Dr. Kara Fitzgerald receives the Rosalind Franklin Society Special Award in Science
Fat is making a comeback! The “diet” and “low fat” craze has started to abate. Coconut is the new kale – it’s in every recipe, blog and health segment, not to mention at the end of every supermarket aisle! Grass-fed butter and ghee are back in. And, the doctors are weighing in – both Dr. Mark Hyman (Eat Fat, Get Thin) and Dr. David Ludwig (Always Hungry) tackle this controversial and often misunderstood topic on the fundamental role that fat plays in our diets.
This is a welcome trend, since we all know the critical importance of fabulous fats in our diet.
But does that mean we should go crazy for coconut? Or butter? Prioritize fats above all else? What is a healthy way to include fats? Fear not – we are here to help guide you! In this article, we cover the different types of fats that you should be including (in balance) in your diet.
There are several ways to categorize fats. You have probably heard many distinctions: saturated v. unsaturated, monounsaturated v. polyunsaturated, omega 3 v. omega 6. What does all of this mean? Let’s take a look.
How many carbons in that?
First, we have to understand fatty acids, the building blocks of all fats. Just like carbohydrates are made up of many glucose or fructose molecules and proteins are made up of many amino acids, fats are comprised of fatty acids. These fatty acids consist of chains of carbon (C) atoms, with hydrogens (H) attached. At one end, there is a carboxyl group (COOH) and at the other end, a methyl group (CH3). Figure 1 is an example of a fatty acid, capric acid, with 10 carbons. Capric acid is one of the fabulous medium chain fatty acids found in coconut oil.
Figure 1: Capric Acid
There are many different fatty acids found in nature, so we will focus on the most common and important types here. Fatty acids can be categorized based on their length (determined by the number of carbons they contain): short chain, medium chain, long chain and very long chain.
| Short chain (SCFA) | Medium chain (MCFA) | Long chain (LCFA) | Very long chain (VLCFA) | |
| Chemical composition | <6 carbon atoms | 6-12 carbon atoms | 13-21 carbon atoms | >22 carbon atoms |
| Commonly found in | Dietary fiber*, butter, ghee | Coconut oil, palm oil | Meats, dairy, fish | Fish |
| Examples | Butyric, acetic, propionic | Caprylic, capric | Linoleic (LA), alpha-linolenic (ALA), gamma-linolenic (GLA), arachidonic (AA), eicosapentaenoic (EPA) | Docosahexaenoic (DHA) |
*Produced when dietary fiber is fermented in the colon
Some of these fatty acids are considered essential, which means that they are not made in our bodies, so they must come from our diet; the two essential fatty acids in humans are linoleic acid (LA) and alpha-linolenic acid (ALA).
Saturated v. unsaturated fats
In addition to their chain length, fatty acids can also be distinguished based on whether they are saturated or unsaturated in nature. Each fatty acid can be classified as saturated, monounsaturated or polyunsaturated. However, fats themselves are often a combination of several types of fatty acids: for example, coconut oil contains both saturated and unsaturated fat and olive oil contains both monounsaturated and polyunsaturated fat.
Saturated fats are predominantly found in animal sources and are solid at room temperature. They do not contain any double bonds. When double bonds are formed, hydrogen atoms are eliminated. Therefore, a saturated fat is essentially “saturated” with hydrogen atoms. Saturated fats are composed of chains of fatty acids: in the case of animal fats, those fatty acids may be palmitic or stearic acids; in the case of plant fats, those fatty acids may be lauric or myristic acids.
Unsaturated fats, on the other hand, come predominantly from plant sources and are liquid at room temperature. They can contain one double bond (monounsaturated) or more than one double bond (polyunsaturated). The more double bonds, the more vulnerable the fat is to peroxidation or rancidity.
| Saturated | Unsaturated | |
| Physical composition | Solid at room temperature | Liquid at room temperature |
| Chemical composition | Contain no double bonds 
|
Contain at least 1 double bond 
|
| Types of fatty acids | Animal fats (palmitic, stearic, butyric); plant fats (lauric, myristic, caprylic) | Monounsaturated (oleic acid); polyunsaturated (LA, GLA, AA, ALA, DHA, EPA) |
| Commonly found in | Predominantly from animal sources (e.g., pork lard, beef tallow, butter); also certain plant sources (e.g., coconut, palm) | Predominantly from plant foods (e.g., nuts, seeds, olives) |
| Shelf life | Long | Short |
| Melting point | High | Low |
| Rancidity | Low | High |
Monounsaturated v. polyunsaturated fats
Within the unsaturated fat category, there are two types: monounsaturated and polyunsaturated. Monounsaturated fats have one double bond whereas polyunsaturated fats have more than one double bond. Again, many fats we eat are a combination of these two fats, but often have a predominant type; for example, coconut oil is 92% saturated, 7% monounsaturated and 1% polyunsaturated1. As we can see, it is predominantly a saturated fat and therefore will exhibit the properties that most closely resemble other saturated fats. Olive oil, on the other hand, is 14% saturated fat, 78% monounsaturated fat and 8% polyunsaturated fat1; it will demonstrate the qualities of a monounsaturated fat.
| Monounsaturated | Polyunsaturated | |
| Chemical composition | One double bond 
|
More than one double bond 
|
| Types of fatty acids | Oleic | LA, ALA, AA, EPA, DHA |
| Commonly found in | Almond oil, avocado oil, hazelnut oil, macadamia nut oil, olive oil | Grapeseed oil, safflower oil, walnut oil, fish, shellfish |
Omega 3 v. Omega 6 v. Omega 9 fats
Digging even deeper, there are three main types of fats within the polyunsaturated category: omega 3, omega 6 and omega 9. The numbers 3, 6 and 9 refer to the length between the carbon chain and the first double bond.
| Omega 3 | Omega 6 | Omega 9 | |
| Chemical composition | Contain double bond 3 carbons away from methyl carbon 
|
Contain double bond 6 carbons away from methyl carbon 
|
Contain double bond 9 carbons away from methyl carbon 
|
| Fatty acids | ALA, DHA, EPA | LA, GLA, AA | Mead |
| Produced in body? | ALA: No
DHA and EPA: Yes, but the process isn’t very efficient |
LA: No
GLA and AA: Yes |
Yes |
| Examples | ALA: Plant sources (e.g., walnuts, flaxseed, sunflower)
DHA, EPA: Animal sources (e.g., salmon, tuna, trout, mackerel, sardines) |
LA: Plant sources (e.g., safflower, sunflower, walnut)
AA: Animal sources (e.g. meat) |
Plant sources (e.g., olive oil, macadamia nut oil, avocado) |
Our advice in a nutshell: Variety and quality are key
There is no one fat intake that is right for all people; some people tend to do well on high-fat diets while others tend to do well on lower-fat diets. In all cases, we need varied fat to survive and thrive. Fat is essential to many critical functions in your body (e.g., energy, insulation, vitamin absorption and storage, hormone production, shock absorption). A human brain is more than 60% fat! Regardless of the amount of fat in your diet, choosing high quality fats will make all of the difference in how your body processes and uses the fat.
A diet that contains monounsaturated fats has been linked with lower cholesterol and less heart disease, as well as better weight management. Eat a variety of monounsaturated fats to get the most widespread benefits. Great sources of monounsaturated fats include olive oil, avocados and nuts (e.g., almonds, cashews, pecans, macadamias).
The story with polyunsaturated fats is a bit more nuanced. The ratio of polyunsaturated fats is a critical predictor of how healthful these fats will be in your body. Today, many Americans are overconsuming omega-6 fats. Moreover, they are not consuming enough omega-3 fatty acids as a counterbalance. It’s not the presence of omega-6 fatty acids in and of itself that causes trouble (they are, after all, still essential fatty acids), but rather the ratio of omega 6:omega 3 fats that can be a problem. Many people are consuming omega 6:omega 3 fats in a ratio as high as 20:1, but the optimal range is somewhere from 1:1 to 3-4:12. An imbalance in the ratio between omega-6 and omega-3 fats is associated with increased inflammation and has been linked to many health conditions (e.g., cancer, heart disease, diabetes, autoimmune disease). To optimize this ratio, you can both check your omega 6 intake (e.g., by avoiding vegetable oil, processed foods, fast food) and raise your omega 3 intake in balance with omega 6 (e.g., through walnuts, salmon, mackerel, herring, flaxseeds, chia seeds, hemp seeds, and grass-fed eggs).
Should I eat saturated fat?
Over the years, saturated fat has wrongly received a bad rep. I would encourage you to listen to (or read the transcript of) the recent podcast that Dr. Fitzgerald did with Dr. Mark Hyman on the topic of fats, including saturated fats. In it, he explains that most of the problematic lipids in our body, such as too many palmitic or stearic acids, are mainly produced in our liver from carbohydrates that we eat in our diet; though palmitic and stearic acids can be obtained from the diet, we primarily produce them in the liver in response to carbohydrate consumption. Dr. Hyman also explains that his research has led him to conclude that eating the combination of saturated fat with refined carbohydrates or sugars can be particularly problematic; it is the effect of the simple carbs in this equation that is most troublesome. Also, check out Dr. Fitzgerald’s conversation with David Ludwig, MD, PhD, who also reviews the reason why sugars are much more of a menace and driver for lipid dysregulation and high-risk cholesterol profiles.
High quality saturated fat is an essential part of a healthy diet when consumed as part of a whole foods, high-fiber based food plan and in balance with other unsaturated fats. Seek out grass fed / pastured raised meats and dairy or high quality plant oils (e.g., unrefined coconut, palm) for a healthy dose of saturated fat. And, avoid eating them with refined or high-glycemic carbs.
How do trans fats fit into this picture?
In an ideal world, they don’t. Trans fats are known to promote inflammation and have been associated with a host of diseases including heart disease, stroke, diabetes, and other chronic conditions.
Trans fats are usually created through a manufacturing process called hydrogenation, whereby hydrogen atoms are added to unsaturated fats; this change in chemical composition also causes a change in the fat structure – instead of being a liquid at room temperature, as we explained earlier, these hydrogenated fats now become solid or semi-solid at room temperature. This increases the shelf life of the fat and makes it of value to the processed food industry, which incorporates it into many packaged foods (e.g., chips, baked goods).
In 2013, the FDA initially determined that partially hydrogenated oils, the main source of industrially produced trans fats, were no longer “generally recognized as safe”. And in 2015, the FDA mandated that all food manufacturers stop using trans fat within three years.
The best way to avoid trans fats is to minimize your consumption of processed foods and check food labels carefully. Be aware that any foods containing less than 0.5 grams of trans fats can be rounded down to zero (and labelled “trans fat free”) so be sure to look at the ingredient list for “partially hydrogenated oils” as well.
So, there you have it! We hope you found this to be a helpful introduction to the fascinating world of fats. Don’t miss our other article on shopping for and cooking with fats to learn about choosing fats and different cooking temperatures.
Sources:
- Murray, Michael ND. Encyclopedia of Healing Foods. New York, NY: Altria Books, 2005.
- Wahls, Terry MD. The Wahls Protocol. New York, NY: Penguin Group, 2014.
This article was contributed by Alexandria DeVito, MS. Alexandria is a functional nutritionist, Eating Psychology Coach, yoga teacher and personal trainer. With a background in nutrition and fitness, she brings the best of both disciplines to help clients address any areas they may want to optimize in their lives (e.g., increasing energy levels, relieving digestive distress, losing or maintaining weight). Alexandria is dedicated to helping clients unlock their best selves in order to give and receive the most out of their relationships, work and life. Prior to becoming a nutritionist, she was a consultant to the pharmaceutical and medical device industry. Alexandria holds a Bachelor’s of Science in Business Administration from Georgetown University, a Master’s of Science in Nutrition from University of Bridgeport and a Master’s in Business Administration from Harvard Business School.
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Very well researched and written article, thank you. I’m hoping you can tell me about sesame oil — it’s qualities. I have been massaging daily with cured sesame oil to nourish my very dry skin and bones. I know it has a heating quality which helps with my aversion to cold where coconut has more of a cooling quality, but I don’t know abut it’s carbons and double bonding, and therefore it’s health giving properties as a daily, whole-body, massage oil. Thank you.
I keep getting a “deficiency” of oleic acid on a nutrient deficiency test and they said to take olive oil. I eat so much olive oil already and deficiency just gets worse. ha! Thanks for shedding light on the need for omega 6’s more than I am obviously getting in my meat and plants (as much as possible) diet. I’m going to add sunflower oil back in and see how that helps alleviate deficiency by retesting. Hmm….wonder why everyone is bashing veggie/seed oils if that is a great source of omega 6’s in diet?