Spoiler alert! What we are about to tell you may pleasantly surprise you. Saturated fat is not “bad fat.” Butter is back on the table! But don’t take our word for it. A recent state-of-the art review ( Astrup A. et al. 2020) by none other than the Journal of the American College of Cardiology (JACC) states directly:
“The recommendation to limit dietary saturated fatty acid intake has persisted despite mounting evidence to the contrary. Most recent meta-analyses of randomized trials and observational studies found no beneficial effects of reducing SFA intake on cardiovascular disease (CVD) and total mortality, and instead found protective effects against stroke.”
They go onto explain how saturated fat can increase LDL cholesterol, but that it tends to specifically increase the good kind of LDL cholesterol — the big fluffy friend that transports fat around the body, rather than the small dense foe that clogs up our arteries. The JACC further praises foods like whole fat dairy, unprocessed meat, and dark chocolate!
To watch our 5 minute video, click here.
State of the Art Review by the Journal of the American College of Cardiology (2020) states that there are “no beneficial effects of reducing saturated fat intake on cardiovascular disease and total mortality.”
Saturated Fats: Old Opinions Linger
So that’s the punchline. Now, for another important question: why do so many of us still believe foods like butter, cheese, and even coconut oil (the richest source of saturated fat) are going to give us heart attacks?
In large part, it has to do with how scientific data about food and health are collected. Some studies, called nutritional epidemiology studies, look at large populations of people for relationships between diet and chronic disease outcomes.
For example, we could explore how much butter, cheese, and meat are eaten in different countries and also the rates of heart disease in those countries. If there is a relationship between intake of saturated fat-rich foods and heart disease, then we could hypothesize that saturated fat contributes to heart disease. It’s a completely fair hypothesis.
The Problem with Epidemiology Studies
However, this kind of data collection comes with the very real possibility of multiple confounding variables. An example would be “healthy user bias.” We may all be told by public health messages that saturated fat is unhealthy, but those who follow this advice — or at least report that they do — may be very different from those who don’t.
Those who say they eat less saturated fat are also far more likely to report engaging in other behaviors that will lower their risk of heart disease. Furthermore, conscientiousness about health-related behaviors are strongly linked to higher education and income levels, factors that are almost always associated with better health in any case (Satia 2009).
In nutritional epidemiology studies, there’s no way to differentiate between the known health advantages of being wealthier and better educated, the potential impacts of other health-related behaviors, and the possible effects of what study participants eat.
Epidemiology, or association studies, are fine for generating hypotheses. But they are confounded by healthy user bias and confounding variables. They don’t determine cause-effect relationships.
In studies, the relationship between saturated fat and heart disease is so confounded by variables other than diet, it is impossible to rely on these correlations as evidence for a cause-effect relationship. This type of study isn’t designed to establish causation, yet the findings are sometimes reported in a way that makes them sound like a clear cause-effect relationship.
Inconsistencies in Epidemiology Studies
Another problem with epidemiological research is that it does not show a consistent association between intake of foods rich in saturated fat and cardiovascular disease.
For example, the PURE study, which included 135,000 people from 18 countries across five continents, found that increased consumption of total fat and saturated fat was not associated with increased cardiovascular disease and was, in fact, associated with a lower risk of stroke and a lower risk of death overall ( Ramsden C. et al. 2016)!
Such data don’t stand alone. Another study including almost 200,000 people who were followed for over a decade found no evidence that saturated fat intake was associated with cardiovascular disease, but rather that substituting certain polyunsaturated (such as those found in refined vegetable oils like soybean oil or corn oil) for saturated fats in the diet was associated with increased cardiovascular risk ( Ho FK. et al. 2020).
Randomized Controlled Studies, the Gold Standard
In science, once we have a hypothesis, we need to test it rigorously using interventional studies and randomized controlled trials in which groups of study participants are randomly assigned to two more different groups that undergo different treatments so that we can see how the treatments affect outcomes.
What do the randomized controlled trials tell us about saturated fat? Well, as the block quote above by the JACC revealed, randomized trials find no benefit of reducing saturated fat on heart disease. But, to illustrate the point, let’s give a specific example of such a study that is bound to shock you: The Minnesota Coronary Experiment.
The Minnesota Coronary Experiment
In this five-year randomized controlled trial conducted between 1968 and 1973, 9,000 people were provided with either saturated fat diets, containing milk, cheese, and meat, or low-saturated fat diets in which saturated fat was replaced with polyunsaturated fat from vegetable oil. (Nerd alert: Want macronutrient details? Here you go: the saturated fat diet was 18% saturated fat, 5% polyunsaturated fat, 16% monounsaturated fat, and 446 mg dietary cholesterol per day, and the vegetable oil diet was 9% saturated fat, 15% polyunsaturated fat, 14% monounsaturated fat, 166 mg dietary cholesterol per day.)
The study was intended to demonstrate that replacing saturated fat with unsaturated fat decreased heart disease risk. The data remained unpublished for sixteen years. When they were published, they found that “no differences between the treatment [saturated fat] and control groups were observed for cardiovascular events, cardiovascular deaths, or total mortality.” ( Frantz ID. et al. 1989).
In fact, the study found that decreasing cholesterol was associated with an increased risk of death ( Ramsden C, et al., 2016). Whoops! Again, were this study a one-off, we could dismiss it. But an evaluation of the existing and recent randomized trials confirms that reducing saturated fat intake does not improve cardiovascular risk ( Astrup A. et al. 2020).
Eating Low-Carb Decreases Saturated Fat in the Blood
A more recent randomized controlled trial further showed that eating a low-carb diet decreases saturated fat in the blood, even when you eat more saturated fat! This study ( Parker N Hyde et al. 2019) is a favorite of mine because of how rigorously it was conducted.
It was a crossover trial, meaning that all participants ate all the diets (high-carb, medium-carb, and low-carb) for four weeks each, so that each person could serve as her/his own control. Food was measured to the nearest 0.1 gram in a metabolic lab and provided to participants so that intake could be carefully controlled. All diets included the same number of Calories and protein and were individually adjusted so as to keep participants weight stable during the study. Thus, weight loss couldn’t be a confounding variable.
The study found that when participants ate the low-carb diet (including 100 grams of saturated fat), the saturated fat in their blood stream was far lower than when they ate the high-carb diet (including 40 grams of saturated fat).
Simply put, eating saturated fat does not mean more saturated fat in your blood. In the context of low-carb, you can eat more saturated fat because you’re eating less sugar and starch, which alters lipid metabolism and the production and burning of saturated fats. Oh, and the low-carb diet also increased levels of the healthy fat, DHA, decreased triglycerides, increased HDL, and reversed metabolic syndrome.
Say cheese! Actually, the authors do. “The results clearly support a role of the carbohydrate-to-fat ratio as having an impact on the response to high cheese intake.”
Types of Saturated Fats
Okay, we know your mouth is watering right now thinking about indulging in a slice of your favorite cheese, but don’t go quite yet! We still need to talk about the different kinds of saturated fats because, believe it or not, the saturated fatty acids in your coconut oil are not the same as those in your steak. Hmm… maybe that’s not a surprise.
What Are Saturated Fats?
So, what is a “saturated fat” anyway? Think of it this way: fats are like fish with straight or bendy tails. If a fish has a straight tail, it’s saturated. If it has a bendy tail, it’s unsaturated. (Nerd alert: For those who want more, these terms come from the relative number of hydrogen atoms attached to the carbon tails of fat molecules. If the carbon tail has all the hydrogens it can have, i.e. it’s saturated, that’s a saturated fat. If there are double bonds in the carbon tail, this creates bends and displace hydrogens such that fat is not fully saturated with hydrogen atoms.) So, when you look at a nutrition label and read “saturated” and “unsaturated,” the label is just telling you whether the fats in your food have straight or bendy tails. That’s it.
All that “saturated” fat means is the fat molecule has straight tails. Like fish on a coral reef, there are other ways in which fat molecules can vary. Let’s not do like nutrition labels and oversimplify.
But, if you’ve ever seen an image of a coral reef, you know that fish differ in many more ways than just having straight or bendy tails. Some tails are short, some are medium, and some are long. Some tails have one bend, some have many, and so on. When elaborating on fat diversity, let’s begin with fat tail length.
Short Chain Fatty Acids (SCFAs)
SCFAs are mostly made from the fermentation of fiber by our gut bacteria. Yep! Your microbiome lets you turn some fiber into fat. Don’t worry, it’s a good thing.
For example, butyrate is made in the gut and can help improve the health of your gut lining and even travel to the brain to improve neurological functions! You can get some butyrate from foods, like butter and ghee, although the amount is relatively low — about 4% of the fat in ghee is butyrate. (Being scientific sticklers, we do need to caveat this by saying low-carbohydrate diets can confer many of the benefits of butyrate by causing the production of the similar molecule, beta-hydroxybutyrate. Also animal connective tissues, and collagen, may also be fermentable into into SCFAs ( Depauw S et al. 2012).)
Medium Chain Saturated Fats
Medium chain fats are most popularly found in coconut oil. You can also buy pure medium chain fats called “MCT oil.” These fats are special in the way they are processed. Unlike longer chain saturated fats, which we will get to next, medium chain fats don’t go from the gut into your body’s main circulation but rather go straight to the liver via the hepatic portal vein.
Furthermore, while long fats need a special transport system to help them get burned for fuel (the carnitine shuttle), medium chain fats can move straight into your cells’ energy factories — your mitochondria — to be burned faster as fuel.
Because the medium chain fats in virgin coconut oil don’t require the carnitine shuttle to get into mitochondria, they get burned as cellular fuel more quickly, especially when you’re keto.
Long Chain Saturated Fats
Finally, long-chain saturated fats include those found in dairy, meat, and chocolate. They get their own paragraphs because most of the saturated fats you’re likely to eat come from these foods.
Dairy is the only source of fat in which the majority of fat is long-chain saturated fat. Analyses of the literature have found that intake of full-fat yogurt and cheese is associated with no change in or lowered risk of cardiovascular disease risk ( Astrup A. et al. 2014; Juo J. et al. 2017).
In fact, researchers can use particular odd-chain saturated fats as blood markers of dairy intake and have reported data suggesting an inverse association between dairy intake and heart disease. These odd-chain saturated fats have even been recently proposed, in the prestigious journal Nature, to be “essential” fats that may reduce the risk of not just cardiovascular disease but also obesity, inflammation, type 2 diabetes, fatty liver disease, and certain cancers ( Venn-Watson S. et al. 2020).
Even dolphins can benefit! An interventional study in which dolphins were fed a diet rich in these fats found that these saturated fats improved markers of metabolic syndrome ( Venn-Watson S. et al. 2015). Don’t you just love that! I guess dolphins have “straight” tails.
Choose Your Cheese Carefully, A1 vs. A2
Thus, including a reasonable amount of full-fat dairy in your diet is completely fine for most people. But, as an aside, we do want to caution you to, if possible, to opt for A2 dairy from goats, sheep, or buffalo.
The reason for this has to do, not with fat, but with proteins. Dairy from cows includes a pro-inflammatory protein called A1 casein, which can actually become an opioid, called BCM7, in your gut and can contribute to tummy troubles, autoimmune reactions, and inflammation (bad!).
Goat and sheep cheeses also contain smaller fat globules that are easier for some people to digest, while buffalo dairy has more antioxidant potential, than cow dairy. Some great common cheeses that are from goats, sheep, or buffalo include goat cheese, Pecorino Romano (substitute for Parmesan), Feta, Roquefort (Blue cheese), and Buffalo Mozzarella.
Saturated Fats in Red Meat
With respect to red meat, it’s always best to buy 100% grass-fed, which has healthier fats overall, including a better Omega-6/3 ratio to support lowered inflammation.
Another hot tip: lamb is particularly enriched in a fat called conjugated linoleic acid, which has numerous potential health benefits. And liver is a nutrient powerhouse! In fact, we can’t think of a more legitimate superfood than liver!
Saturated Fats in Chocolate
Finally, chocolate! Chocolate is awesome because it contains roughly equal parts oleic acid, the olive oil fat, and stearic acid, which we will just say treats your good LDL cholesterol and liver nicely.
Dark chocolate is also thought to be protective against cardiovascular disease overall, in part because of flavonoid polyphenols and ability to lower oxidative stress and inflammation ( Yuan S. et al. 2017).
Why Are Saturated Fats Good For Cooking?
The last topic we want to touch on before we wrap up is cooking fats and fat stability. One of the potential benefits of saturated fats is that they are heat stable, as compared to most major sources of unsaturated fat (avocado oil and macadamia nut oil are exceptions and are fine for cooking).
Ghee, tallow, and coconut oil are ideal for cooking. All have a heat resistance, or “smoke point,” of > 350F. Butter is fine too and, for those wanting to still keep their saturated fats on the low side, avocado oil is a great option.
When choosing a cooking fat, it’s best to go with those that are solid at room temperature, like ghee, butter, tallow, or virgin coconut oil. Avocado oil works too.
Evidence Says Saturated Fat is Not Harmful
Saturated fat isn’t actually a bad guy, the evidence does not suggest reducing saturated fat will improve your heart health, and including some whole foods sources in your diet is just fine for most people.
Saturated fats do vary widely, including in the length of their tails. Virgin coconut oil is rich in polyphenols and medium chain fats that are great fuel for cells because they can hop straight into your mitochondrial furnaces to be burned as energy.
Dairy is mostly saturated fat and you may choose to opt for dairy from non-cow sources to help reduce inflammation. Red meat should be purchased 100% grass fed (lamb and liver are also great) to optimize nutrient density and meat fat profile. Dark chocolate is great, full stop. (We hope you knew that already.) Ghee, butter, tallow, and coconut oil are good cooking fats because they are relatively heat resistant.
Edam! Did that just Roquefort your world or what? But you Feta believe we’ll Brie back with more updates as the science evolves!
Want To Learn More While Cooking Delicious Food?
Preorder the science-based cookbook that Martina and I, Dr. Nick Norwitz have coming out, in collaboration our friends Thomas DeLauer and Rohan Kashid.
This book is the first of its kind to include Omega-6 to Omega-3 ratios, full saturated, monounsaturated, and polyunsaturated fat breakdowns, and it's jam-packed with science and fun facts that will nourish not only your stomach but also your mind.
It comes out March 9, 2021. But if you if you preorder now by clicking here, we will send you bonus content, which you can then following these steps.
Take Home Messages
The likely myth that saturated fat causes heart disease comes from association studies that are problematic because of healthy user bias and confounding variables. These association studies, by nature, can’t show causation.
The strongest evidence suggests that saturated fat does not cause heart disease, as confirmed by the Journal of the American College of Cardiology (2020).
A “saturated” fat is simply one in which the fat molecule has a straight tail. Fat molecules vary in many more ways, including the number of tail bends, placement of tail bends, and tail length. These differences all impact fat metabolism.
Fat from whole-fat dairy, grass-fed red meat, and dark chocolate is not harmful, in the very least. These foods are more likely good for your health.
Ghee, butter, tallow, virgin coconut oil and other fats that are solid at room temperature are typically good for cooking, fake foods like margarine excluded.
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