The Evidence the «Saturated Fat is Harmless» Crowd Overlooks

cheeseI’ve talked a lot about saturated fat here on the site. That’s not by coincidence. I’m very concerned about the fact that the notion that saturated fat is harmless has gained foothold within the nutritional community. More and more people seem to be adopting the mindset that it’s perfectly safe to consume large quantities of saturated lipids. I find this very concerning, seeing as a large body of evidence refutes that idea. As I pointed out in my recent article entitled Saturated Fat: It’s (Still) Not Harmless, I think it would be a fatal mistake to tell the public that it’s unproblematic to consume a lot of butter, fatty meats, cream, and other foods that are very high in saturated fat.

It’s time for a reality check

In my previous articles on this topic I’ve presented strong evidence showing that it wasn’t until very recently – on an evolutionary timescale – that large quantities of saturated fat were infused into the human diet. None of the foods that were available to our preagricultural forebears contained anywhere near as much saturated fat as butter, GHEE, cream, and other similar high-fat foods do. Game meat is very lean compared to domesticated meat. Moreover, it generally contains a lot more omega-3 and a lot less saturated fat. Our primal forebears obviously did take in some saturated fatty acids; however, they didn’t take in anywhere near as much saturated fats as the average Atkins dieter. This goes without saying, seeing as fatty domesticated meats, coconut oil, and dairy foods were not a part of their diet.

These facts alone should make us think twice before we incorporate foods that contain very high concentrations of saturated fat into our diets.

The evolutionary heath model predicts that the consumption of a diet that differs markedly from the diets that nourished our preagricultural ancestors will adversely affect one’s health. The science that underlies this prediction is solid. The evolutionary health model is not built on a bunch of observational studies or anecdotal reports; rather, it’s foundation is composed of well-established principles of evolutionary science, as well as experimental and anthropological research.

Given that it’s only very recently that butter, ghee, and other foods that contain extremely high concentrations of saturated fats became a part of the human diet, it’s not surprising that a high intake of these types of foods has been shown to be detrimental to health. One particularly important line of evidence that the people who make the case that saturated fat is harmless seem to overlook is the one that consists of evidence derived from studies that have looked into the link between saturated fat consumption and microbiota composition/inflammation.

Many saturated fat lovers seem to be unaware of the fact that a long list of studies has found that many types of saturated fats possess proinflammatory properties (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11). The consumption of large quantities of saturated fat leads to immune activation and shifts in the configuration of the gut microbiota that are unfavorable from the perspective of the human host (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11). It’s not just one or a couple of studies that have found this to be the case. A lot of studies have. Some of the studies are indeed in vitro or animal studies; however, research in humans has also been conducted.

If the results from the research in this area had been all over the place, I wouldn’t have put much weight on them. That’s not the case though. Pretty much all of the studies in this area point in the same direction. The weight of the evidence clearly indicatea that it’s problematic to consume a lot of saturated fat. I would say that the evidence is convincing.

Here’s what a 2010 study had to say about the role saturated fats play in inflammation and endotoxemia:

Concentrations of SFA [Saturated Fatty Acids] and LPS [Lipopolysaccharide] that are commonly present in conditions resulting from excess nutrition (eg, obesity, insulin resistance, type 2 diabetes, etc) and high-fat diets can lead to inflammation that is several-fold greater than the direct proinflammatory effects of each of these factors alone. The elevation of SFA and LPS in these settings could create a “perfect storm” of factors leading to greatly increased monocyte/macrophage innate immune responses. Because monocytes/macrophages are critical cells mediating tissue and systemic inflammation, a broad and “synergistic” amplification of their inflammatory activity by SFA may be an important contributor to the genesis or progression of insulin resistance and type 2 diabetes, as well as the cardiovascular sequelae of these conditions. (10)

Most of the people who make the case that saturated fat is benign probably don’t deliberately overlook this evidence; rather, they have likely never seen it. This is one of the reasons why I think it’s important that it gets more widespread attention.

Why does the consumption of large quantities of saturated fat negatively affect immunity and gastrointestinal microbiota composition?

The natural question that follows from the previous section is: Why does a high intake of saturated fat cause inflammation? Many theories have been proposed. Personally, I always bring out an evolutionary toolkit when I am to answer questions such as that one.

When we think about it, it’s not really surprising that a diet rich in saturated fat doesn’t agree with our bodies, seeing as it wasn’t until very recently that we humans took up dairying and started eating meats derived from sick, fat animals. From the perspective of the human genome, a diet that is rich in fatty meats, butter, cream, and other similar foods is a foreign diet.

Our microbiotas are a part of our milieu. It’s not just changes in the visible part of our environment that can produce genome-environment mismatches; changes in the invisible part can as well. The type of microbiota that is produced by diets that differ substantially from the type of diet our ancestors consumed for millions of years prior to the Agricultural Revolution does not match well with the biological system that is the human body.

If saturated fats had been a major part of our Paleolithic ancestors’ diets, we would undoubtedly have been better adapted to eat foods rich in saturated fat and harbor the type of microbiota that results from a high intake of those foods. We don’t need a study to know that, all we need is a basic understanding of evolutionary science.

If our primal ancestors had consumed a diet rich in saturated fat, natural selection would have favored those ancestors of ours who possessed heritable traits that allowed them to consume such a diet without suffering fitness wise. Many of the problems (e.g., fatigue, impaired sexual function) that arise as a result of chronic immune activation and inflammation compromise organismal fitness; hence, it’s safe to assume that saturated fat wouldn’t have been as inflammatory as it is if it had made up a large part of our primal forebears’ diet.

Recent studies have shown that polyunsaturated fatty acids (in particular omega-3 fatty acids) and monounsaturated fatty acids are capable of blocking the growth of many human pathogens (3). Saturated fats are much less potent with respects to their antimicrobial effects. Not only that, but they may actually act as a growth substrate for certain proinflammatory gut bugs (3). This is likely one of the reasons why the consumption of saturated fat has been linked with dysbiosis, endotoxemia, and chronic inflammation.

It’s important to point out that long-chain saturated fatty acids are a lot more problematic in this respect than short chain fatty acids (12 carbon atoms or less). The short-chain fatty acids that are produced in the colon following the fermentation of dietary fiber are generally not inflammation-inducing. On the contrary, they have potent anti-inflammatory effects (3, 12). Furthermore, lauric acid (C12), the primary fatty acid found in cocunuts, possesses potent antimicrobial properties (3), and exerts different effects on blood lipid parameters than longer chain fatty acids (13). The evidence I’ve seen suggests that it’s pretty harmless.

This can help explain why traditional people such as the Kitavans are so healthy “despite” the fact that they eat a lot of coconut. With that said, I would argue that it’s unwise to take in a lot of coconut oil, coconut butter, and other similar products on a daily basis. Not just because those types of foods are very calorically dense, but also because lauric acid probably only made up a minor part of our Paleolithic ancestors’ diet. A very high intake of this nutrient may cause gut disturbances.

I would argue that most people would benefit from taking in less, not more, saturated fat

There’s still some things we don’t know about the mechanisms that connect saturated fats with inflammation and endotoxemia. What we do know, however, is that saturated fat isn’t harmless. The consumption of saturated fat has been firmly linked with several adverse health outcomes. A lot of the people who argue that it’s perfectly safe to consume a lot of butter and bacon seem to focus all of their attention on the clinical trials that have looked into the connection between saturated fat intake and various health outcomes, overlooking everything else. In my opinion, that’s a big mistake.

As I’ve pointed out many times on the site in the past (e.g., this one), it’s not surprising that the randomized, experimental studies in this area show conflicting results, seeing as it can be very difficult to adequately assess single nutrient-health relationships in clinical trials.

Before we wrap up, I would like to repeat what I’ve said in my previous articles on this topic: There’s no reason to shun all foods that contain saturated fats. The world isn’t separated into good and bad things. Eggs, grass-fed meats, and several other healthy foods contain small-moderate quantities of saturated fat. We shouldn’t avoid these foods just because they contain some myristic acid and other saturated lipids. What I would argue though, is that we would be wise to severely limit our consumption of calorie-dense foods that contain very high concentrations of saturated fat, such as butter, ghee, cheese, cream, and fatty, domesticated meats.

Not everyone who’s actively fighting to defend the honor of saturated fat claim that their beloved nutrient is completely harmless. Some have realised that it’s not. Not everyone though. Hopefully this article can help get more people to realise that saturated fat is not harmless; a realisation that could translate into positive health outcomes.

Picture: Creative commons picture by Jonathan Steffens. Some rights reserved.


  1. Guilty as charged! I was certainly on the HFLC bandwagon… it wasn’t a meal unless it had butter, coconut oil, bacon, cream, avocado and eggs on it! And then it all went wrong for me… related to my current food intolerances and allergic reactions? It’s hard to say. But I’ve read somewhere that high fat diets increase the mucosal munching bacteria, so they chow down on the mucus, leaving you exposed with gaps that go on to form leaky gut… It makes sense if it’s true. Not only that but I think fat really doesn’t contain many nutrients… so you’re eating all that, for what nutritional benefit? I went a bit nuts on all that fat for a while… it tasted bloody great… But that could be one of the reasons why I’m suffering now. Who knows.

  2. Bone marrow is high in saturated fat and is attributed as the reason that we have big brains.

    • Hi Mark,

      Most of the fats in bone marrow are of the monounsaturated kind (1, 2, 3).

      The fatty acid composition of “modern” high-fat foods such as butter, fatty domesticated meats, and ghee differs markedly from that of the animal source foods that were a part of preagricultural human diets. The most important difference is probably that the former contain more saturated fats and less polyunsaturated omega-3 fatty acids than the latter (as measured in % of total fat).

  3. Geri Puritch says:

    Well done. Thanks for the clarification and also the supporting evidence. I have been asked by my doctor to reduce my cholesterol and I know it was diet induced. I’m continuing with the Paleo diet with reduced fat now and I am feeling better but still have a ways to go. My sleep still seems to be quite disturbed and I’m working on illuminating caffeine for my diet.
    Keep up the good fight.

    • Hi Geri,

      I’m glad you liked the article.

      Note: You don’t have to worry about “overconsuming” saturated fats if you’re eating a Paleo-style diet, seeing as none of the foods that are a part of the Paleo diet contain large quantities of saturated fats. Coconuts are quite high in saturated fat, but they primarily contain lauric acid, which, as I point out in the article, has some unique properties that separate it from longer chain saturated fatty acids. Olives, avocados, etc. contain primarily monunsaturated fats, not saturated ones.

  4. The crowd you’re talking about consists of the same people who think “If a little is good, a lot has to be better.” They are the ones who hop on every dietary bandwagon and go totally overboard with it–until they realize it isn’t working for them.

    I read comments from people on various websites who claim that they aren’t losing weight on a strict Paleo diet. Then, when I read a little farther, I find out they are literally stuffing themselves with various types of fats, which will definitely inhibit weight loss. (The idea that fat won’t make you fat is nonsense. It will if you eat enough of it.) I think moderation in everything (except maybe fresh, low-glycemic vegetables) is the key.

    I happen to prefer fatty meats because they taste so much better to me. But I don’t overdo other fats. I stick with a fairly Paleo diet and don’t consume much dairy. I do like eggs but don’t eat them every day. Same with avocados, olives, etc. Again, I think it’s all about moderation and a lot of variety, at least for me personally.

  5. Actually, I take issue with your whole Darwinian argument against saturated fat consumption as well as the oversimplified discourse on this broad spectrum of lipids. In part, I think a large part of your biased is shaped by a current modern view of how meat and fat is consumed today.

    So going back in time, pretty much all paleoanthropologists agree that homo sapiens ancestors were initially scavengers, and probably remained scavengers for a fairly long time. So did these scavenger eat lean muscle meats from leaner animals like deer or pronghorn? No they ate the remains that the primary predators left behind and this included the portions of animals that the predators couldn’t consume without tools. How do we know this? Tool marks left on bones go back approximately 2.6 million years. What type of bones were broken? Larger femurs and skulls. So what kind of meat would have been the most readily available for mankind’s early ancestors? Bone marrow and brains. And what do these sources of “meat” have in common? They are high in saturated fat!

    The amount of saturated fat in bone marrow varied from animal to animal, and time of year depending upon what that specific animal ate. So for example the amount of stearic acid in caribou bone marrow could be as high as 21 percent to as low as 6 percent, and palmtic acid as high as 26 percent and as low as 13 percent in the same tissue (see ).

    Note too that very few fats from meat in nature are ever any one type of fat. (bone marrow is high in different kinds of monounsaturated and saturated fats). They are a mixture of different types of saturated, monounsaturated, and polyunsaturated fatty acids. These mixtures vary in different types of animals at different times of the years as well as vary in different tissues of the same animals. These mixtures vary considerably based upon what animals eat. Here’s a good study on this topic- Not all saturated fats are equal. Some saturated fats appear to be protective, while other when out of balance appear to be detrimental. So broad categorization of saturated fats as “good” or “bad” is a pretty dumb exercise. I highly recommend picking up a copy of “Know Your Fats” by the late great lipidologist Mary Enig

    Anyway, back on the evolutionary chain, as mankind moved into more severe climates, when exactly would mankind be most in need of meat to sustain him or her selves? In the spring and summer when their were other sources of food including plants and insects (more about insects later)? Nope…instead in the winter when those plants and insects weren’t available. Now what do animals do to survive during the times of the year when plants are also unavailable for them? They put on FAT! So when did an evolving mankind need to eat the most meat? Not when animals were their leanest, but when animals were at their fattest points. Plus mankind also often preferred to eat the fattier animals, not the leaner ones people hunt nowadays. In Europe stepped bison, bison and auroch were consumed to extinction (stepped bison and auroch) or near extinction (bison). In North America, much more recently bison were the preferred food on the plains, pronghorn were and deer weren’t. Bison store a lot of fat. Going further back in time,wooley mammoths, and mastodon all had fattier meats, large brains and a lot of fats concentrated around organs.

    But these weren’t the only sources of fat. Unlike today, where dams and pollution have decimated wild salmon populations, rivers use to be so thick with salmon up and downs the coasts of countries that even recent records from the 1880’s in North America record salmon as far as the eye can see. So needless to say this source of atty fish was much more plentiful as were other forms of fatty fish.

    Now as for insects, during the course of hominid and human evolution there weren’t the taboos about eating these creatures that exist in current Western culture. (As an aside, many non-western cultures still eat a lot of insects). Nope our ancestors ate them for millions of years. People often cite what a great source of protein insects are, but they also forget what a good source of fats insects are as well. Fatty acids are required for all kinds of insect functions like the of biosynthesis pheromones and waxes. And guess what? These fats are various profiles of fatty acids including long chain saturated fats like stearic, palmitic and myristic fatty acids. Click here to read more about the fatty acid compositons of insects. You can download the full text from this link.

    So in short, while your argument has some merit in the current context, in my opinion your evolutionary argument is biased by a framework shaped by a modern view of our sources today of saturated fats. While it’s true homo sapiens and our hominid ancestors didn’t get our saturated from dairy products like milk, cheese and butter, we did get a lot of saturated fats from other sources not as widely consumed today especially in western societies. Now what would be a more interesting and meaningful discussion, from an evolutionary point of view, would be a look at the shift of the types and concentrations of saturated fatty acids moving from brains, marrow, fatty fish and insect sources of saturated fatty acids to dairy sources of fatty acids. Well, at least, to me that would be more interesting and meaningful.

    • So are you mainly eating brains and bone marrow? @LAchefs

      We’re so far removed from our ancestors diets, that we don’t know who ate what most of the time! How do you know for a fact that this was their mainstay… or do we just know they did eat some, based on fossil records, but with no clue as to their frequency? A supplement to the other thousands of species of plant, herb, starch, fungi, fruit and whatever else that they hunted, gathered or found on a daily basis. It’s not the same as bacon cooked in lard, and coffee mixed with butter. I think the good fat, bad fat argument has already been explained, and what we need to know now is how much fat? Cause there’s very little nutritional benefit to high fat from what I can see… And it seems to do the microbiome no good at all! How is that a good thing? Maybe a little goes quite a long way… and like most things, more does not make it better?

    • HI LA Chefs,

      You bring up many important points.

      Much of what you say is in line with the statements I’ve made here on the blog. With that said, I do think you miss the main point I’m trying to make with the article. I’ve never claimed that our Paleolithic ancestors didn’t consume brain, marrow, and other fatty animal source foods. Moreover, I recognize that some saturated fats are a lot less problematic than others. For example, lauric acid (C12) has some unique properties that separate it from longer chain saturated fatty acids. Also, perhaps needless to say, I know that meats contain mixtures of saturated-, monounsaturated-, and polyunsaturated- fats; they don’t just contain one type.

      This leads us over to the key points I’m trying to get across with my articles on saturated fat, which are:
      – The fatty acid composition of domesticated, fatty meats differs markedly from that of meat derived from wild animals. Wild meat, including marrow and brain, typically contain more monunsaturated and polyunsaturated omega-3 fatty acids and less saturated fatty acids than domesticated meat. Domesticated animals are also a lot fatter than wild animals.

      – The fatty acid profile of high-fat dairy foods such as butter and ghee differs markedly from that of the animal source foods that supported the evolution of the complex human brain and body. High-fat dairy foods are exceptionally high in saturated fat. Whereas the most dominant type of fat in fatty animal foods such as marrow is monunsaturated fat, the dominant one in high-fat dairy foods is saturated fat.

      – The fatty acid composition of a contemporary low-carb diet that contains moderate-large amounts of butter, ghee, coconut oil, cheese, domesticated fatty meats, etc. differs markedly from that of the diets that conditioned the human genetic make-up over millions of years.

      – Very few of the foods that were on our Paleolithic ancestors’ menu were very calorically dense and high in fat. Obviously, our primal forebears didn’t have access to unlimited amounts of bone marrow. Today, however, the situation is very different. Many low-carb dieters eat a great variety of calorie-dense foods, many of which contain extremely high concentrations of saturated fat.

      – It’s probably much less problematic to consume saturated fat in the form of foods that are high in monunsaturated fats and/or polyunsaturated omega-3 fats as opposed to in the form of foods that are very high in saturated fat and low in monunsaturated fats and polyunsaturated omega-3 fats. To illustrate this, imagine that a person eats a meal that is high in butter and bacon, and hence, high in saturated fat. Such a meal is likely going to negatively affect that person’s gut microbiota and raise the levels of LPS in his system. However, if he eats bone marrow or brain derived from a wild animal, his body will likely respond in a very different manner. This time, he’s taking in a lot of monunsaturated fatty acids, as well as polyunsaturated omega-3 fats. He’s also taking in modest amounts of saturated fat; however, that’s unlikely to be problematic in the presence of the former fats, seeing as they possess anti-inflammatory and antimicrobial (they hinder the growth of some human pathogens) properties.

      – The notion that it’s unwise to consume a lot of saturated fat is supported by a large body of evidence, as I’ve shown in my articles on this topic

      The bottom line: As long as we avoid foods we’re not well adapted to eat, then we’re on safe ground. Paleo dieters don’t need to think much about the above things, seeing as the Paleolithic diet matches well with the human genetic make-up.

      Thanks for your comment.

      • Since you mentioned bacon, I take it you don’t know anyone who raises heritage breeds of pigs, especially the breeds that are more recently descended from wild boars like Mangalitsa and Ossabaw pigs. If you did, you’d realize a few things. First wild pigs are naturally very fatty, since lacking sweat glands, they use fat to regulate their body temperature. Industrial pigs are actually a lot leaner. So this doesn’t support your whole eating more fatty animal theory you promulgated above. Second, many pigs were as much a source of fat as they were of meat. There was no shipping of olive oil all over the world. Third, the composition of a pig’s fat is directly related to what they’re fed or forage. For example my friend who finishes his Mangalitsa and Mangalitsa crosses in the woods on feed and forage (including bark and acorns) has had the fats tested from his pigs. His lard is nearly 60% oleic acid, a monounsaturated fat which is the same MUFA as is in olive oil. Real olive oil is 70% oleic acid. In total the lard from my friend’s pigs is over 70% MUFA’s & PUFU’s. Most pastured pigs are also primarily MUFU’s & PUFU’s around 55 to 60%. Whereas lard from industrial pigs is more closely 50 to 55% SFA’s.

        In general, most livestock was raised for both meat AND fat. (Fish were another source of oil- herring oil, cod liver oil, etc) And when pastured based, the tallow and suet from beef and lamb for example still contained around 40% oleic acid. The fatty acid profiles of these pastured animals (including Omega 6 to 3 ratios ) vary quite a bit from feedlot grain finished ruminants. Butter and milk fat from pastured animals eating grasses also has a very different fatty acid profile (plus much higher in vitamin K2) from that of dairy animals fed soy meal and corn starches in dairy CAFO’s. Pastured animals have fatty acids profiles more similar to wild animals. Plus the composition of those profiles and the amount of fat vary upon the time of year when the animals are slaughtered. This is a lot different than industrialized product that has very to little, if any, seasonal variability.

        So maybe your real, or bigger, argument is with industrialized production of the sources of saturated fats in modern diets which reduce the amounts of MUFU’s. Though honestly, the bigger issue, in my opinion, is that fats from pastured animals have been largely replaced in cooking (especially frying) with easily oxidizable highly processed/industrialized PUFU’s like corn, soy and canola oil that were never ever part of our evolutionary diets in any form or fashion. Higher percent saturated fat like those from coconut and palm oil has also replaced the mixed fats from pastured animals. Most Westerners have not evolved eating these types of tropical fats.

        • Great discourse here (going to follow along). This is an area I have been researching quite a bit as well and tend towards the safe saturated fat side. I agree largely with the concern in replacing stable saturated fats with unstable easily oxidized PUFA (albeit cooking in fats isn’t entirely a paleolithic practice, as far as I’m aware…).

  6. Hi Erik, I havent had time to read through all the studies, but from a vast majority of the ones I have read in the past, they have shown inflammation and endotoxemia when combined with carbohydrate in the diet, but this doesnt occur without the combination of carbohydrate and saturated fat. Can you confirm?

    • Hi Richard,

      Actually, a high intake of saturated fat, by itself (i.e., no carbohydrate), is problematic. I suggest you check out the studies I link to 🙂

      Again, I’d like to point out that saturated fat is a natural part of healthy whole foods such as grass-fed meat and eggs. One shouldn’t avoid these foods simply because they contain saturated fat. The message I’m trying to get across is that many of the foods that we – contemporary humans – have access to contain, from an evolutionary perspective, supranormal concentrations of saturated fat. Examples of such foods are ghee, butter, cream, and processed, fatty meats. A diet that is high in these types of foods bears little resemblance to the type of diet that we’re genetically best adapted to eat.

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