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Saturated fats are another topic that has stirred up controversy in the field of nutrition for quite some time.
The government recommends limiting saturated fat consumption to less than 10% of total energy intake to reduce the risk of heart disease, but there is a growing number of people encouraging the consumption of more saturated fat...
Who is right?
Just like with any topic, there is a lot more nuance that needs to be added to this discussion, and in this article, we will get into more detail about:
- Saturated fat types and where they are found in foods
- How different fatty types have different biological effects
- Evidence of the role of saturated fat on various health outcomes
- Practical considerations for your saturated fat intake
What is a Saturated Fat?Photo by Frank Zhang on Unsplash
Saturated fats are one of the two major classifications of dietary fats. There are unsaturated fats which are comprised of polyunsaturated fats and monounsaturated fats and then there are saturated fats.
These classifications are based on chemical properties, not health value. Saturated fats have no double bonds on their carbon chain and tend to be solid at room temperature (although some saturated fats can be liquid such as coconut oil
Unsaturated fats have at least 1 double bond on their carbon chain. Monounsaturated fats have only 1 double bond, and polyunsaturated fats have more than 1 double bond. Unsaturated fats are liquid at room temperature.
Each of these groups can be further broken down into several subgroups and dozens of individual fatty acids which we will discuss a bit more later.
We have discussed a specific type of polyunsaturated fats, the Omega-3 fats in episode #6 of the podcast which you can find here.
We will likely discuss Omega-6 polyunsaturated fats and monounsaturated fats in more depth in future episodes of the podcast, We will also cover them a bit here, because many studies compare saturated fats to other fat sources, but the focus of the show today will be on saturated fats.
First, let’s get more into the types of saturated fats, how they impact metabolic and cardiovascular health, and how to make practical decisions about your saturated fat consumption.
Types of Saturated Fatty Acids
As I mentioned above saturated fats are classified based on their chemical structure.Within this group of fats there are different fatty acids that have different carbon chain lengths, these are generally split further into, short, medium, and long chain saturated fats.
- Short chain = 2-6 carbons
- Medium chain = 6-12 carbons
- Long Chain 13-21 carbons
Saturated Fatty Acids in the Human DietPhoto by Szabo Viktor on Unsplash
- Stearic acid: 18 carbon atoms long – Beef Tallow, Lard, Butter, Chocolate
- Palmitic acid: 16 carbon atoms long – Primary fat in meat and dairy and palm oil, and also ¼ of fat in chocolate, and a smaller % of the fat in olive oil
- Pentadecylic acid – 15 carbons long – Found primarily in dairy fat, but makes up a small % of it
- Myristic acid: 14 carbon atoms long – ~15% of FA in Coconut oil and palm oil, ~10% in butter, 2-4% in beef and lamb.
- Lauric acid: 12 carbon atoms long- Primary fat source in coconut and palm oil.
- Capric acid: 10 carbon atoms long - MCTs found in palm, coconut oil, and dairy.
- Caprylic acid: 8 carbon atoms long - MCTs found in palm, coconut oil, and dairy.
- Caproic acid: 6 carbon atoms long - MCTs found in palm, coconut oil, and dairy.
There are also SCFAs that have shorter carbon length, which include butyric acid, propionic acid, and acetic acid. These are primarily formed by microbes in our intestines when they break down fibers and carbohydrates that we don’t digest well. These fatty acids are thought to have several positive health promoting effects and are thought to be responsible for some of the beneficial effects of fiber consumption. We can get also get a small amount from butter and other dairy products, but it is a very small % of the total fatty acid content of these foods (1).
Short and medium chain fatty acids are metabolically different than long chain fatty acids due to their smaller structure. These fats can be absorbed into the bloodstream without being packaged into triglycerides and chylomicrons, which is how other fatty acids are absorbed and transported. For this reason medium chain fatty acids are a more readily available source of energy, They are also more easily converted into ketones in the liver than other fatty acids. Ketones can provide an alternative fuel source to glucose for the brain so they can provide energy when blood sugar levels are low (2).
The most common dietary medium chain fatty acid is the 12-carbon fat, lauric acid which is the primary fat in coconut and palm oil. These oils also have small amounts (10%) of caprylic, capric, and caproic acid as well, and dairy dairy also contains small amounts of each of the MCFAs with under 5% of total fatty acids coming from capric, caprylic, and caproic acid (3).
The longer chain saturated fatty acids include the 14 carbon myristic acid which can be found in coconut and palm oil and to a lesser extent dairy fats, the “odd chain fats” which are the 15 and 17 carbon fatty acids that are mostly found in dairy foods and the 16 and 18 carbon fats that are the primary fats in meat, tallow, lard, and butter. Palm oil is also rich in the 16 carbon saturated fat palmitic acid and chocolate is rich in both the 16 and 18 carbon saturated fatty acids.
The Role of Saturated Fats in HealthPhoto by Online Marketing on Unsplash
This is a general overview of the types of saturated fats and their food sources It’s important to note that every food contains a mix of fatty acids, not just one specific type of fat. Also, each food is made up of several types of fats including saturated and unsaturated sources in many cases.
So, when we want to consider the impact of saturated fat on health, I think that it is more practical to consider the impact of various food sources of saturated fat on health outcomes vs. looking at it from the perspective of individual fatty acids. For example, chocolate saturated fat vs. dairy saturated fat, etc.
In many studies these are all lumped together as total saturated fat, but some studies have separated different sources of saturated fats which has helped provide greater insight into this topic.
So now let’s discuss the studies that look at the relationship between saturated fat and health outcomes.
As you all should know by now, I like to focus on large studies that look at major health outcomes and study was recently published by the World Health Organization titled: “Saturated fat and trans-fat intakes and their replacement with other macronutrients: A systematic review and meta-analysis of prospective observational studies”.
The study compiled the results from 112 publications that included almost 3.7 million people. The authors reported a 15% lower risk of death from any cause for replacing 5% of total energy intake from saturated fats with polyunsaturated fats, a 15% reduction from replacing saturated fats with monounsaturated fats, and an 8% reduction for replacing saturated fats with carbohydrates (4).
These results are similar to those reported in a 2020 study from Kim and colleagues that showed a 5% reduction in risk of all-cause mortality with 5% increased consumption of polyunsaturated fats and also slightly higher risk of death from any cause and cardiovascular disease (3% each) and a 9% increased risk of death from cancer when comparing the highest vs. lowest intakes (5).
This is a consistent finding across studies. Greater consumption of total saturated fat is associated with higher risk of death from any cause and death from heart disease. There are some studies that do not show this outcome, but usually they are in unique populations, such as countries where saturated fat consumption is low. In these cases it is usually because the people eating the highest amounts of saturated fats in those studies are consuming much less than 10% of their diet and they aren’t reaching a threshold that would confer risk.
However, when we examine different sources of saturated fats, we get a different picture. For example, we don’t really see a relationship between dairy fats and any negative health outcomes (6. 7) and data from biomarker studies actually suggest that the “odd-chain saturated fats in dairy may have protective health effects (8).
Another saturated fat source that seems to offer unique effects is chocolate. A 2019 umbrella review on the health effects of chocolate showed that chocolate consumption as associated with reductions in risk for heart disease, stroke, and diabetes (9). Pure chocolate is made up of mostly saturated fats, but also includes some fiber and is a rich source of a class of micronutrients called flavonoids that may be responsible for its protective effects.
When we look at the bigger picture we can conclude generally that high saturated fat consumption can carry a slight increase in risk for death from any cause and heart disease, but the primary concern is likely saturated fats coming from meat. This may partially explain why red meat consumption has been associated with slightly higher rates of mortality (10).
Individual Variability in Response to Saturated Fat Consumption
An important point to note is that many of the negative health consequences from meat consumption is attributed to their ability to raise LDL cholesterol levels. Through a variety of mechanisms saturated fats can increase cholesterol levels and those from meat, eggs, and butter have a more pronounced effect than butter, and those MCFAs from coconut have an even lower impact (11, 12).
One of the reasons that there may be more controversy around this topic is due to the large inter-individual variation in response to dietary saturated fat consumption. There have been 14 genetic variants identified that can impact the response to dietary saturated fat consumption (13). So one person might experience a significant increase in LDL when they eat more saturated fat and another may experience no increase at all.
Therefore, the long-term risk of consuming higher amounts of saturated fats likely partially varies from individual to individual based on LDL responsiveness to saturated fat consumption.
Short Term Feeding Studies
There are also several studies that have shown negative effects of consuming high amounts of saturated fats in short term feeding trials.
For example, one study published in 2014 overfed participants either sunflower oil or palm oil for a period of 7 weeks and found that the palm oil increased visceral and liver fat accumulation relative to the sunflower oil (14).
Another study compared the effects of consuming butter, high PUFA margarine and walnuts, a high MUFA margarine and almonds, or a crackers and jam condition for a period of 2 weeks while controlling the rest of the diet.
This study showed deterioration in flow mediated dilation, an assessment of the blood vessels ability to dilate, along with an increase in several markers of inflammation in the butter group relative to the other groups (15).
These findings are also supported by a 2018 study that overfed participants either a combination of saturated fats, unsaturated fats, or simple sugars for a period of 3 weeks and found that the saturated fat condition contributed to increased insulin resistance and liver fat accumulation to a greater degree than the other conditions (16).
A proposed mechanism of this effect is the activation of inflammatory responses by various saturated fats particularly palmitic acid and lauric acid (17, 18)
Should You Limit Saturated Fat in Your Diet?Photo by Outcast India on Unsplash
I know this is a lot to take in, so let’s conclude with some practical takeaways.
- Saturated fats are a diverse group of fats found in a variety of different foods, including meat, dairy, coconut, and dark chocolate.
- On a population level, consumption of total saturated fats is associated with minor increases in risk of death from any cause, heart disease, and cancer.
- This association appears to be specific to saturated fats in meat, not those found in dairy or chocolate, and is likely mediated by LDL cholesterol levels
- Saturated fats can also promote inflammation at high levels, particularly those rich in meat, palm, and coconut oil.
- Limiting consumption of saturated fat from non-chocolate sources is probably a good idea, particularly if you are someone who has high LDL cholesterol
- Dietary guidelines to limit saturated fat consumption to less than 10% of total calories is likely a good idea for most people
- Focus should be on limiting saturated fat from palm oil, meat, butter, and to a lesser extent, coconut and dairy fat, but not chocolate.
Curious to learn more? Listen to the in-depth discussion on saturated fats and more at the Nutrition Science Podcast.
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