I’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.