Cholesterol and Red Meat
For 70 years the American Heart Association has told us to avoid dietary intake of saturated fat and cholesterol. However, rightly so, these assumptions have come under heavy scrutiny in recent decades.
In 2015 the American Heart Association (AHA) recommended less than 10% of daily calories come from saturated fat (1). That recommendation has since been reduced to 5% (2).
However, in 2009 a study was published suggesting that 72% of heart attack patients had “recommended targets for LDL cholesterol.” (3). Sample size is important if a study is going to be used to recommend public / national policy. In this case the sample population (n) was over 130,000 and accounted for “59% of total hospital admissions for heart attack at participating hospitals (from 2000 - 2006).”
It’s worth saying over, and over, again, that “correlation (linked / realted / association) is not causation.” For example, living is positively correlated with dying — the longer you live, the more likely you are to die.
However, without correlation we can never have causation. If we have identified a true cause or contributing factor, we will always see a positive correlation. It’s hard to argue that cholesterol causes heart attacks when 72% of cases are an exception. A policy that is wrong more than 2/3 of the time has stood for 70 years and counting.
To make matters worse for AHA’s recommendation, the UCLA study found that 21% of heart attack patients were actively taking “lipid-lowering medications before admission.” That means taking cholesterol lowering medications is almost as risky (statistically) as having elevated or high cholesterol (21% vs 28% of heart attack patients).
I the Spring of 2024 there were more papers published to vindicate red meat consumption. First, “The relationship between processed meat, red meat, and risk of cardiovascular disease and Type 2 diabetes” (4) concluded that…
“The study discerned no observable impact of red and processed meat consumption on CAD, hypertension, stroke, and T2DM. The findings of this study challenge the prevailing conventional perspective in the field.”
Effect size is an important consideration as well because if it’s too small, let’s say a correlation (r) of +/- 0.1, that’s pretty vague and it’s likely that there are “covariates” or “confounding variables” even if the results are “stastically significant” (p-value).
On the other hand, a correlation of +/- 0.7 is very strong and +/- 1.0 is proportionately perfect. In most statistical cases, a p-value (p) of < 0.05 is considered “statistically significant”, because it indicates a < 5% chance of the results occurring at random.
The 72% failure rate of AHA’s recommendation is a literal shot in the dark. Even if the numbers were fudged to show a strong correlation — without significance, the “link” is useless.
Lastly, a paper titled “Red and processed meat intake and risk of cardiovascular disease” (5) concluded that…
“This MR study demonstrated no significant causal relationships between red/processed meat intake and the risk of the four CVD outcomes examined. Further investigation is warranted to confirm these findings.”
While this paper has different authors, it appears to be working with the same dataset. We can see that for the most part, 8/12 factors, processed meat, beef, and lamb intake actually lower the risk of cardiac events. In the case of lamb raising hazard ratios, there are a lot of things a person can do to raise / lower their risk a meager 4% to 6% (e.g. HRs of 1.04 and 1.06).
Regarding the beef-and-stroke risk factor, there could certainly be lifestyle factors contributing to the elevated risk. However, this isn’t so much a flaw of this particular study design as it is a limitaiton of all epidemiology (correlation) studies. However, what we can observe is that the same lifestlye factors would apply across all types of meat consumption.
This study isn’t comparing beef-eaters vs. pork-eaters vs. lamb-eaters. It’s comparing beef-as-a-factor, lamb-as-a-factor, pork-as-a-factor within the same population that eats all three. This leads me to believe there are concerns with how the pork is being raised / what the pigs are eating as an independent variable — particualrly because pigs are monogastric animanls vs. cows and lamb.
In conclusion, there isn’t any reason to fear red meat consumuption from (particularly from beef and lamb), and there is every reason to be skeptical of AHA’s recommendation to lower cholesteral and saturated fat intakes. If we really want to get into the weeds, we can discuss fudning sources for AHA’s recommendations as well as compare the correlation between AHA’s recommendation and frequency of cardiovascular disease.
