Meat or not?

Research published in 2014 showed that the correlation between meat consumption and coronary artery disease was weak. It got a lot of press. What got less press was when the authors were forced to publicly correct their errors a short while later:

From https://www.sciencemag.org/news/2014/03/scientists-fix-errors-controversial-paper-about-saturated-fats:

When a paper published on 17 March questioned whether fats from fish or vegetable oils are healthier than those in meat or butter, it quickly made headlines around the world; after all, the study seemed to debunk a cornerstone of many dietary guidelines. But a new version of the publication had to be posted shortly after it appeared on the website of the Annals of Internal Medicine to correct several errors. And although the study’s first author stands by the conclusions, a number of scientists are criticizing the paper and even calling on the authors to retract it.

Even if the the earlier research showing that the correlation between meat consumption and coronary artery disease is weak had been completely valid, it was still focused on an endpoint of average mortality and morbidity. In other words, this only proves that meat eaters are no more likely to die of heart disease the non-meat eaters not that they lived a long and healthy live as a result. Although not dying interests me, my main interest is live both long AND well.

A study in the Annals of Internal Medicine in 2019 appeared to lend further support to the position that consumption of meat has no ill health effects. This one basically said people did not need to concern themselves at all with meat consumption. That the benefits were so small, they could consume all kinds freely. Like many such articles, this one was recorded in the press in a very and critical fashion. However, the article begins with what is essentially a disclaimer:

The panel suggests that adults continue current unprocessed red meat consumption (weak recommendation, low-certainty evidence). Similarly, the panel suggests adults continue current processed meat consumption (weak recommendation, low-certainty evidence).

As several critics at the time noted, one study does not undo decades of prior research. Other more recent research in 2020 showed that the consumption of meat is a risk factor for increased heart disease and death risk. The study that showed meat caused cancer was dismissed by some as only referring to processed meat, but that is not accurate. From the study itself:

A large study links red AND processed meat with higher risk of heart disease and death. Eating two servings of red meat, processed meat or poultry — but not fish — per week was linked to a 3 to 7 percent higher risk of cardiovascular disease. Eating two servings of red meat or processed meat — but not poultry or fish — per week was associated with a 3 percent higher risk of all causes of death.

As is well-know, both blue zone and centenarian studies suggest that a vegetarian or even vegan diet is a common factor in those who achieve extreme longevity without significant disease or debility. Some people have tried to dismiss these studies as being disingenuous because many of the population studied eat at least small amounts of meat and animal fat. However, the fact is that there were no premodern vegan cultures that we are aware of and pure vegetarianism was not in most cultures. 

So, it’s a given that all humans are at least opportunistic carnivores (as are almost all other primates). And, perhaps not without good reason. There’s a decent amount of evidence that a certain minimum amount of animal food is beneficial because of certain nutrients that would otherwise be difficult to obtain, such as vitamin K-2, vitamin D, and essential fatty acids. That being said, it is a true observation that meat is more of a side dish than a main course in many ethnic cuisines, most of which are primarily plant-centric.

Perhaps the most compelling piece of evidence, given my current interest in the role of the microbiome in human health is that high overall fat consumption, and especially high saturated fat consumption, appear to promote a microbiome that is pro-inflammatory. From the International Journal of Food Sciences and Nutrition:

Based upon evidence to date, we believe that high-fat diets and SFA consumption should be avoided, and MUFA and omega-3 PUFA intake should be encouraged in order to regulate gut microbiota and inflammation, promoting body weight/fat control.

So, with all this in mind, Harvard convened a panel of experts to review the conflicting research and determined that there were nuances of the data that had not been properly disseminated by the mainstream media. Specifically, that those who reduced their saturated fat intake and showed a similar or worse incidence of heart disease were replacing their saturated fat calories with refined carbohydrates. On the other hand, people who replaced their saturated fat with mono- and poly- unsaturated fat had better health outcomes than people who ate a diet higher in saturated animal fat. This is supportive of a Mediterranean-style diet.

From https://www.hsph.harvard.edu/nutritionsource/2014/05/15/saturated-or-not-does-type-of-fat-matter/:

The overarching message was that when it comes to the health values of various fats, it’s about substitution. If you remove one type of fat, what are you replacing it with? Cutting back on saturated fat can be good for health if people replace saturated fat with good fats, especially, polyunsaturated fats. If you remove saturated fat and replace it with refined carbohydrates, there will be a detrimental effect. Moreover, we need to think about food quality – including food sources, and dietary patterns – rather than on nutrients alone.

We also cannot rule out the possibility that individual variation due to genetics and epigenetics may factor in here. some people may believe more genetically tolerant of saturated fat and possibly even thrive on it. It is unclear at this time who those people are and whether they also would benefit from reducing their saturated fat intake.

Ben Greenfield, who has been diving deep into nutrition research and biohacking for many years, has recently settled on the following prescription for a maintenance diet:

Mediterranean with a decreased emphasis on carbohydrates and more emphasis on fats. In addition, he recommends traditional methods of grain and bean processing to enhance digestion, many of which have been detailed by the Weston Price foundation (sprouted, soaking, and fermenting). Finally, he believes all of this should be modified with respect to one’s actual ancestry. In other words, a Chinese person can eat such a diet that was comprised of their traditional foods but still be compositionally equivalent to a Mediterranean diet. Dive deep on Ben’s blog.

My personal opinion at this time is that following the Harvard recommendations or adopting a Mediterranean diet or following advice like Ben Greenfield has on his website is a safe course of action for just about anybody. Then, from that baseline, you can make adjustments that may be more or less amenable for your biochemical individuality.