Is red meat harmful?
Defending Dr. Gabrielle Lyon's statement regarding Red Meat
A popular plant based lifestyle proponent, Simon Hill, recently published a “fact check” video clip wherein he presented some scientific literature that he claimed disproved a statement made by another popular social media influencer on health, Dr. Gabrielle Lyon.
Her statement capsulized was that she knew of no randomized controlled trials to say that “eating red meat is an issue". He then presented three articles in the scientific literature that at a minimum disproved her statement that meat wasn’t harmful. He acknowledged that he couldn’t say with certainty whether Dr. Lyon was aware of those studies or the individual studies that were reviewed in the first paper, but he invited her to respond. No need. I’m doing it for her.
Here’s a link to Simon's video clip on YouTube.
The first paper Simon provides in support of his proof that red meat is harmful, is a meta-analysis entitled “Meta-Analysis of Randomized Controlled Trials of Red Meat Consumption in Comparison with Various Comparison Diets on Cardiovascular Risk Factors”. [Guasch-Ferré 2019]
Simon quotes an excerpt of the Abstract in support of his claim that red meat is harmful. However, the part of the study that Simon highlights in his video is not the finding of the meta-analysis. It’s what’s called “dictum” in Latin, meaning “something said”. The authors of the study often insert their “take” in the Introduction or Abstract at the beginning of the paper which is not the actual results of the study.
The actual result of the meta-analysis is stated in the first sentence of the DISCUSSION section, which states:
"In the present meta-analysis including 36 RCTs, relative to all comparison diets combined, red meat consumption had no differential effects on total cholesterol, LDL-C, HDL-C, apolipoproteins A1 and B, or blood pressure, but yielded lesser decreases in triglyceride concentrations."
But what about the individual studies in the meta-analysis? Simon repeatedly indicates in the video that apo-B is the only reliable biomarker for CVD risk and that a higher apo-B is indication of higher risk for cardiovascular disease. Let’s examine the ten studies that had results for apo-B to see if the red meat diet led to higher levels of apo-B when compared to the other diets.
If you don’t know how to read a forest plot, never fear, I’ve written a fairly simple explanation in an article I’ve cleverly entitled “How to read a forest plot”.
As you can see, of the ten studies that had findings for apo-B not a single one showed as statistically significant increase in apo-B. The confidence interval for each of the studies cross the line of effect meaning that none of the increases or decreases were statistically significant.
I could try sell you some “snake oil’ and tell you that the data “suggests” that eating red meat actually lowers apo-B since the pooled group mean was to the left of the no effect line. But that’s a ploy that Walter Willett has patented so I’ll leave the misleading jargon to Dr. Willett.
Bottom line, none of the studies could show that eating red meat increased levels of apo-B. Nor did the meta-analysis of the pooled data from those studies.
Red Meat Diet reduced levels of apo-B in Bergeron 2019
Simon then proposed that the 2019 article authored by Bergeron reporting the results of controlled trial supported the proposition that eating red meat resulted in unfavorable changes in apo-B. [Bergeron - 2019]
In that study, although it is accurate to state that there was a higher reduction in apo-B in the plant protein group as Simon points out, there was actually a significant reduction from baseline in all three groups, including the red meat group. The mean apo-B at baseline was 0.74 g/L in the three study arms he refers to. At study conclusion the red meat and poultry groups had experienced a 9.5% reduction in apo-B to 0.67 g/L while the plant protein group experienced a 14.86% reduction in apo-B to 0.63 g/L. All diets were beneficial in reducing the negative biomarker.
Accordingly, this study does not support the proposition that red meat is harmful since it actually lowered the apo-B level in the study. Accordingly, this study also does not disprove Dr. Lyon’s statement.
Zheng 2022 was not a Meta-Analysis
Finally, although it barely warrants a comment for reasons I’ll explain, I’ll provide a brief response on the Zheng 2022 systematic review. Contrary to Simon’s statement that this study is a meta-analysis, it is not. It’s only a systematic review as no quantitative analysis was done on the pooled data from the studies it mentions. It’s nothing more than the author’s take on several studies that were possibly cherry picked because they had conclusions that align with the author’s agenda.
And as is often done, the opinions of the author are either mistakenly or purposely put forward as if they are some type of scientific result, which in this study they are not. Specifically, the author misleadingly states, “findings from this review suggested isocaloric substitution of plant-based protein for animal-based protein was inversely associated with risk of all-cause and CVD mortality”. This is misleading because there were no “findings” in this study since no statistical analysis was conducted on the mentioned studies. Notice the word “suggested”. This is nothing more that the author’s opinion on the scientific literature.
The jury is still out on whether sources of animal protein are better than or worse than plant-based sources. And I can assure you that the answer is far more nuanced than unequivocally stating it in such broad terms. But one thing is not without question. If anyone owes an apology to someone, I’m in the camp that says Simon owes one to Dr Lyon for his misleading and sometimes wholly inaccurate “fact check” on Dr. Lyon’s statement.
