−1. While there is some evidence that eating unprocessed red meat is associated with increased risk of disease incidence and mortality, it is weak and insufficient to make stronger or more conclusive recommendations. More rigorous, well-powered research is needed to better understand and quantify the relationship between consumption of unprocessed red meat and chronic disease.
Full Paper - https://doi.org/10.1038/s41591-022-01968-z
The observational weak relative risk studies can be pumped out infinitely, they do not inform on cause and effect sadly. The best data we have of prewesternized cultures eating meat heavy diets shows no incidence of cancer in these populations (first tribe nomads, inuit, etc). Humans have been eating meat for at least 2.5 million years, yet cancer has only jumped up to the epidemic it is today in the last 150 years. Something in the environment and diet has changed, absolutely. What is the causative factor? The anti-meat papers with weak relative risk tells me that its not the meat, we should be looking for a very strong signal (50% of people born today will have cancer in their lifetimes - 150 years ago basically nobody got cancer).
I could speculate, and I have my own theories, but we are looking for a significant change in the last 150 years as our culprit. Meat is not a new invention. Processed food, fructose, sugar, industrial food oils, pesticides in the food supply - all have bloomed in the last 150 years, I would hazard a guess and say these are the real harbingers of modern disease we need to focus on. Curiously these epidemiological food questionnaire papers don’t look at these factors, maybe because its hard to fill in a survey for sugar (its in all processed food).