by Bret Contreras March 24, 2014
Official health authorities have for decades claimed that a high saturated fat intake is linked to heart disease, stroke, cardiovascular disease, and surges in blood cholesterol levels, and even those people who pay little attention to nutrition have therefore usually learned sometime during their life that butter and fatty meats are something that should be avoided if you want to live a long and healthy life. However, since the advice to reduce fat intake was first included in the official dietary guidelines in the U.S. and other industrialized countries, some experts have argued that there really isn’t enough evidence in support of the diet-heart hypothesis – which states that an imbalance of dietary cholesterol and fats, and high serum cholesterol, are the primary causes of atherosclerosis and cardiovascular disease. In the last couple of years, more and more studies have indicated that the villification of saturated fat is unfounded, and many paleo (+dairy) and low-carb dieters have therefore completely dismissed the conventional wisdom and started consuming plenty of coconut oil, bacon, cheese, cream, and GHEE. But where does the answer lie? Should we trust the official dietary recommendations, or should we abandon the the notion that saturated fats are bad for you?
When we’re faced with a hypothesis or dilemma related to nutrition and health it’s always wise to start by looking at the millions of years of human evolution. While we can rarely draw any causative conclusions by looking at ancestral diets and epidemiological studies, an evolutionary perspective on human health provides the framework for good nutrition in the 21st century. This is where a lot of dietary advice seems to fail. If we’re not starting with the right foundation, modern science can seem like an impossible maze with reviews and studies showing all sorts of different results.
While we don’t have to emulate the diet of our hunter-gatherer ancestors to be healthy, we can learn a lot by simply looking at the way humans have eaten since Homo sapiens first started killing animals and eating wild plants in Africa. Although we can’t define the optimal human diet by simply looking at the nutritional template of our ancestors, the fact that humans can be lean and healthy on diets with widely different macronutrient compositions suggests that neither a high intake of carbohydrate nor fat is necessarily problematic. Since we also know that meat has been an important part of the human diet for hundreds of thousands of years, we can quickly dismiss the notion that humans suddenly aren’t adapted to eat animal source foods – as claimed by some proponents of vegan diets.
In 1989, the swedish researcher Staffan Lindeberg and his colleagues set out to document the health of non-westernized people, and on the Island of Kitava in Papua New Guinea they found one of the last populations on earth still eating a diet that resembled that of our paleolithic ancestors (1). The kitavans eat a high-carbohydrate ancestral diet primarily composed of root tubers, fruits, vegetables, fish, and coconuts, making up an average macronutrient intake of 69% carbohydrate, 21% fat, and 10% protein. Since the Kitavans eat plenty of coconuts, the majority of fats in their diet are saturated.
Despite a macronutrient composition that is fairly similar to that of the “western diet” – with a slightly higher carbohydrate intake relatively to protein and fat – the kitavans are all lean and healthy, with no indications of stroke, diabetes, dementia, cardiovascular disease, or congestive heart failure. Lindeberg and colleagues published a series of reports from the Kitava study that tell us one especially important thing: Simply looking at the intake of fat-, carbohydrate- and protein- doesn’t really tell us that much about the healthfulness of the diet.
While most of the fatty acids in the diet of the kitavans are saturated, the total fat intake isn’t that high. Is it possible that their relatively low total fat intake could help explain why they didn’t experience any of the health problems often associated with a high intake of saturated fat? Not likely. Other non-westernized populations living in hot climates have also maintained excellent health while relying on coconut fat as one of their main sources of energy. One example of this is the tokelauans living in New Zealand, whose traditional diet contained between 54-62% energy from coconut. Despite this extremely high fat intake, these islanders had very low rates of heart disease, obesity, and other diseases of civilization as long as they were unaffected by western lifestyle (2).
Bottom line: The high intake of coconut in these non-westernized populations shows us that it’s possible to be healthy while relying on saturated fat as a main source of energy. Since coconut is a whole, unprocessed food that has been an important part of the diet of many healthy human populations, I find it insane that some people suddenly claim that eating coconut meat is bad for your health.
While the study of healthy populations relying on coconut as an important source of energy provides a good starting place for looking at the connection between saturated fat and human health, it doesn’t tell us that much. We know that not all saturated fat is the same. While coconuts primarily contain lauric acid, the primary saturated fat in the western diet is palmitic acid. Palmitic acid is commonly found in dairy products and meats, both of which are common staple foods in many affluent nations. Is it possible to be healthy while eating a diet rich in saturated fat from meat and dairy?
To investigate this question, let’s turn our attention to the african savanna. The traditional diet of The Maasai, a pastoralist tribe living in Kenya and Northern Tanzania, is exclusively composed of milk, blood, and dairy, and estimates show that men in this semi-nomadic tribe get about 33% of their daily energy from saturated fat (3). The Maasai have one of the highest intakes of cholesterol and saturated fat from animal source foods ever documented and therefore serve as a good test for the hypothesis that a diet high in saturated fat and colesterol increases the risk of chronic disease! If myristic-, palmitic- and stearic acid are as bad as some health authorities claim, the Maasai should be dying left and right from heart attacks and atherosclerosis. However, this is not what we’re seeing. Studies actually suggest the opposite, The Maasai are lean and healthy as long as they stick to their traditional diet (4,5,6). Other studies of non-westernized tribal societies eating meat-heavy diets, such as the Kavirondo- and Turkana people in Kenya, have also come to the same conclusions (7).
Bottom line: It’s possible to maintain good health while eating a lot of saturated fat from meat and dairy.
While looking at the diet of healthy traditional populations that lived or still live around the world doesn’t really provide any definite conclusions about the best way to eat, it does provide a powerful framework in the sense that we can quickly exclude certain hypothesis and ideas. This helps us tremendously in the search for the “optimal” human diet in the 21st century since we can focus our efforts on the right types of questions and science. We’re not spending time on ideas that have no evolutionary support.
Since several non-westernized people are lean and healthy while eating plenty of coconut, fatty meats, and/or dairy, we can already conclude that saturated fat isn’t the evil and artery clogging nutrient some people claim it is. However, the good health of tribal societies eating meat-heavy diets doesn’t imply that everyone should eat a high-fat diet. The sources and quality of the food definitely matters, and in the context of the western diet and lifestyle, a high saturated fat intake could have very different effects. Also, while the semi-nomadic people in Kenya clearly are fit and healthy, we can’t exclude the possibility that they would be even fitter if they replaced some of their meat and cow’s milk with fruits, vegetables, and nuts.
So, knowledge about these traditional populations provides a good framework, but to really be able to say anything concise about the effects of saturated fat on inflammation, heart disease, and stroke, we have to look at modern science. For years we’ve been fed the idea that saturated fat increases blood cholesterol and disease risk, and some researchers don’t even bother to cite studies when talking about the dangers of a high-fat diet. The idea that saturated fat is bad for you has gained such a strong foothold among the general public that the majority of people without any experience in nutrition take it for granted that low-fat products are superior to full-fat. And while a large majority of dietitians and nutritionists who’ve bothered to keep up with the latest research have realised that the connection between saturated fat and disease is not as cut as dry as some of their former professors were claiming, the official dietary guidelines in most countries still propose that everyone should reduce their intake of fats – and especially the ones that are saturated. But what does the science really tell us? Should we throw out coconut, red meat, and other high-fat foods that have been a part of the human diet for hundreds of thousands of years?
When dealing with nutritional science we usually have to combine results from several different sources to be able to draw accurate conclusions. Meta-analysis and systematic reviews are great to have in that regard since they combine findings from several independent studies. It’s easy to find a single study supporting your ideas, but if we look a little deeper we quickly learn that confounding variables and shortcomings in the study design could be the reason we’re getting the results we’re seeing. This is the reason science can be so confusing. Proponents of low-carb diets have a different perspective on the available data than health authorities advising people to reduce their fat consumption, and we therefore end up with dietary advice spread all over the place.
However, with a sound evolutionary backbone and reviews of the most recent science we’re on safe grounds. Let’s first take a look at the recent research that has emerged during the last couple of years, which doesn’t find any association between saturated fat consumption and chronic disease.
Bottom line: Recent systematic reviews don’t support the notion that a higher saturated fat intake is associated with increased incidence of cardiovascular disease or heart disease. Some reports even suggest that a high saturated fat intake helps protect against certain types of chronic health disorders. However, the picture is never this cut and dry. A high-fat diet can potentially increase low-grade chronic inflammation (more on this next), which could help explain why the diet-heart hypothesis never has been completely dismissed.
It’s important to remember that several lifestyle factors, such as sun exposure, physical activity, and exposure to microorganisms, can help explain the excellent health of non-westernized populations eating high-fat diets, and we therefore can’t exclude the possibility that some aspects of their “ancestral” lifestyle protect them from the proposed harmful effects of saturated fats. It’s also important to remember that we have to look at the overall quality of the diet, not just a single component.
Are the meats you’re eating as healthy as those consumed by non-westernized people in Kenya? Probably not. Meat from grain-fed animals typically contain a higher total amount of fat than wild and pasture-fed meats, and a higher concentration of saturated fats (17). And it isn’t just a small difference, grain-fed animals contain 2-3 times more saturated fats than game meat and less of the essential omega-3 fatty acids. Also, the Maasai-, Kavirondo- and Turkana people in Kenya clearly aren’t getting trace-residues of antibiotics and growth hormones in their meats!
We’re often told to eat more fish and reduce the consumption of red meat, but what is becoming increasingly clear is that red meat in itself isn’t the problem, but rather the way it’s produced and processed. Processed meat from grain-fed animals pumped full of antibiotics and growth hormones clearly isn’t the same as a nice, juicy steak from a grass-fed or wild animal.
Dairy products obtained from wild and domesticated ruminants also have different fatty acid compositions, and some people have raised concerns saying that pasteurization and homogenization can force milk casein and fats into new configurations (18). While the possible downsides of milk processing techniques haven’t been fully investigated, it’s clear that the fat-reduced, pasteurized, and homogenized milk found at the average grocery store is a far cry from the nutrient-packed, live milk consumed by healthy traditional populations such as the Maasai.
We also can’t exclude the idea that these traditional cultures have developed certain genetic traits that increase their protection against hypercholesterolemia and heart disease. However, the fact that these cultures are healthy on diets with a high saturated fat content suggests that saturated fat in itself isn’t necessarily the problem.
Bottom line: Overall diet quality, lifestyle, and genetics could help explain why non-westernized people are healthy while eating a high-fat diet, and we therefore can’t exclude the idea that a high saturated fat consumption could have a different effect in the context of the western diet and lifestyle.
Even if we don’t include the obvious offenders, such as potato chips and deep fried burgers, there’s still an apparent mismatch between the most common sources of saturated fat in the typical western diet and the sources of saturated fat in the diet of our paleolithic ancestors or that of healthy non-westernized cultures eating meat, dairy, and coconuts.
Although butter, GHEE, cream, and other high-fat dairy products have been an important part of the diet of many healthy and long-lived populations, these foods contain a saturated fat concentration that is higher than anything humans have been eating throughout most of our evolution. But does this really matter? It might. Some of the richest sources of fat in the diet of our paleolithic hunter-gatherer ancestors were organ meats and coconuts, and while these products contain a relatively high amount of saturated fat compared to most other foods, they are lightweighters in comparison to GHEE, butter, and other products introduced after the agricultural revolution.
Since humans first started domesticating plants and animals about 10,000 years ago, advancements in processing techniques have allowed us to create new products with a macronutrient composition that isn’t found in nature. This has been especially apparent during the last couple of centuries, where products with a very high concentration of either carbohydrate or fat, such as refined grain products and vegetable oils, have become important staple foods all over the world. While the unprocessed foods available in the wild contain a balanced proportion of macronutrients and micronutrients, a lot of the products consumed in the modern world have an unnatural nutrient composition.
One problem with these highly concentrated sources of fat, such as GHEE, cream, and vegetable oils, is that they are less satiating per calorie compared to organ meats, whole coconuts, nuts, and other completely unprocessed foods (16). In general, products with a high-energy density (calories per gram of food) are less filling than foods with a low energy density, which typically contain more water, fiber, vitamins, and minerals. Just imagine how much easier it is to get 300 kcal from butter (∼717 kcal/100g) than potatoes (∼77 kcal/100g), or how 300 kcal from raw coconut meat fills you up with fiber, fat, and some protein and water, while 300 kcal from coconut oil doesn’t have the same effect. While this clearly isn’t a problem for a 240 pound muscular guy who’s striving to get enough energy into his body, it can be an issue for someone who’s struggling to lose weight.
Besides the inferior satiety index, these high fat foods could also contribute to the low-grade inflammation often seen after a high fat meal, by rapidly increasing the production of chylomicrons that bind bacterial endotoxins and/or by promoting an environment where bad bacteria are able to thrive in the upper intestine.
While this doesn’t mean that high-fat dairy products and extra virgin coconut oil are bad for you, it suggests that it’s easy to overconsume these foods. Since most people aren’t going to eat coconut oil, butter, or GHEE on their own, these foods are usually combined with other foodstuffs high in carbohydrate and/or protein, making up a fairly palatable product.
Bottom line: Oils and some high-fat dairy products contain a very high concentration of saturated fat and are less satiating per calorie compared to coconut meat, organ meats, and other completely unprocessed sources of fat. Dense sources of fat are often combined with other rewarding nutrients, making up a highly palatable product that potentially overwhelms the reward center in the brain. The increased concentration of fatty acids in the small intestine during the digestion of high-fat products could have an inflammatory effect.
But what are really the causes of heart disease, cardiovascular disease, and other disorders that saturated fat has been blamed to increase the rates of? While we know that chronic diseases are multifactorial, we also know that there are a couple of things that seem to be especially important in the epidemic of non-communicable disorders now seen in the industrialized world. One of these essential components is low-grade chronic inflammation. Contrary to the acute inflammation that occurs when you sprain your ankle or get a wound, low-grade inflammation is often a fairly silent condition. This type of inflammation involves elevated levels of inflammatory compounds in the blood, such as interleukin 12 and c-reactive protein, which keeps your immune system constantly on edge.
Atherosclerosis (19), cardiovascular disease (20), obesity (21), and colon cancer (22) are just some of the many disorders that are associated with elevated levels of inflammatory biomarkers in plasma. Chronic low-grade inflammation can be a consequence of chronic health problems, such as in obesity where fat tissue releases many inflammatory mediators, but it’s also clear that inflammation can be a cause of disease. In light of all the research linking inflammation to chronic disease, the million dollar question becomes: Where does this inflammation stem from? Researchers have come up with many possible explanations, but a general consensus seems to be that the gastrointestinal tract plays an essential role. The entire digestive machinery in the human body is essentially on the outside of our body in the sense that it’s constantly bombarded with antigens, food, and microorganisms we ingest. The gut is the most important interface between us and the external environment, and since we know that about 70% of our immune system is located in or around the gastrointestinal tract, it quickly becomes evident that diet has a significant impact on our overall health (23).
But how does all of this relate to saturated fat? Contrary to what a lot of people believe, the human digestive system is not a static machinery made up of the stomach and intestines, but rather a dynamic environment made up of trillions of bacteria, fungi, and viruses that play an essential role in the digestion and absorption of food. The gut microbiota – the collection of microorganisms living in the gut – changes in accordance with our diet. If we eat plenty of vegetables, the bugs that are responsible for breaking down complex carbohydrates get a chance to flourish, while a ketogenic diet exclusively composed of fat and protein will lead to a quite different composition of gut bacteria. While most of the germs that live in and on our body are commensal organisms that live in harmony with the human host, some can also turn against us if they get a chance.
Some types of gram-negative bacteria contain a substance in their outer wall called Lipopolyssacharide (LPS). Pathogen-associated molecular patterns such as LPS are molecules that are commonly part of or shed by microbes and can trigger an inflammatory response in the body if they are allowed to enter systemic circulation. While everyone has a certain amount of these endotoxins in their blood, chronically increased plasma LPS concentrations (endotoxemia) can initiate low-grade chronic inflammation and obesity, diabetes, and cardiovascular disease (24,25,26). During the last couple of years, more and more reasearch is starting to suggest that alterations in the gut microbiota, increased intestinal permeability, and endotoxemia could be the keys to understanding a lot of the so-called diseases of civilization (27,28,29).
Bottom line: Most of our immune system is located in and around the gastrointestinal tract, and it’s therefore no surprise that a poor diet, altered gut microbiota, and loss of intestinal barrier function have been linked to a myriad of chronic diseases.
There are many aspects about the western diet and lifestyle that can increase the translocation of LPS, such as antibiotics and refined carbohydrates, and during the last couple of years we’ve also learned that fat intake regulates the absorption of lipopolysaccharide. Since chylomicrons (fat transporters) promote intestinal absorption of lipopolysaccharides, it’s no surprise that the amount of fat you eat has a significant impact on the levels of LPS in your blood (30). Although chylomicrons and other lipoproteins are part of our innate immune system and have the ability to inactivate LPS, one recent study showed that chylomicron-associated LPS could contribute to the inflammatory response associated with a high-fat meal (31,32). LPS can also enter systemic circulation by other means, like when bacterial imbalances in the gut have allowed the gut wall to become leaky (increased intestinal permeability).
Let’s have a look at what the studies tell us about high-fat diets/meals and low-grade chronic inflammation:
It could be that one of the reasons why LPS levels in serum increases after a high-fat meal/diet is that the increased lipid concentration in the intestine promotes an environment where LPS-containing bacteria are allowed to flourish and levels of good bacteria decline. This altered microbiota results in a decreased expression of tight junctions proteins that help regulate intestinal permeability and thereby increased translocation of substances like LPS.
Bottom line: A high fat diet/meal can induce low-grade chronic inflammation under the right conditions, but prebiotics and antioxidant rich foods can help neutralize the inflammatory response.
But what does this mean exactly? Should we stop eating fat altogether to reduce the absorption of endotoxins? Of course not. Lipids have been an important part of the human diet for hundreds of thousands of years, and there’s no reason to believe that we suddenly aren’t adapted to digest foods that are high in fat. If we simply look at the studies it might seem that all low-carb dieters have elevated levels of inflammatory substances in their blood, and while some probably do, there’s clearly something else going on here. Is the high-fat content in the diet the problem, or are other factors involved? How can some non-westernized populations thrive on high-fat diets if these diets supposedly wreak havoc on the immune system?
It could be that this response to a high-fat meal is a mechanism we have evolved to store more fat in times of food abundance, since endotoxemia sets the stage for insulin and leptin resistance, thereby promoting fat storage. When our hunter-gatherer ancestors killed large game and suddenly had the opportunity to gorge on fatty organ meats, this postprandial enxotoxemia could have allowed them to store more fat for scarcer times. But what about the semi-nomadic kenyans who eat a high-fat diet year round? How do these populations stay so slim? Genetic factors and the fact that they don’t have unlimited access to food – unlike people living in affluent nations – probably play a role, and there are also several other factors that can explain why the results from the studies above don’t necessarily apply in real life:
1) First of all it’s important to note that the high-fat diets used in most of the studies above were virtually devoid of plant food, meaning that these results don’t indicate that a high-fat diet is necessarily bad for you. In the real world, even those people eating ketogenic diets (<50 grams carbohydrate/day) typically consume some vegetables and/or nuts.
While most of the bacteria in our body live in the large intestine, the small intestine also harbors a diverse community of critters. The small intestine is also where dietary fats are predominantly absorbed. The problems associated with a high-fat meal seem to revolve around the proliferation of bad bacteria, the declining levels of good bugs like bifidobacteria, and reduced expression of tight-junction proteins. What this means is that if you’re eating a diet that is high in fat, especially saturated fatty acids, you should probably also make sure you’re eating plenty of fermentable fibers (found in onions, leeks, green bananas, and other plant foods) and other foods that help maintain a healthy gut microbiota and intestinal barrier.
2) A lot of the studies linking a high-fat meal with endotxemia have focused on very dense sources of fat, such as cream and GHEE, and the high levels of lipids in the intestine following the consumption of these calorie dense products could have have a different effect than eating organ meats, coconuts, etc.
3) Widespread use of antibiotics, c-sections, western diets, and other factors associated with life in the industralized world perturb the balance of bacteria that live in the gut, and some researchers have now begun talking about a westernized microbiome that have lost the original diversity and balance of the hunter-gatherer microbiome. So, one of the reasons the Maasai are able to stay lean and healthy “despite” eating a diet with plenty of saturated fat is probably that they have a much healthier gut microbiota than westerners, with lower levels of PAMP-harboring microbes. Also, while many westerners seek out the leanest and best-looking meats they can find, non-westernized populations typically eat the entire animal, including the chewy parts of the meat that contains complex carbohydrates.
Bottom line: A high-fat meal or diet can induce low-grade chronic inflammation, but prebiotics (and possibly fermented foods or antioxidant rich drinks) and a healthy gut microbiota/intestinal barrier can help protect against the translocation of bacterial endotoxins from the gut. The inflammatory response seems to depend on the quantity and sources of fat consumed. Highly concentrated sources of fat, such as cream and GHEE, probably have a different effect than meats and coconuts.
Let’s go back to the original question in the introduction: Should we trust the official dietary recommendations, or should we abandon the the notion that saturated fats are bad for you? Altogether I think it’s safe to say that the answer seems to lie somewhere in between.
Saturated fat has been an important source of energy in the human diet throughout our evolution, and many healthy populations around the world have thrived on diets that are rich in coconuts, meat and/or dairy. Also, a lot of the most recent studies question the notion that saturated fats are bad for you.
However, the fact that hunter-gatherer tribes and semi-nomadic people are healthy on high-fat diets doesn’t mean that a high intake of saturated fat is necessarily optimal in the context of the western diet and lifestyle. Sun exposure, genetics, superior food quality, physical activity, exposure to microorganisms, etc. could help explain why non-westernized populations are able to thrive on diets with plenty of saturated fat. Also, “new” processing techniques have allowed us to create products with a higher fat content than what is found directly in nature, and although a lot of these foods, such as coconut oil and butter, aren’t bad for you, they are less satiating per calorie compared to meats, vegetables, and fruits.
A high fat diet/meal can induce a state of chronic low-grade inflammation by promoting the absorption of endotoxins from the gut, but prebiotics and antioxidant rich foods seem to have the ability to neutralize this inflammatory response.
Bottom line: Grass-fed meats, free-range (organic) eggs, coconut meat, and other “unprocessed” sources of fat are very healthy. Butter, coconut oil, GHEE, cream, etc. can also be a part of a healthy diet, but they aren’t especially filling per calorie and could promote an inflammatory response if eaten in excess (under the right conditions). Oils and dairy products with a very high fat content are often combined with other foodstuff, and we can therefore end up with a highly palatable product that potentially overwhelms the reward center in the brain. If you’re eating plenty of saturated fat, it’s especially important to also take care of your microbiome and include a fair amount of plant foods in your diet, in order to neutralize the low-grade inflammation associated with a very high fat intake.
Name: Eirik Garnas
Besides studying for a degree in Public Nutrition, I’ve spent the last couple of years coaching people on their way to a healthier body and better physique. I’m educated as a personal trainer from the Norwegian School of Sport Sciences and also have additional courses in sales/coaching, kettlebells, body analysis, and functional rehabilitation. Subscribe to my website and follow my facebook page if you want to read more of my articles on fitness, nutrition, and health.
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