Fats and oils is still a topic that confuses many people; even nutritionists! We have learned so much new information about fats and oils in the last decade that many people simply can’t keep up! So what is the difference between saturated and unsaturated fats? What exactly does the term healthy fat mean? Which fats should be avoided? Which are best to cook with? Today I am going to cover some frequently asked questions about fats. Please leave any additional questions in the comments!
Science warning! There is no way I can answer most of these questions without using science. I promise to try my best to keep it reader friendly! If you need any further translations or have any additional questions I am more than happy to answer them in the comments!
What exactly are fats and oils?
Fats and oils are one of the three macro-nutrients that our body requires to function. We obtain them in their pure form by extracting them from food sources such as animal fat, olives, herbs or spices (in the case of essential oils), and many others. Their main components are triglycerides which are molecules that are made up of 3 fatty acid molecules and 1 glycerol molecule. When digested, triglycerides break down into these components (fatty acids and glycerol). The fatty acids are the part of the triglyceride that makes a fat either saturated or unsaturated.
The words ‘fat’ and ‘oil’ are generally used interchangeably but there is a rough difference between them. Oils are generally liquid at room temperature, plant sourced, and composed mostly of unsaturated fat (some exceptions being coconut, palm, and fish oil), while fats are solid at room temperature, animal sourced, and composed of mostly saturated fat (source). Chemically speaking, there is no real difference between a fat and an oil.
What is the difference between saturated and unsaturated fats?
The fatty acids are the part of the triglyceride that makes a fat either saturated or unsaturated, and fatty acids are generally named after their molecular structures. Fatty acids are long chains of carbon and hydrogen ending in a carboxyl group (a chemical functional group). Saturated fatty acids have no double bonds (they are “saturated” with hydrogen). Unsaturated fatty acids have double bonds corresponding to their names; mono-unsaturated fatty acids have 1 double bond, while polyunsaturated fatty acids have 2 or more double bonds. Double bonds are more reactive/unstable than single bonds, thus the more unsaturated (more double bonds) the fat is, the more reactive or unstable the fat is. This means that unsaturated fats are more delicate and that is why they are usually stored in dark coloured glass bottles, refrigerated, and less often used for cooking (more information on cooking on page 2). Our bodies need both saturated and unsaturated fats to function optimally.
In this picture, palmitic acid is the least reactive or most stable fatty acid while EPA is the most reactive or unstable fatty acid.
Is all saturated fats the same?
Nope! Saturated fat can be further classified into a few different groups; short chained, medium chained, and long chained fatty acids. This refers to the length of the carbon chain of the fatty acid. Short chained are chains of less than 6 carbons, medium chains are chains of 6-12 carbons, and long chained are 13 or more carbons. In terms of digestion, short and medium chained fatty acids are more easily digested because they can be absorbed directly into the bloodstream while long chained fatty acids must go through the lymphatic system (source).
While coconut oil is mostly saturated fat, it is a unique source of medium chained saturated fats that you won’t get from many other foods in your diet. Long chained saturated fatty acids are mostly obtained from animal fats such as butter, lard, and meat. Short and medium chained saturated fats are not necessarily any healthier than long chained fats; all of these types of saturated fats are required for your body to function optimally. It is a misconception that long chained saturated fats (or animal fats) are bad for you (source). Variety of fats is the key to good health!
What you need to know about the omega-3 to 6 ratio
Most fats and oils contain some amount of omega 3 and omega 6 fatty acids. Our ancestors didn’t have to worry about this ratio because it was already ideal due to the fact they did not have access to refined vegetable oils or grain fed meat. The ratio of omega 3 to 6 that our ancestors would have obtained from their diet was approximately 1:1 or 1:2, therefore this is the ideal ratio (source). This ratio of omega 3 to 6 is associated with reduced inflammation and other autoimmune responses in the body. Many oils have an imbalanced ratio with a much higher amounts of omega 6. For example, sesame oil has an omega 3 to 6 ratio of approximately 1:140 (source). In excess omega-6 promotes cardiovascular disease, cancer, and inflammatory and autoimmune diseases (source). Therefore, it is best to avoid oils that are high in omega 6 for your overall health.
Oils that are high in omega 6 and low (or non existent) in omega 3 include:
- Safflower oil
- Grapeseed oil
- Corn oil
- Soybean oil
- Cottonseed oil
- Sesame oil
- Sunflower seed oil
- Almond oil and most other nut oils
- Animal fats that have come from animals not fed their natural diet (grain-fed)
If polyunsaturated fats are so unstable, what about foods that contain them?
Can cooking something high in polyunsaturates (such as salmon or nuts) destroy the omegas and negate the health benefits? This is a question that I always wondered about, and it turns out that it doesn’t really work like that (luckily!). When oils are contained within a food they are protected from oxidation by various antioxidants and other nutrients contained in the food (source). So as long as you aren’t cooking the living hell out of your food, you should be fine.
So what is a ‘healthy fat’?
This term is annoying because it is used wrong all the time! Some people are still under the impression that unsaturated fat is healthier than saturated fat (it’s not), so they term anything that is unsaturated as “healthy fat”. This leads to a lot of misconceptions as then people start terming soy and corn oil as healthy (it’s really, really not).
Healthy fat is any unadulterated fat, meaning not hydrogenated, refined, or heated (think deep fry). There are some exceptions to this rule, namely corn, soy, cotton seed, and other polyunsaturated fats that are high in omega-6; these are unhealthy in any form but are even worse when further refined or heated (see list above). Unhealthy fats are rancid fats, overly refined or processed fats, fats that have been extracted from genetically modified crops (due to pesticide concentration), hydrogenated oils (trans-fats), and any other fats that have a poor omega-3 to 6 ratio.