A Common Sense Defense of Animal Fat

When one looks in the books and on the internet about a "paleolithic-style" or "evolutionary-based" diet, one will likely be confused at the end of it. Some will focus on what Kurt Harris calls "paleo re-enactment" - meaning we should be hunting wild boar, digging up roots, and honey is okay. (When I first told a friend of mine, who happens to be a gastroenterologist at Johns Hopkins, about my interest in paleolithic diets, she remarked, "The only guy I ever saw on a paleo diet was pooping leaves and blood." Take that as an object lesson, paleo re-enactors, don't forage unless you know what you are doing!). Some paleo folks will be (once again using Kurt Harris' term - he has a knack for them), "pc-paleo" - meaning low fat paleo. Loren Cordain and Boyd Eaton are scientists and paleolithic nutrition pioneers, and their first look at the research focused on the fact that animals in the wild tend to be leaner than our domesticated animals. Cordain's The Paleo Diet: Lose Weight and Get Healthy by Eating the Food You Were Designed to Eat and The Paleo Diet for Athletes: A Nutritional Formula for Peak Athletic Performance will both advocate a lower-fat approach. Notice both were published prior to 2007. And as this is where the research was headed at the time, the "paleo" diets studied in diabetics by Staffan Lindeberg and others were relatively low-fat and sometimes a little weird - not sure how many of us foraged for canola oil and mayonnaise. But there you go. That's where an IRB gets you, I guess.

What's so important about 2007? Well, that's when Good Calories, Bad Calories: Fats, Carbs, and the Controversial Science of Diet and Health (Vintage) came out. I think Taubes' work is incredible and amazing, and required reading for any health professional or nutritionist. However, I do believe he focuses a bit too much on the carbohydrate hypothesis as the cause of Western Disease. He does, however, do a heck of a lot to exonerate fat.

Since 2007 and "Good Calories, Bad Calories", there has been the advent of what many now call "primal" style paleo, exemplified best by Mark Sisson's excellent book, The Primal Blueprint: Reprogram your genes for effortless weight loss, vibrant health, and boundless energy. Like Stephan Guyenet, I do think Mark is a little too hard on the carbohydrates (starch has a lot in common with, but ultimately is very different from sugar. This could be its own post, but if you have the time, I highly recommend this youtube video of a lecture by Robert Lustig, a pediatrician and obesity expert. He has a rather strange idea of what a paleo diet is, but hey, doesn't everyone?).

Anyway, the "primal" folks love fat, real food, and allow for some "sensible indulgences" such as high fat dairy, dark chocolate and red wine. And it is rumored that even Loren Cordain is more pro-fat than he used to be. Anthropological reports from all over the world will show us that our ancestors favored the fatty cut of meat, anyway, leaving carcasses and the lean meat to rot, and savoring the glands, liver, brains, and marrow, all high in saturated fat (1)(2)(3). In fact, when our ancestors were forced to survive on lean meat alone, they endured a life-threatening condition called "rabbit starvation." These symptoms of fatigue, weakness, diarrhea, hunger, headache, and low blood pressure and heart rate come from a diet of too much protein, and can be ameliorated by substituting some of the protein with carbohydrates or fat.

I've been told most of my life that animal fat is bad for me. The scientific story why this is not true is explained in exhaustive detail in a number of different, excellent books (including GCBC, but also Eat Fat, Lose Fat: The Healthy Alternative to Trans Fats) I especially like Mary Enig, as it seems to me she is the researcher primarily responsible for finally getting the FDA to come down against the nutritional horror that is industrial trans fats.

There are two, final scientific arguments against saturated ("animal") fats, in this case palmitic acid, that are not addressed in full by any of the previous sources I've named above. One is that a high amount of free fatty acids (palmitic acid for the most part) in the blood causes insulin resistance. Any erudite fat-lover will say to this, yes, of course it does. Palmitic acid is released into the bloodstream by the metabolic action of our own livers every time we fast (overnight, for example) or lose weight. It has to be. Otherwise we would never burn our fat stores, and we can't store much glycogen. The release of palmitic acid signals our body that we might not have a lot of food around, and we better preserve our precious glucose stores (the glycogen) for our brain to use. Therefore our muscles become more insulin resistant, and we shift to burning fat as fuel rather than glucose (burning fat sounds good, right?) This mechanism is physiologic, and I would say has very little to do with the full body insulin resistance of diabetes. Stephan and Peter have their own, brilliant takes on the matter (more required reading in my mind - no one said learning about nutrition didn't take a lot of time).

But let's get down to brass tacks on the insulin resistance/palmitic acid debate. Remember, and this is key, that when we burn fat and lose weight, we release a flood of palmitic acid into the blood stream. Deadly, hard core saturated animal fat. Yes, our own livers are trying to do us in. So why is fat loss, really, the best treatment for diabetes? Why does bariatric surgery, with the resultant forced semi-starvation, fasting, and FAT LOSS often result in the immediate turnaround of diabetes (4)? (Let's see - maximum of 2 pounds of fat loss a week = 7200 calories of fat burned, more or less, which would equal 1029 calories of fat a day = 114 grams of saturated fat (more or less) a day supplied by our own rumps! (or, hopefully, our visceral belly fat)).

This physiologic insulin resistance in fasting can, in the short term, increase fasting glucose levels in diabetics, it's true, and Gary Taubes' explanation of muscle insulin resistance vs overall body insulin resistance is a good one. This finding led the American Diabetic Association to recommend high carbohydrate diets to diabetics for years, and, in the long term, that is a huge mistake.

Did you know that feasting on your own stores of animal fat can help heart disease too (5)?

All right, I think I've fairly addressed the insulin resistance. Now let's go to the last, best argument against fat. Lipotoxicity. Perhaps I shouldn't have waited until the end for this one, as it is rather biochemistry-heavy. We'll give it a whirl. I have the full text for this paper (6), but let's summarize with the abstract:

"Insulin resistance is one of the pathophysiological features of obesity and type 2 diabetes. Recent findings have linked insulin resistance to chronic low-grade inflammation in white adipose tissue. Excess storage of saturated fat in white adipose tissue due to a modern life style causes hypertrophy and hyperplasia of adipocytes, which exhibit attenuated insulin signaling due to their production and release of saturated fatty acids. These adipocytes recruit macrophages to white adipose tissue and, together with them, initiate a proinflammatory response. Proinflammatory factors and saturated fatty acids secreted into the bloodstream from white adipose tissue impair insulin signaling in non-adipose tissues, which causes whole-body insulin resistance."

Let's leave off the insulin resistance for a bit and go to the proinflammatory section. Basically, what this paper says is that if we stuff our fat cells full of fat and then release saturated fat, we get inflammation. We hate inflammation here at Evolutionary Psychiatry, and this paper seems to implicate saturated fat as a major cause in a huge part of our bodies, the white adipose tissue (much of our stored body fat). This inflammation is called "lipotoxicity."

Paleo-diet aficionados tend to agree that doing the following are anti-inflammatory in the diet: omega-3 fatty acids (and avoiding omega 6), avoiding grains (especially wheat) and casein, eating vegetables and fruits, and avoiding sugar (fructose) and processed food.

Using common sense and biochemistry, saturated fat is anti-inflammatory compared to either cooked monounsaturated or polyunsaturated fat, given that heat and air can make the vulnerable unsaturated bonds oxidize and become rancid, which everyone can agree is highly inflammatory and bad for you. (Cold, fresh virgin-pressed olive oil would escape the oxidation, I hope!)

But here we have some science telling us saturated fat is inflammatory. And I don't think we have a full handle on that. I think what makes the most sense is to speculate that lots of saturated fat is inflammatory when combined with lots of sugar (big thanks to Dr. BG for helping me clarify this in my own mind! *edit* But I've further refined my thinking on this matter since publishing this post - please see the comments! Thank you *end edit*) Burning fat is a signal to our bodies that there might not be a lot of food around. Eating carbohydrates signals summertime! Lots of tubers and fruit and foliage! We stumbled upon a beehive! Yippie! Store it up! There was never a situation in our evolutionary past when we combined the grotesque amount of sugar we consume year round on the western diet, combined with the all the fats. Dr. BG called this, metabolically speaking, putting our foot on the brakes and the gas at the same time. Not great for the transmission.

I think, overall, the most important anthropological lessons are these - hunter-gatherers are healthy and, excepting infant mortality and accidents, long-lived eating a wide variety of macronutrient ratios. The Kitavans are high carb, the Inuit and Tokelau and Masai high fat. Most other folks were likely somewhere in between. But they did not consume tons of sugar. Or industrial seed oils, or wheat.

Again and again I come to that point. Epidemiology and observation won't show us the truth, but it will show us what could possibly be true, and what cannot. Saturated fat alone does not cause heart disease or diabetes. Neither do starchy carbohydrates alone. Those facts are true unless the Kitavans and the Inuit are blessed with magical pancreases or livers or hearts. My guess is they have the same old hearts you and I have.

Hopefully, science, a holistic approach, and sense will tell us the rest.

"Epidemiology is Bogus"

The paleoblogosphere is humming with excitement the past few days over the glorious work done by raw food blogger Denise Minger in her personal examination of the China Study, a large data set of epidemiology studies used by researcher T. Colin Campbell to formulate his book The China Study: The Most Comprehensive Study of Nutrition Ever Conducted and the Startling Implications for Diet, Weight Loss and Long-term Health. In it, Campbell comes to the conclusion that avoiding animal protein is the best way to avoid all sorts of diseases of civilization.

Denise's post uses the same China data set to implicate wheat as a major factor associated with heart disease and cancer, not animal protein. Kurt Harris of PaNu makes a point in his analysis of Denise's work that is the closest to my own struggles combing the literature - association studies are interesting, but troublesome. Conclusions from such studies should be viewed with a furrowed brow. "Hmmm, that's intriguing. I wonder why red-tailed baboons who eat less algae live longer than the red-tailed baboons who eat more algae? Why don't we do a prospective randomized controlled trial of red-tailed baboons and algae eating to sort that one out?" Because associations always come with confounding factors - turns out red-tailed baboons who eat algae love race car driving, and have you ever seen a baboon wearing a seat belt? Sophisticated statisticians will try to account for all these "confounding factors," but such a task can be simply impossible when examining a complex system such as society, or the biochemistry of the human body.

The psychiatric literature is loaded with brief, often useless, short-term randomized controlled studies of lesser and better quality and association studies. It seems the nutrition literature is even worse. Large, long prospective trials of good quality are horrendously expensive, and may take decades to do properly.

This is why I feel the healthiest and most sensible way to eat is based on an evolutionary paradigm, and that evolutionary-based lifestyle measures (though I haven't blogged too specifically about them yet, as the nutrition aspect is my primary personal interest, these measures would include regular exercise, meditation (as a proxy for the intense in-the-now concentration we used to use for hunting and gathering), proper sleep, working with the hands, and various other social/fun stress-reducing activities) are likely to be most effective for our modern, unsettled minds. It is not that there is a huge amount of science data backing that up - it is that until we have exhaustively proven otherwise (which so far, in my mind, we haven't), at least scientists can concede that our exceedingly complex human design is based on adaptations for our ancestors' lives.

For public health and sanity, I believe in an evolutionary viewpoint. And animal protein :)

Genes Are Not Destiny

We are the products of our mother's and father's genes (more Mom than Dad), but a modern understanding of genetics and biology shows us that how our genes are expressed are the product of our environment and what we do. How can that be, when we are allotted a certain genetic hand of cards at conception?

The science of epigenetics explains a lot (and leaves us with a lot of questions too). It turns out that genes can be silenced or turned on depending on how we live, and how we are treated. The body is not just a complicated jelly bag of enzymes and muscle and protein regulation; the very genetic material that directs all the regulation can change shape and redirect what goes on in the first place. So our genes regulate our proteins, but our proteins also regulate our genes.

Following the study of epigenetics, we also end up with the idea that what we do (and breathe and eat) affects our children and grandchildren, too. For example, in a small European community during World War II, babies were born smaller than usual. It makes sense. There was less to eat. But the children who were born smaller then grew up and had smaller babies themselves. Even more bizarre, epigenetic studies show that if your paternal grandfather had plenty to eat between the age of 9-12, your average lifespan is likely to be shorter than someone whose paternal grandfather didn't have enough to eat during that same critical age (1).

Why is this whole concept important to psychiatry? It's all about the brain. The brain has 100 billion neurons. 1.25 terrabyte memory capacity. 100,000 kilometers of connecting neuronal cables (2). Our human brains require many years of careful nuturing and protection as they reach maturity. The wiring process as we grow up depends upon a multitude of factors - nutrition, appropriate social attachment, education. Even after we are fully mature, the brain is still capable of change, or else we could never learn anything new.

Humans are all very closely related. There appears to have been a genetic bottleneck about 2000 generations ago, so that all of us are descended from a small family group that lived 50,000 years ago (3). Two randomly chosen humans have closer genetic similarities than two chimpanzees chosen from the same social group (2). There have been a number of changes over the last 2000 generations, but we are still so much more the same than different. The contention that "all men are created equal" has more scientific truth to it than one might think.

Let's pull all these separate threads together - we are born with a certain genetic hand. We can alter that hand for ourselves, our children and grandchildren by how we live. The brain is the most complicated organ in existence, and the interplay between our genes and how we live will affect the brain in countless ways. Finally, we are all brothers and sisters, and, with few exceptions, have enormous genetic potential for success.

Hardly any of us are doomed by our genes to be obese, diabetic, or depressed. There are simply too many other factors at play to make that flat statement. Yes, if your parents are obese, and you eat and do the same things your parents do, you are more likely to be obese yourself. The logic follows that if we eat and do similar things to what our lean ancestors did, we will be lean. We can't just wait for a new diet pill, a new surgery, a new exercise contraption to solve our problems for us. There are too many factors at play.

With the brain, the factors expand a thousand fold. Lifestyle, nutrition, and proper nurturing are more important for the brain than for any other organ. Hopefully, now, we can finally use medical science to address the whole picture, instead of looking for a single magical chemical or pill. We're all meant to be strong, smart homo sapiens - and we can be, if we work at it. And if genes are our destiny, then we are meant to be that small, intrepid band of humans who conquered the world, for good or ill.