I began my career as a Registered Dietitian at a time when fat was bad stuff and saturated fat was particularly feared and reviled. As a student of nutrition I had been indoctrinated to this way of thinking which had taken hold decades earlier in the 1950s with Ancel Keys’s Six Country Analysis of Japan, Italy, England, Australia, Canada, and the United States.
Keys presented his findings with a graph that revealed a positive association between animal fat intake from meat and dairy, and death from heart disease. Although Keys’s graph was a very flawed analysis (details to follow), the association was a fascinating revelation at the time.
Rates of heart disease which had been practically unheard of at the turn of the 20th century had skyrocketed by the 1950s to become the number one killer in the Western world. Nobody knew what was causing this epidemic and people were desperate for answers. Keys’s analysis suggested by a leap of faith, not sound science, that somehow fat intake correlated to deadly cardiovascular events.
Are Animal Fats All Bad?
Animal fat would soon be equated to saturated fat but this is a myth, perpetuated so effectively over time that many people still believe it. The truth is that animal fats are generally only 50 percent saturated and some are more unsaturated than saturated. (See the list of Paleo sources of saturated fat in the Table below.)
Many authors including Gary Taubes, Nina Teicholz, and Denise Minger have chronicled the development of our collective thinking about diet and heart disease and how it was predicated on sketchy evidence from the start.
Keys’s six-country data analysis was deeply flawed and his critics knew it:
- Keys was accused of misrepresenting an association between his two variables as a causative relationship between diet and disease. However, association does not equal causation.
- He was criticized for cherry picking his data and graphing only those countries that supported his hypothesis. In fact, data was available from a much larger sample of 22 countries, and when all of them were graphed together, they showed not only a much weaker association between variables but that fat and protein and total calories had the strongest association with heart disease. And get this—total animal fat was actually associated with longevity!
- It was revealed that his data was gathered from the Food and Agriculture Organization (FAO) which represented how much food was available to people, not how much they actually ate. In other words, what Keys’s graph really showed was the relative wealth of his six countries by how many animal calories people had access to. Doh!
Nevertheless, Keys’s work caught the fascination of many scientists, journalists, and citizens alike. Determined to prove his theory further, Keys’s next project, the more meticulously designed landmark Seven Countries Study involving Greece, Finland, Japan, the Netherlands, Italy, Yugoslavia, and the United States, was launched in 1958 and ran until 1980. Data was still being extrapolated as recently as 2014.
Despite similar criticism to that of his Six Country Analysis (i.e. only seven countries were included this time; association does not equal causation; data was misrepresented, specifically from the Greek Island of Crete), Keys’s study gave the formerly obscure lipid hypothesis new life and it gave strength to his own diet-heart hypothesis which influences governmental nutrition guidelines to this day.
The Lipid Hypothesis
The lipid hypothesis states that high blood cholesterol causes heart disease and the diet-heart hypothesis states that saturated fat increases blood cholesterol, which increases risk for heart disease.
The diet-heart hypothesis gave the populace what it was looking for a cause for the runaway epidemic of heart disease and a plan to stop it in its tracks. People were told to reduce their dietary saturated fat intake to lower their blood cholesterol and, therefore, their risk for heart disease.
With industry-sponsored coercion from Big Sugar to deflect attention away from sugar’s role in the heart disease epidemic and the roar of very powerful voices blaming fat, including the American Heart Association (AHA) and the Dietary Guidelines Advisory Committee (DGAC) which controls USDA Dietary Guidelines policy, the counter-arguments of skeptics and critics went unheard (1).
Cholesterol Does Not Cause Heart Disease
The truth however, lay waiting to be found and after decades of exhaustive investigation it was. In 2015, the lipid hypothesis was officially debunked. Long-term, statistically-significant studies such as the Framingham Heart Study demonstrated that dietary cholesterol intake is not correlated with heart disease. In fact, it has been demonstrated that populations with the highest blood cholesterol levels have some of the lowest rates of heart disease and populations with the lowest cholesterol levels have some of the highest rates of heart disease in the world (2).
After 35 years of advising Americans to restrict cholesterol in their diets, the DGAC reversed over 30 years of policy and downgraded cholesterol from a “nutrient of concern for overconsumption” to—wait for it—nothing! Cholesterol was completely off the hook.
What about saturated fat? Independent of cholesterol, a growing mountain of scientific evidence has cleared saturated fat of its role in heart disease (3, 4, 5, 6). An extremely in depth review of the science is available here.
So, why would saturated fat remain a nutrient of concern (7)? The 2015 Dietary Guidelines continue to recommend that Americans reduce saturated fat intake to less than 10 percent of total calories and the AHA still recommends that it be even lower, at less than 7 percent.
I hope these population-wide guidelines will soon be in the same garbage pail as the old cholesterol guidelines. As we will see, although high saturated fat diets do have potential downfalls for certain population subgroups, official recommendations to reduce saturated fat to 10 percent or less is an old paradigm that needs to go.
Let’s chew the fat a bit, get to know the basics, and find out why saturated fat is a healthy fat!
A Basic Science of Saturated Fats: Fatty Acids and Triglycerides
Fatty acids are chains of carbon atoms (-C-C-C-) with a methyl group at one end (CH3) and a carboxyl group at the other end (COOH). One or two hydrogens attach to each carbon in the middle of the chain. When all of the carbons on a chain have two hydrogens attached, single bonds link the carbons together and the fatty acid is “saturated.”
Saturated fatty acids are straight and strong because they can stack compactly, one atop another. They are “healthy fats” because their saturation makes them very stable to oxidizers such as heat, light, and air.
If a fatty acid is missing hydrogens at adjacent carbons, a double bond forms and it is “unsaturated.” A fatty acid is monounsaturated if there is one double bond and polyunsaturated if there are two or more double bonds.
Fatty acid chains run in length from one to 24 carbons. In general, they’re designated as short chain if they have 1-8 carbons, medium chain with 10-14 carbons, and long chain with 16-24 carbons. Both fatty acid length and degree of saturation affect the physical and chemical properties of a lipid. (Lipid is the general term for fats and oils.)
Examples of Saturated Fatty Acids and Their Health Benefits:
- Short chain butyric acid with four carbons is the main source of nutrition for the epithelial cells in your colon and may also reduce the risk of inflammatory diseases such as Type 2 diabetes, obesity, IBS, Crohn’s disease, ulcerative colitis, and heart disease. Butyric acid is produced from fibrous foods in our gut, however it is also found in cheese, butter, ghee, and cow’s milk.
- Medium chain lauric acid with 12 carbon atoms is found in abundance in coconut oil and coconut products, palm kernel oil, and breastmilk. Medium chain fatty acids (MCFAs) have been shown to increase HDL cholesterol and provide an immediate source of energy via the formation of ketones. Ketones can improve memory in Alzheimer’s patients and greatly improve uncontrolled seizures in children. Furthermore, lauric acid as well as other MCFAs including capric acid and caprylic acid have antimicrobial, antiviral, and antifungal properties.
- Long chain palmitic acid with 16 carbon atoms is the most abundant saturated fatty acid in the food chain and so important to human biology that we can make it from carbohydrates and protein as needed. In turn, palmitic acid can make other fatty acids. It’s found in breastmilk, palm oil, cocoa butter, and animal fats.
All lipids are composed of triglycerides: three fatty acids attached to a glycerol molecule.
If a lipid is liquid at room temperature, it’s called an oil and if it’s solid, it’s called a fat. The more solid a fat is, the higher the degree of saturation.
Fact: almost all triglycerides contain a mixture of saturated and unsaturated fatty acids, which means that fats and oils from both plants and animals are not solely saturated or unsaturated.
10 Essential Roles of Saturated Fat
Naturally occurring saturated fat is so important for us that we start out life with a hefty dose of it. Saturated fat makes up approximately 50 percent of the fat of breastmilk! In fact saturated fat is so important, we actually make two of the longer chain saturated fats, palmitic acid and stearic acid, from carbohydrates and protein as we need them. The following are some of the important biological roles of saturated fat.
Cell membranes: Saturated fat is essential to the integrity and performance of every cell membrane in your body. It makes up 50% of the phospholipid bilayer which controls the flow of nutrients into the cell and and waste products out.
Brain: Medium chain fatty acids are converted to ketones that supply the brain (and the liver and heart) with energy.
Lungs: Our lungs are covered in surfactant which is made almost exclusively from palmitic acid. Surfactant makes air sacs more stable and prevents breathing disorders such as asthma.
Heart: Heart muscle is loaded with energy-producing mitochondria and very little carbohydrate reserve. It prefers to burn long chain fatty acids such as palmitic acid for fuel. (8)
Liver: Saturated fats can protect against alcoholic fatty liver disease, at least in rats and mice. (9)
Immune system: Medium chain saturated fats such as lauric, capric, and caprylic acids have well known anti-microbial functions. You can read more about medium chain fatty acids in this post.
Nervous system: Saturated fat appears to be very important for myelin formation especially in children. (10)
Hormone function: Short chain saturated fatty acids function as signaling messengers for hormone production including insulin and leptin. (11)
Blood lipids: Saturated fatty acids have been shown to decrease concentrations of an inherited form of atherogenic cholesterol known as Lp(a). (12)
Muscle mass: In mice, growth hormone release is upregulated by consumption of medium chain saturated fats. (13)
Are There Downsides to Saturated Fat Consumption?
There can be some downsides to saturated fat consumption, and Sarah Ballantyne, the Paleo Mom, illustrates several potential problems that it poses to our health.
Saturated fat can disturb our microbiome by creating destructive gut dysbiosis and endotoxemia (raised levels of immune stimulating endotoxins in the blood). Surprisingly, too much saturated fat may also disrupt our sleep!
Furthermore, saturated fat intake can greatly increase the risk of heart disease and Alzheimer’s in about 20 percent of the population that carries the ApoE4 gene. Others may be hyper responders to high saturated fat diets even if they don’t carry the gene. If your cholesterol increases dramatically after switching to a diet higher in saturated fats than previously, and you want to find out if you’re a hyper responder vs. an ApoE4 carrier, your doctor can order a test or you can do it yourself through a home genetic testing service.
Finally, very low fat diets where total fat intake is less than 10 percent of calories may be therapeutic for some people. You can read more about “carbosis” (as opposed to ketosis) from Denise Minger.
Saturated Fat is Healthy Fat
Healthy fats are those that occur naturally in plants and animals that do not oxidize easily when exposed to heat, light, and air and have not had their chemical structure harmed during their journey from farm to table. As we saw in the fatty acid section of this post, naturally occurring saturated fats from plants and animals fit these criteria.
Saturated fats do not cause heart disease on a population-wide basis. They play essential biological roles and come packaged in a delicious variety of foods full of additional unsaturated fats.
The diets or our Paleolithic ancestors are estimated to have been up to 58 percent total fat and 10-15 percent saturated fat. (14) Our current intake of saturated fat is about 11%. (15) Unless we have the unfortunate luck to be a hyper responder, or carry the ApoE4 gene, the idea that we need to limit our intake to levels lower than evolution prepared us for is without basis.
As Loren Cordain states in regards to saturated fats from natural Paleo sources in his book, The Paleo Answer, “The saturated fats you consume…will not promote heart disease, cancer, or any chronic health problem. In fact, these foods can ensure your birthright—a long, healthy, and happy life.”
Looking for some Paleo recipes rich in naturally occurring saturated fats? Look no further than our Recipe Center here at PaleoPlan. A few of my favorites include Lamb Ragu, Cashew Broccoli with Lemon, and Chocolate Coconut Drops.