Well, more specifically, let’s talk about dietary fats. There are a variety of different fats found in our foods, and all foods contain at least a tiny amount of fat. We’ve all heard of different fats referred to as “bad” fats or “good” fats, and there is some truth to this type of categorization. While some fats get an unfair bad rap, other fats should definitely be avoided if you’re concerned for your health, especially since fatty acids are what make up our cellular membranes, which are responsible for keeping our cells safe and functioning properly. In addition to this, fats play many roles in our bodies, including:
- Providing energy
- Supporting hormone production
- Supporting the immune system
- Aiding in fat-soluble vitamin absorption (A, D, E, & K)
- Allowing for the proper use of proteins
- Protecting our organs
- Increasing satiety (so you experience less nagging hunger pains)
- And making food taste pretty darn good. ❤
So let’s break it down, which fats are good? Which are bad? And why? To do this we must talk about the different types of fats, which can be broken down into three categories: polyunsaturated fats, monounsaturated fats, and saturated fats.
Polyunsaturated fats (PUFAs), are so named because of their molecular structure. Fats are a chain of carbon atoms linked together with surrounding hydrogen atoms to fill in the gaps. “Poly” means multiple, which indicates that the fat has multiple double-bonds in between carbon atoms, as indicated in the picture below.
The bends in their structure are what make the oils liquid.
Omega-3 and omega-6 fatty acids are the two types of PUFAs. Alpha-linolenic acid (ALA, an omega-3) and linoleic acid (LA, an omega-6) are the plant forms of omega-3 and omega-6 and are considered the two “essential” fatty acids because our bodies cannot synthesize them on their own, which means that the only way we obtain them is through consumption. But, ALA must first be converted into its animal-form counterparts–EPA and DHA before being utilized by the body; in the same way, LA must first be converted into arachidonic acid (AA). Sometimes Omega-3s are called “good” and omega-6s are called “bad”, but the reality is much more complex than that; both of these fats play an important role in our inflammatory processes. AA (O6) aids in increasing inflammation to kickstart healing and repair, and both EPA/DHA (O3) and AA (O6) aid in reducing inflammation once healing has taken place.
The omega-6 to omega-3 intake ratio that is so often talked about is more relevant to those who do not consume the animal forms of these fatty acids. This is because the plant form of omega-3 (ALA) and the plant form of omega-6 (LA) use the same mechanisms to be converted into their usable forms, so an excess of one will hurt the conversion rate of the other. In such cases, the ideal ratio lies between 1:1 and 4:1 omega-6 to omega-3. For those that do eat animal foods (including fish, egg yolks, and liver), the ratio may not be as important.
Omega-3 and Omega-6 Deficiency
Deficiencies in omega-3s and/or omega-6s are commonly related to poor conversion rates, especially for those that rely heavily on the plant forms of them. Also, plenty of high PUFA plant foods (especially nuts, seeds, and vegetable oils) contain very high amounts of omega-6 LA and lower amounts of omega-3 ALA, which can hurt omega-3 conversions. This is problematic for those that don’t consume pre-converted omega-3s (EPA/DHA). The richest sources of converted omega-3s (EPA/DHA) are egg yolks and fatty fish, so this may be you if you don’t include these in your diet. ALA and LA conversion/utilization can also be hindered by nutrient deficiencies, high sugar diets, oxidized vegetable oils (which I’ll discuss in a bit), low intake of any macronutrient, anti-inflammatory drugs and foods, and your genetics. Having inadequate levels of EPA/DHA can lead to neurological problems and mental/mood disorders; and low levels of AA can cause problems related to skin, hair, nails, libido, and fertility.
Polyunsaturated Fats: Oxidized oils
There is such a thing as a “bad” fat in the sense that these fats do nothing good for our health and actually cause damage. This is especially true for certain polyunsaturated fats. Because of the molecular structure of PUFAs, they are pretty unstable in that they are susceptible to oxidation from heat, light, and pressure exposure. This is what I was referring to above when I mentioned oxidized oils.
So why is consuming rancid oils bad for our health? Remember how I mentioned that fatty acids make up the cellular membranes that protect the cells and help them function properly? Well when we consume oxidized oils, they end up in our cellular membranes and cause free radical damage to our DNA, proteins, and other fatty acids in the membrane. If this happens consistently enough, it can lead to chronic inflammation and cause degenerative diseases, like heart disease, cancers, dementia, etc. Yikes! This is why it is very important that PUFAs be well taken care of prior to consumption. Unfortunately, high PUFA industrial seed oils are what are most commonly used for cooking–especially in restaurants–because they’re cheap and have a mild flavor. These types of oils (including soybean, safflower, canola, cottonseed, etc.) are extracted using high temperatures and pressures, which leave them oxidized by the end of the process. So, in order to avoid consuming oxidized PUFAs, it’s best to consume them in their raw, whole-food forms (like raw nuts and seeds). And if you consume them in oils–like flaxseed oil–it’s best to use those that have been extracted at low temperatures and pressures and are bottled in dark containers. They should also never be heated and should be stored in the refrigerator.
Remember how “poly” indicates multiple carbon double bonds? Well the “mono” in monounsaturated fats (MUFAs) means they only contain one, as indicated in the picture below.
The single bend in structure is what makes these oils liquid at room temperature, and a bit more solid in colder environments.
These fats are not considered “essential” simply because our bodies have the potential to synthesize them without consuming them, although this does not mean that they are not important. Monounsaturated fats may play a role in reducing LDL cholesterol and increasing HDL cholesterol, and may also help improve insulin sensitivity. Their chemical structure makes them a bit more resilient to oxidation compared to PUFAs, but still a bit susceptible to oxidation as described above. So it’s important that these oils only be heated at low temperatures, if at all.
Although saturated fat has long been demonized, it actually does some great things for us. Read more on how it gained such a reputation in this post. Saturated fats can be typically found in animal fats and tropical oils. Saturated fats actually do NOT contain any double bonds between carbon atoms, which makes them the most stable and ideal for cooking.
This saturation is what makes these fats solid at room temperature (unless you live in Texas, where “room temperature” can mean 80 degrees 😦 ). Saturated fats are also the easiest to digest of the 3 categories.
A Special Saturated Fat: Medium-chain Fatty Acids
This type of fat is a real gem. Often referred to as MCTs (medium-chain triglycerides), they actually do not require bile in order to be digested, making them the ideal fat source for people that have had their gallbladder removed. Some of these may also have antibacterial effects and enhance thermogenesis (which stimulates fat-burning) and cognitive performance. Medium-chain fatty acids can be found mostly in coconut oil, but dairy and palm kernal oil also contain smaller amounts.
Some fat-related issues may be controversial in the health space, but we can all definitely agree that trans fats are bad. Completely. “Poisonous” even. Trans fats are made when an unsaturated fat is “partially-hydrogenated” to the point where its chemical structure is altered so that it becomes more solid. These types of man-made fats provide zero nutritional value while also contributing to the development of degenerative diseases like cardiovascular disease, diabetes, obesity, and cancer. It is crucial that we avoid trans fats like the plague because they can cause damage even in small amounts. Even though a product may claim to contain “0 grams” trans fat, it may still contain small amounts that are less than .5 grams. The best way to avoid exposure is to check your ingredients labels! Trans fat will be listed on the label as “partially-hydrogenated oil”. “DATEM” and “mono-and diglycerides” are two ingredients that may contain small amounts of trans fats, so be wary of these as well.
There is a naturally occurring trans fat that has a slightly different chemical structure than that of industrially produced trans fats. This is called conjugated linoleic acid (CLA), which is formed in the bellies of grass-fed ruminants by their gut bacteria. CLA can be found in small quantities in grass-fed meat and dairy products, but don’t panic just yet! Animal and human studies suggest that CLAs may actually do wonderful things for our health, such as increase insulin sensitivity, improve cholesterol levels, and lower risks of cancer and heart disease.
So let’s review the different fats, where to find them, and which to avoid:
So, eat your healthy non-oxidized fats and avoid toxic oils like trans fats and rancid PUFAs if you’re concerned with minimizing oxidative stress and degenerative disease risks. As always, I hope you found this information useful, and feel free to leave any comments or questions in the comments section below!