Is Saturated Fat Bad For You?

Every year, more people die from cardiovascular disease (CVD) than anything else [1]. Thankfully, cardiovascular disease risk can be significantly reduced by lifestyle modification. Both exercise and healthy nutrition are powerful variables that can significantly reduce the risk of CVD. One of the hot topics when it comes to nutrition and CVD risk is that of saturated fat.

Saturated fat is often demonized due to its historical association with heart disease. However, recent research has provided a more nuanced perspective on the role of saturated fats in cardiovascular health. As we delve deeper into this subject, we'll uncover the truths, myths, and practical takeaways surrounding saturated fat intake and its influence on cardiovascular disease.

In this article, we will:

Discuss the relationship between saturated fat and CVD
Review the latest research on saturated fats and their effects on cardiovascular health
Provide you with some practical recommendations on whether or not you need to focus on your saturated fat intake

Let’s get into it!

What is Saturated Fat?

To start, it’s important to understand what saturated fats are. Saturated fats, as the name implies are a classification of dietary fats that are characterized by their chemical structure. On a molecular level, all fat molecules consist of a chain of carbon atoms bonded to hydrogen atoms. Each carbon can only bond to a certain number of hydrogens, typically three. Saturated fats are fats where each carbon atom is bonded to the maximum number of hydrogen atoms, thus it is a “saturated” fat. Fats whose carbon chain is not fully bonded to the maximum possible number of hydrogen atoms are what we call unsaturated, or poly-unsaturated fats.

This might sound complicated, but just understand the fact that since the carbons in saturated fats are maximally bound to hydrogen atoms, saturated fats have a different three-dimensional structure compared to other fats. They are more “straight” and “rigid” in nature.

Why does this matter?

Well, their chemical structure, in part, is important for their physiological functions. We often think of unsaturated fats as healthy fats that have important functions for our health, and saturated fats as useless, but that isn’t true. Saturated fats have very important physiological functions. For example, aside from being used for energy production, saturated fats play an important role in cell membrane structure. The outer wall of virtually all human cells is composed of a phospholipid bilayer. Think of it like a sandwich made of fat molecules that form the outer covering of cells. This phospholipid bilayer is made up of two layers of fat molecules, the majority of which are saturated fat molecules. Since saturated fats have a “straight and rigid” structure, they help with maintaining membrane stability and structure. To say that saturated fats are useless, simply is not true.

Where do we get saturated fat from?

People often thing that saturated fats are only found in animal foods, and while most animal foods do contain saturated fats, they can also be found in some plant-based foods.

Animal Products: Saturated fats are prevalent in animal-based foods, including red meat, poultry, full-fat dairy products such as butter, cheese, and whole milk, as well as in fatty cuts of meat like bacon and sausages.

Processed Foods: Many processed and packaged foods contain saturated fats. These can include baked goods, fried foods, snack items, and certain margarines and spreads.

Coconut and Palm Oils: Saturated fats are also found in plant-based oils like coconut oil and palm oil. These oils are often used in cooking and food processing.

Saturated Fats and Cardiovascular Risk

Next, let’s discuss the mechanisms that link saturated fat and cardiovascular disease risk. Mechanistically, the link between saturated fat intake and CVD is based on several mechanisms that impact low-density lipoprotein cholesterol (LDL-cholesterol), which is what we know as “bad cholesterol.” This nomenclature is faulty because it oversimplifies a complex biological process and can lead to misconceptions about cholesterol's role in the body. That being said, LDL cholesterol is a lipoprotein (a molecule made of mainly proteins and fats) that is produced by your liver and secreted into your bloodstream and carries cholesterol to different parts of your body, including your arteries. When you have too much LDL cholesterol, it can become a problem because:

If there's an excess of LDL cholesterol, it can stick to the walls of your arteries, kind of like gunk building up in a pipe. This can make your arteries narrower and stiffer.
Over time, this buildup can grow and harden, forming plaques. These plaques can block or narrow the arteries, making it harder for blood to flow smoothly.
When your arteries are narrowed or blocked by these plaques, your heart has to work much harder to pump blood. This can lead to chest pain (angina) or even cause a heart attack if a plaque ruptures and blocks an artery completely.

There is evidence showing that saturated fats can increase LDL production in the liver [2], which is the main argument against consuming saturated fat for CVD risk reduction. However, there is also evidence that saturated fat decreases the activity of LDL receptors that play a crucial role in removing LDL cholesterol from the bloodstream [3]. Furthermore, saturated fat consumption has been shown to increase the concentration of certain inflammatory molecules that are associated with the progression of CVD as well [4]. As we can see, the effects of saturated fat, at least mechanistically, are multifaceted and don’t seem to positively affect CVD risk.

What Does the Research Say?

Although mechanisms are great for helping us understand why something may occur, it’s incredibly important to look at studies that assess cardiovascular risk to make conclusive statements about the potential adverse health effects of saturated fats. Unfortunately, like most topics in nutrition, the answer to whether or not saturated fats are really bad for us is not that straightforward. There is evidence supporting the notion that we should reduce the risk of saturated fat to reduce CVD risk, but also evidence that doesn’t support this hypothesis for a number of different reasons.

Thankfully, there are two fantastic review articles published in 2020 by Dr. Krauss and Dr. Kriss-Etherton, two leading researchers in the field of nutrition and cardiovascular health, reviewing this topic that detail both the supporting and opposing evidence for the effects of saturated fat intake on CVD risk [5][6].

Below I’ll summarize the main points presented on both sides of the argument.

Evidence for reducing saturated fat intake to reduce CVD risk

There is plenty of evidence showing that replacing saturated fat intake in the diet with unsaturated fats results in a reduced risk of CVD. For example, a 2015 cohort study including data from over 100,000 participants concluded that replacing 5% of total daily calories from saturated fat for an equal amount of calories from poly- and mono-unsaturated fats resulted in a 25% and 15% reduction in coronary heart disease, respectively [7]. A 25% reduction in coronary heart disease is huge. A meta-analysis published in 2014 evaluated the effects of different concentrations of linoleic acid in the blood and risk of CVD events [8]. Linoleic acid (LA) is a polyunsaturated fatty acid that is associated with positive health outcomes. The data showed that replacing 5% of total calories from saturated fat with LA resulted in a 9% lower risk of coronary heart disease events and a 13% lower risk of coronary heart disease deaths. These are two large scale studies of many that show reductions in CVD risk as a result of reducing saturated fat intake.

Data like these really support the hypothesis that consuming saturated fat is really bad for cardiovascular health. Up to this point, you’re probably convinced that removing all saturated fat from you diet will help you live longer and eliminate your risk of developing heart disease, but that isn’t fully true. There are some key counterpoints that are important to discuss to paint the whole picture.

Opposing evidence suggesting that saturated fat may not be that bad

The most compelling argument is that most of the studies that show a reduced risk of CVD with reduced saturated fat intake replace saturated fat intake with mono- or poly-unsaturated fats. Furthermore, there are data showing that when saturated fats are substituted with other nutrients other than mono- or poly-unsaturated fats, such as refined carbohydrates or trans fats, there is no difference in CVD risk, and perhaps even an increase in risk [6][9]. In other words, the reductions in CVD risk observed in the studies that replace saturated fat with unsaturated fat sources may be due to the health benefits of consuming unsaturated fats and not reducing saturated fat intake since studies that substitute saturated fat with other nutrients, such as refined carbohydrates, do not show the same benefits.

Furthermore, there’s evidence suggesting that not all saturated fats are equal in terms of cardiovascular effects. For example, there’s evidence showing that while saturated fat from red meat is associated with worse cardiovascular outcomes, saturated fat intake from dairy seems to actually have beneficial effects on your cardiovascular system [10]. It’s likely due to two specific saturated fatty acids, pentadecanoic acid, and heptadecanoic acid, which are found in dairy, that have been shown to have cardioprotective effects [11]. It’s likely due to the fact that these specific fatty acids have an “odd” number of carbons in their carbon chair rather than an “even” number of carbons, which influences the functionality of that specific fatty acid. This just goes to show how complex and nuanced nutrition and physiology can be.

Lastly, there are genetic influences as well. The potential negative effects of saturated fat are due to their ability to increase LDL cholesterol and conversely, the benefit of reducing saturated fat intake is that it may reduce LDL cholesterol concentrations, thus, reducing CVD risk. However, everyone doesn’t respond the same to reducing saturated fat intake. There is evidence that our genetics influence how much our LDL changes in response to saturated fat intake. For example, there are different alleles (versions) of a protein called ApoE, which is involved in cholesterol and fatty acid metabolism. Depending on what kind of ApoE allele someone has, lowering saturated fat intake may or may not have a large effect on LDL concentrations. Specifically, men who carry an ApoE4 allele have a greater reduction in LDL cholesterol in response to reducing saturated fat intake compared to other ApoE alleles [12].

As you can see, this stuff is really complicated. For these reasons, it doesn’t make sense to make a blanket recommendation that everyone should reduce their saturated fat intake to be healthier. There simply are too many “holes” in the argument. That being said, it’s also inaccurate to say that saturated fat doesn’t matter at all, because there is plenty of evidence that in many cases, substituting saturated fat intake for other fat sources does result in a reduced risk of cardiovascular disease. This is why recommendations need to be made on a “per person” basis. Below are some general things to think about when it comes to personally deciding whether it’s right for you to reduce your saturated fat intake.

Family History of Cardiovascular Disease: If you have a family history of heart disease, particularly if close relatives (parents, siblings) have experienced heart attacks or strokes, it's important to be proactive about your heart health.
ApoE4 Alleles: Individuals who carry the ApoE4 allele may be at an increased risk of cardiovascular disease. They may benefit from a diet lower in saturated fats to help manage cholesterol levels and reduce their risk of heart-related issues.
High LDL Cholesterol Levels: If you have elevated LDL cholesterol levels (often referred to as "bad" cholesterol) on your blood lipid profile, substituting saturated fat for other fat sources can be an effective way to lower LDL cholesterol and decrease your risk of atherosclerosis and CVD.
Weight Management: Maintaining a healthy weight is crucial for heart health. Saturated fats are calorie-dense, and a diet high in them can contribute to weight gain. Reducing saturated fat intake can be part of an overall strategy for weight management and heart health.

Putting it all Together

Overall, cardiovascular disease remains a significant health concern, but lifestyle modifications can substantially reduce its risk. The role of saturated fat in heart health is a topic of ongoing research and debate. While saturated fats have been historically associated with heart disease, recent studies reveal a more complex picture.

Saturated fats play essential roles in the body, particularly in cell membrane structure, and not all saturated fats have the same impact on cardiovascular health. Research shows that substituting saturated fats with unsaturated fats can reduce the risk of heart disease. However, it's crucial to consider individual factors, including family history, ApoE genotype, LDL cholesterol levels, and weight management, when making dietary choices.

Ultimately, dietary recommendations should be personalized to fit each person's unique health profile. It's essential to consult with healthcare providers or registered dietitians for guidance on saturated fat intake and overall heart health strategies tailored to individual needs. Maintaining a heart-healthy lifestyle remains a key priority for reducing cardiovascular disease risk.