In the world of nutrition, there’s no shortage of hotly debated topics. Few, however, have persisted as steadfastly as the one around saturated fats. For the last 50 years, the guidance to limit them has been so often repeated that it feels like a commonsense recommendation.
Yet, there’s a lot of evidence — including some recent research reviews — that continues to dismantle this advice, as well as saturated fat’s purported link to cardiovascular disease. Some studies even show that saturated fat intake may be associated with a few potential benefits, such a decreased incidence of stroke.
As it turns out, the blanket fear of saturated fat may have been misguided all along.
What is saturated fat?
Saturated fats appear solid at room temperature and occur naturally in a number of foods. Common sources include animal fats — such as those found in cheese, butter, eggs, beef poultry with skin — and certain tropical oils, such as palm and coconut oil.
From a chemical standpoint, saturated fats have bulky molecular structures, with hydrogen atoms connected to every carbon atom, which makes them very stable and a great fat to use in high-heat cooking. This is why when saturated fats are heated up, for example, they are less likely than unsaturated fats to become oxidized or rancid.
Conventional Dietary Recommendations
Most of the current guidance around saturated fats dates back to the mid-20th century when the “diet-heart hypothesis” was born, largely as the result of the work of a physiologist named Ancel Keys. This idea — now largely critiqued — proposed that dietary fat and cholesterol raise serum (total blood) cholesterol, which in turn raises the risk for heart disease.
Despite there being no causal relationship between saturated fat and coronary events — meaning saturated fat was never actually proven to cause a negative cardiovascular effect — governmental nutrition policy responded to this hypothesis.
As far back as the 1970s, dietary guidelines recommended that Americans limit their overall fat intake. In 1973, the American Heart Association advocated that no more than 10 percent of calorie intake come from saturated fat. The U.S. Dietary Guidelines followed suit, with the recommendation persisting as a key advisement in their 2015 to 2020 Dietary Guidelines.
However, in recent years, multiple peer-reviewed research studies have suggested that it is diets high in refined carbohydrates and sugar — not saturated fat — that are behind the epidemic of cardiovascular disease. Here are several things to consider in order to better understand the role of saturated fat in our health.
Factors to Consider
1. Blood cholesterol levels do not tell the whole story.
Cholesterol is a waxy, fat-soluble substance that we need to survive. It gets transported around your body with carrier lipoproteins, including low-density lipoprotein (LDL) and high-density lipoprotein (HDL).
You may recognize those acronyms. Chances are you’ve heard of “bad cholesterol,” which refers to LDL, and “good cholesterol,” which refers to HDL. While commonly used, these groupings are oversimplified.
Swapping saturated fat for unsaturated fat (namely, vegetable oils) can lower your cholesterol and LDL. However, evidence shows this drop alone may not automatically translate to a lower risk of death from heart disease or heart attacks.
LDL cholesterol is not all bad, and lower isn’t always better. For example, one study showed that when LDL cholesterol drops below 70 mg/dL, the risk of hemorrhagic stroke increases.
There are also LDL subtypes and characteristics to be aware of in the bloodstream. The large, fluffy versions are less of a concern than the smaller, dense versions. (Note: You can do in-depth blood testing to better understand your LDL sizes and subtypes.)
Much of the literature suggests that the drop in LDL that occurs after the removal of saturated fat reduces the large, fluffier versions instead of the denser kinds that are more heavily implicated in the pathology of heart disease. The best way to know your personal patterns is to track them through lab testing over time, such as through a comprehensive assessment done annually.
2. Unsaturated fat sources can vary in quality and health impact.
Polyunsaturated fats are a type of unsaturated fat that can come from omega-6 fatty acids and better-known beneficial omega-3 fatty acids. When we swap saturated fats for unsaturated fats, our intake of polyunsaturated fats goes up, namely from vegetable oils rich in omega-6 fatty acids.
Proponents of the use of vegetable oils — such as corn, safflower, and soybean oils — cite that the increase in linoleic acid found in processed vegetable oils is heart-healthy. However, in the United States, the biggest source of linoleic acid comes from soybean oil, and it’s been suggested that increased use of soybean oil is linked to decreased tissue concentrations of the important, heart-healthy omega-3 fatty acids, such as EPA and DHA.
The marked increase use of these vegetables oils in our food supply has made a notable shift in the ratio of omega-6 fatty acids to omega-3 fatty acids that we consume, which can undermine our health.
Many of these processed seeds oils come with some additional concerns, including contamination with compounds such as glycidyl and monochloropropandiol. These contaminants have been identified as carcinogens in rodents and are being researched for potentially negative reproductive health implications in humans.
(For more about the different types of fats, read “The Facts About Fat.”)
3. Avoiding saturated fat can disproportionately increase your carbohydrate intake.
Fat provides satiety, mouthfeel, and flavor. When we reduce saturated fat in foods, however, starch, and sugar are often added to make the foods taste more palatable. We also often turn to foods that are high in added sugars, starches, and refined grains when we adopt low-fat diets. This surge in starchy carbs and sugar is problematic.
An estimated 100 million of us have some level of insulin resistance and altered tolerance to carbohydrates, meaning that we may not process carbohydrate-rich foods well. And alarming estimates predict that 40 percent of the U.S. population will have prediabetes in the next 10 years.
Those who are insulin resistant on some level (including prediabetics and type 2 diabetics) often also have high triglyceride levels, belly fat, alternations in blood pressure, and low levels of HDL cholesterol. This cluster of inflammatory conditions — which can raise the risk of heart attacks and cardiovascular events — is referred to as metabolic syndrome.
Studies have shown that lower-carbohydrate approaches (which are usually higher in fat, such as the ketogenic diet) can both reduce inflammation and support better outcomes in those with metabolic syndrome. One study concluded:
There is little need to further limit the intake of total or saturated fat for most populations. By contrast, restricting carbohydrate intake, particularly refined carbohydrates, may be more relevant today for decreasing the risk of mortality in some individuals.
By removing saturated fat (especially from natural sources such as eggs and cheese) and adding excess carbohydrates, you may likely see more trouble and metabolic disruption.
4. Saturated fatty acids in the blood are not the same as dietary saturated fat.
A lot of recommendations to avoid saturated fats note that circulating levels of saturated fat in the blood are linked to numerous chronic health conditions, inflammation, and metabolic issues. It’s easy to assume that saturated-fat intake is the problem, however, you may be surprised to learn that the saturated fats that you eat and the saturated fats that are in your blood are not the same thing.
Research has shown that in the context of a nutrition approach that moderates carbohydrate intake — even as dietary saturated fat intake goes up — our bodies produce less saturated fat to be released in circulation, and we also clear saturated fatty acids from the blood more efficiently.
As it turns out, plasma saturated fat is more closely tied with carbohydrate intake than it is to saturated fat itself. In other words, many of us can safely embrace full-fat yogurt, cheeses, red meat from grass-fed, high-quality sources, and eggs — and try to reduce our intake of refined carbohydrates and sugars.
As with any nutrition concept, prioritizing saturated fat sources from nutrient-dense foods (such as those listed) will incur more health benefits than those such as a takeout pizza or fast-food burger and fries.
5. Your genetics matter.
Genetically high cholesterol, or familial hypercholesterolemia (FH), is often marked by insulin resistance, excess body fat, inflammation, and blood-pressure issues. As a result, a lot of people with high cholesterol levels due to genetics respond well to an approach that moderates carbohydrate intake instead of reducing saturated fat intake.
However, there may be a few caveats to consider.
In a small subset of the population, there are people who may have a specific genetic variant that does make saturated fat intake contribute more strongly to the development of obesity. Yet other genetic predispositions have also been indentified that can dictate varying responses to saturated fat, monounsaturated fat, and carbohydrate intake that may not be consistent with the results of studies that show that the best approach may be carbohydrate restriction instead of fat restriction.
This proves the fact that we do not all respond to specific diets in the same way, and different approaches work for different people based on a variety of factors.
When determining the best nutritional approach for you, it’s important to start with a generally healthy template, and then, together with your medical team, monitor blood-test trends over time to see what objectively works best for you.
As you navigate nutrition and decide what to eat and what to limit in your plan, it’s important to remember that foods cannot and should not be categorized by a single nutrient. Most fat-containing whole foods offer combinations of several types of fat — saturated fat included.
When you look at foods with saturated fat, context is important. For example, dark chocolate contains beneficial antioxidants. Eggs contain choline, a key nutrient that supports liver, brain, and metabolic health. Yogurts and cheeses contain quality protein and minerals like calcium, phosphorus, and magnesium. Meat contains ample amounts of vitamin B12, creatine, iron, and carnitine. All of these foods all also contain saturated fat. If you avoided them for that reason, you’d miss out on their other benefits.
For a solid template to start with, focus on nutrient-dense foods in their most intact forms: plenty of vegetables, quality animal proteins, healthy fat from a variety of sources, and fiber-rich carbohydrates such as berries, beans, and lentils.