Eat Less Red Meat, Scientists Said. Now Some Believe That Was Bad Advice

Moderation is great so long as you don’t overdo it.

His hands may well be squeaky clean. But one would be within one’s rights to be a little suspicious. Considering.

Not sure what that has to do with anything. He doesn’t need to eat lots of meat in order to take money to support the eating of meat. I’m pretty good at work/other stuff separation. I bet other people manage, too.

Anyway! As noted, I don’t really have a dog in this fight, so I’ll let the people who care about meat’s effect on health take it from here.

Exactly . You have to know yourself. Everybody is different. What works for some won’t work for others…

Nutritional science is not different than any other science as it evaluates the best existing science which exists at each time point and makes a hypothesis which is good until proven otherwise. The current existing data regarding red meat consumption and certain cancers indicates that there is a possibility of a close link between them. The newly published study doesn’t have significantly different data but they have different interpretations which are criticized by many of their colleagues. Which is nothing bad but not a reason to change any recommendations regarding red meat consumption - it would be the same as suddenly saying there is no global warming just because a few scientists have a different interpretation even though >99.9% of all other scientists disagree with them. The reason why a lot of people/media jump on this “news” is that changing eating habits is sometimes difficult (even though most data support it) and so people looking for excuses, including such questionable papers to not change anything.

Nutrition is unlike most science in that you can’t conduct controlled experiments on human diets. And it’s bad science to make strong recommendations on low-certainty evidence.

Our weak recommendation that people continue their current meat consumption highlights both the uncertainty associated with possible harmful effects and the very small magnitude of effect, even if the best estimates represent true causation, which we believe to be implausible. …

The guideline panel’s assessment was based on the available evidence regarding values and preferences suggesting that the majority of individuals, when faced with a very small and uncertain absolute risk reduction in cardiometabolic and cancer outcomes, would choose to continue their current meat consumption. People considering a decrease in their meat consumption should be aware of this evidence. …

Regarding the uncertainty of the evidence, randomized trials were limited by the small differences in meat consumption between the intervention and control groups, whereas observational studies were limited in the accuracy of dietary measurement and possible residual confounding related both to aspects of diet other than red meat and processed meat consumption and nondietary confounders, making decisions regarding meat consumption particularly value- and preference-dependent. … our panel was not unanimous in its recommendation: Three of the 14 panel members favored a weak recommendation in favor of decreasing red meat consumption.

https://annals.org/aim/fullarticle/2752328/unprocessed-red-meat-processed-meat-consumption-dietary-guideline-recommendations-from

https://annals.org/aim/search-results?q=Johnston+meat&allJournals=1&fl_IsJCA=false&SearchSourceType=1&exPrm_qqq={!payloadDisMaxQParser+pf%3DTags+qf%3DTags^0.0000001+payloadFields%3DTags+bf%3D}"Johnston+meat"&rg_ArticleDate=10/01/2019%20TO%2010/01/2019

You are just repeating the NutriRecs statements which are heavily criticized as not scientifically sound and the large majority of scientists in the field disagree with them (as you can see from the quotes below one of the authors of the meta-analysis pretty much says that the authors of this recent questionable paper have pretty much no clue what they are doing - which is a very harsh and unusual criticism between scientists and shows the skepticism about the quality of this new paper throughout the scientific community ). I understand that you don’t want to change any of your food preferences but that doesn’t mean you can’t ignore the current science and make up things (I know it is hard to believe in a Trump world). You have to come up with more than just repeating the NutriRECS paper and bring stronger arguments:

It seems the panel’s recommendation was based on four factors: (1) The observed effects are very small; (2) The quality of evidence is very low; (3) Meat eaters enjoy meat and won’t change their behaviors; and (4), Environmental impact was considered “outside of the scope” of their guideline.

All four of these considerations are problematic. First, the effect estimates may seem small because the unit of exposure (3 servings/week) is small. However, the potential health benefits of reducing consumption would be much larger for individuals consuming 1 serving/day of red meat or more (among approximately 1/3 of US adults).* Based on their meta-analyses of large cohorts, dietary patterns with a moderate reduction in red and processed meat consumption were associated with lower total mortality by 13% (95% Confidence interval 8% to 18%), CVD mortality by 14% (6% to 21%), cancer mortality by 11% (4% to 17%), and type 2 diabetes risk by 24% (14% to 32%). These risk reductions are substantial at both individual and population levels. We currently spend tens of billion dollars per year on screening and treating risk factors for cardiovascular disease and diabetes that have benefits of this magnitude.

The second rationale used by the panel is that although red meat and processed meat consumption is associated with adverse health outcomes, the quality of evidence is too low. The authors applied a GRADE (Grading of Recommendations Assessment, Development and Evaluation) criteria, which resulted in all observational studies receiving “low- or very-low” scores for “certainty of evidence,”[2-4] due to potential for confounding. This should come as no surprise, since GRADE criteria were mainly developed for evaluating evidence from drug trials. Unlike drugs, dietary, lifestyle, and environmental factors are typically not amenable to large, long-term randomized clinical trials. For this reason, modified criteria have been developed. For example, HEALM (Hierarchies of evidence applied to lifestyle Medicine), or the criteria developed by the U.S. Department of Agriculture or the Word Cancer Research Fund would have been more appropriate.

Previous meta-analyses have rated the strength of evidence from large cohort studies as “moderate” if the studies meet several criteria: consistent finding across multiple cohorts, large number of participants and long-duration of follow-up, low dropout rates, and a dose-response relationship. This is clearly the case for most of the effect estimates. Many reviews also upgrade the rating of evidence if data from randomized trials show effects on risk factors for the diseases being studied. An example of this is when evidence indicates that red meat increases blood levels of LDL cholesterol when compared to plant sources of protein. [9]

Relatedly, Dr. John Sievenpiper, professor in the Department of Nutritional Sciences at the University of Toronto and co-author on one of the meta-analyses, strongly disagreed with the panel’s conclusions and recommendations:

Unfortunately, the leadership of the paper chose to play up the low certainty of evidence by GRADE as opposed to the protective associations that directly support current recommendations to lower meat intake…Very few nutritional exposures are able to show associated benefits on the big three of all-cause, cardiovascular, and cancer mortality as well as type 2 diabetes. The signals would be even stronger if one considered substitution analyses with plant protein sources or investigated dose-response gradients which are used to upgrade data by GRADE, both of which I had requested. Unfortunately, I never saw the galley proofs to ensure that these changes had been made.

These statements raise serious concerns about the methodology of the study, and suggest that the “very low” evidence grade given to high-quality cohort studies is inappropriate. If the same procedure were used to evaluate the evidence for other dietary (such as low consumption of fruits and vegetables, high consumption of sugary beverages), lifestyle (such as physical inactivity and inadequate sleep), and environmental (such as passive smoking and air pollution) factors, none of the current recommendations on these factors would be supported by high- or even moderate-quality evidence. Basically, the foregone conclusion would echo that of this new report: that people should ‘eat whatever they want and do whatever they want;’ no need to bother with the systematic reviews and meta-analyses.

1 Like

A similar study regarding smoking would surely result in a unanimous strong recommendation based on high-certainty evidence.

At least you admit that you don’t have any other good arguments on the topic

Speak for yourself.