The Case for Eating (Some) Meat from a Longevity Perspective

by Nils Osmar. June 26, 2022. Medical Disclaimer

Anyone who reads health-related articles online is constantly subjected to claims that “meat is toxic”, “meat causes cardiovascular disease,” “meat causes diabetes”, “meat causes cancer”, and that “eating plants is the path to longevity.”

Are these claims true? If we include red meat in our diets, will our health fall apart, leading to us dying young? Most damning, does the TMAO from red meat and eggs trigger heart attacks and strokes?

Many online articles suggest that this is the case. It’s a truism, often repeated by a wide range of sources, that “We all know meat is bad for us” and “plant based diets are better” and that “if you really want to be healthy, you’ll go vegan.”

But a number of recent studies suggest that this may not be the case.

The TMAO question

Re: TMAO, online articles often claim that it’s associated with heart disease. But not all studies support this conclusion. Some suggest the opposite is true.

Here’s a quote from a Heart Research Institute article called Heart study debunks meat metabolite myth, The study they are referring to was published in the European Society of Cardiology journal Cardiovascular Research.

A metabolite linked to red meat and egg-rich diets is not the heart attack and stroke trigger many feared, new Australian research reveals.
The research team from the Heart Research Institute (HRI) and Charles Perkins Centre, The University of Sydney has debunked the widely publicized belief that trimethylamine-N-oxide, or TMAO, can clog up arteries, causing catastrophic heart problems like heart attacks and strokes.
“We’ve discovered that contrary to other research, this metabolite called TMAO, isn’t actually responsible for these common debilitating heart conditions,” says Dr John O’Sullivan, head of the HRI’s Cardiometabolic Disease Group.
“Essentially, we found no direct link between TMAO and the extent of atherosclerosis either in humans or in the laboratory,” Dr O’Sullivan explains.

Does meat cause diabetes and cancer?

According to a study published on Oct. 1, 2019, in Annals of Internal Medicine, the answer is no. An international team of researchers conducted five systematic reviews that looked at the effects of red meat and processed meat on health issues including cancer, diabetes, heart disease and premature death.

The researchers found “low” evidence that either red meat or processed meat is harmful.

Their advice was that there is no need to reduce your regular red meat and processed meat intake, and no evidence that doing so will be of benefit to our health.

About leucine, methionine and mTOR

From a longevity perspective, meat does have some potential problems. But for those who would like to include meat in their diets, there are ways to do so which can bypass these issues.

Meat is high in methionine, which is pro-aging. But eating glycine along with the meat (or eating collagen, which is high in glycine)(or eating “nose to tail”, which is also rich in glycine) prevents methionine from being harmful — because glycine detoxifies methionine. Reference: Effect of dietary glycine on methionine metabolism in rats fed a high-methionine diet.

Meat is also high in the amino acid leucine, which activates mTOR, the “growth pathway”. This is a more serious possible problem (or could be) because when mTOR is on, AMPK, the longevity pathway, is off. So eating a lot of meat could, in theory, shorten our lives, because when mTOR is turned on, AMPK is (generally speaking) turned off.
The truth, though, is that we need both mTOR activation and AMPK activation. mTOR supports growth, including the growth of new muscle; We need some mTOR activation to prevent muscle wasting and dementia, and to support our immune systems.
AMPK supports an equally important process, catabolism, a key pathway to longevity.
Too much mTOR activation is problematic. In lab studies, if the animals are fed foods high in excess calories, high in high-glycemic carbs, or high in leucine, they do tend to lead shorter lives. Animals fed diets that are lower in calories and/or low in leucine do tend to live longer – sometimes significantly longer. (Their immune systems are suppressed if their leucine is too low, but they’re protected by diseases by being in a laboratory setting.)
The truth, though, is that both animal foods and plant foods can activate mTOR. Any food that triggers an increase in insulin will at some point switch AMPK off and mTOR on. When I was vegan, I ate foods like rice, which is very high in carbohydrates and low in nutrients, and fruit salads. My mTOR activation was no doubt constant as a result.
So if meat is “guilty” of turning on mTOR, the foods eaten by most vegans can also do so. But again – mTOR is not “bad”. We just don’t want it in excess.

Learning from the Acciarolins

I eat a generally Mediterranean diet, which has foods from plant, animal and fungal food sources. I eat lots of greens, root vegetables, berries, lentils, and cruciferous vegetables. I also eat sardines, poultry and red meat, which are high in leucine and TMAO.

My diet is higher in animal foods than some Mediterranean diets (though not the Acciarolin diet) I have zero concerns about the TMAO or leucine or methionine somehow harming me.

The people of Acciaroli are an interesting case study. They have the highest rate of Centenarians of anywhere in the world – 75 times higher than most places, and 25 times higher than the “blue zones. They do not “just eat a Mediterranean diet.” They grow their own gardens, raise and eat their own chickens and rabbits, eat eggs and cheese, and they practically live on sardines, anchovies and rosemary. They also have the highest rate of 110 year olds of anywhere in the world. See article: Acciaroli and the Secret of Living Longer and Better

I avoid meat from factory farms, both for ethical and health reasons. I eat grass-fed and grass-finished meat from animals who led good lives, protected and cared for and protected from natural predators on small family farms.

My vegan days

I was vegan for three years. I had hopes that this would improve my health.

I liked being vegan at first. I came to appreciate plant foods I’ve never eaten before. I initially felt good, which may be because, since vegan diets tend to lower in protein that omnivorous diets, they can promote autophagy, which cleans debris from our cells. They can also promote fat loss under some circumstances.

But the longer I was vegan, past a certain point, the more my health went downhill. During my vegan years:

I lost muscle. I got physically weaker, and easily exhausted.
My eyesight went down hill.
My teeth started hurting.
My joints ached.
My skin started looking sickly.
I developed mood problems and memory problems.
I lost interest in sex.
I initially lost weight, then started adding body fat and became obese.

Adding meat and other animal foods back into my diet restored my health almost overnight.

When I mentioned this to folks in my vegan community, a response I often got was that I must have been “doing veganism wrong”. They would then go on to make wildly different recommendations, such as “You should have been eating more soy. You should have been eating less soy. You should have been taking more supplements. You were taking too many supplements. You were eating too many greens. You obviously needed more greens. You should go fruitarian, like the Banana Girl. But whatever you’re doing, the fault isn’t with the vegan diet, it’s with you, you’re doing it wrong.”

I would reply (to those who would listen) that I had tried many different versions of the vegan diet during my three years, struggling to get the nutrients I needed from plants alone. I’d consulted with vegan nutritionists and medical professionals. None of their suggestions had helped. My health had still gone downhill…. and been instantly restored when I started eating meat again.

I wondered at that point why I had struggled so hard to make an unworkable diet work.

Similar things eventually happened to most of my vegan friends. Several developed memory and mood problems. Some stayed at a healthy weight, but some got fat. Some got emaciated. Some developed diabetes. The ones who added animal foods back into their diets, like me, found their health almost immediately improving. I learned from these experiences that the notion that veganism is the best path to health for everyone is simply not true.

“Fasting” from meat – and from vegetables

When I talk about my experience with veganism, people sometimes assume that I’m hostile to it and would never be vegan again. But this isn’t quite true. I sometimes do vegan weeks – and carnivore weeks. I consider both to be types of fasts.

When people hear the word “fasting”, they tend to think of water fasting. But a “fast” can be a break from any food group or nutrient.

I sometimes do water fasts for a day or a few days, (I’m currently doing two 36 hour water fasts most weeks.)
I sometimes do fasting mimicking diets. FMDs are are totally vegan, and extremely low in protein and carbs, and have almost zero grams of leucine. They give most of the benefits of water fasting, while providing a baseline of nutrients.
I also sometimes do “meat fasts” in which I only eat meat for a day, or a few days. My mTOR will definitely be activated on these days… and I’ll lose body fat, feel unusually sharp and clear, my blood glucose will be fantastic, and my cholesterol invariably improves when I’m eating only meat.
I’ve found all of these approaches, in small doses like this, to be beneficial to my health.