Mono and Polyunsaturated Fat Explained
Let’s take a few minutes to explain mono and polyunsaturated fats and what I think you should know about them. They are one of the 3 major types of dietary fat that you should understand, so I’m going to take a few minutes to explain what they are and how they can affect your health.
The first thing I want to talk about is structure, since that is important to understand how it’s different from saturated fatty acids and unsaturated fatty acids. In this picture you are looking at saturated fatty acid and unsaturated fatty acid. Fatty acids contain a long tail and this tail is composed of carbon and hydrogen atoms. At the head of any fatty acid is what’s called a carboxyl group. They are the same on all fatty acids so I won’t spend any more time talking about them, because they don’t define the distinction between the different fatty acids or types of fat.
What makes this an unsaturated fatty acid are the carbon-carbon double bonds. This is depicted by the red arrows. Each black line represents a bond between two atoms, so when you see two, it represents two double bonds between two atoms. The bottom fatty acid is a monounsaturated fatty acid because it has one carbon-carbon double bond. A polyunsaturated fatty acid simply has more than 1 double bond.
Polyunsaturated fats are also a blanket term that encompases many types of fat you may have heard of before. This includes all types of omega-3 fatty acids (alpha linoleic acid, Eicosapentaenoic acid, and Docosahexaenoic acid) as well as omega-6 and and omega-9 fatty acids. Categorically, there are many more known types of fatty acids that fall under this umbrella, but it important that you appreciate that omega-3, omega-6 and omega-9 fatty acids are types of polyunsaturated fatty acids.
Now technically, trans fatty acids are unsaturated, which you can see in this picture. They have a carbon-carbon double bond. What makes them different is the way that the double bond bends the architecture of the fatty acid. Polyunsaturated fatty acids have a “cis” configuration where the double bond bends away from itself. You can see that each double bond forms a “C” type formation and thats because the adjacent atoms are bending away from the double bond. In the trans fatty acid, they bend towards each other, which is why you get a “Z” type formation. This distinction is important because it completely changes the way your body is able to metabolize the fat.
Monounsaturated Fatty Acids
There is no consensus on recommendations for the consumption of monounsaturated fatty acids in the diet. However, when compared to trans fats or saturated fats, they appear to have positive effects on blood lipid levels. Monounsaturated fats are most beneficial when they replace saturated and trans fats in your diet and when consumed in moderation. They may decrease LDL cholesterol (the bad one) and triglycerides, and raise HDL cholesterol (the good one). Some studies have linked monounsaturated fat to a reduction in risk of heart disease and stroke. It has also been linked to reduced insulin resistance in type 2 diabetics. Monounsaturated fats are often high in vitamin E, which is an antioxidant.
Polyunsaturated Fatty Acids
Polyunsaturated fatty acids are essential nutrients in humans. This means you don’t synthesize them yourself and must get them from food sources. They provide numerous health benefits. As with monounsaturated, the effect of polyunsaturated fatty acids is most prominent when they are used to replace trans and saturated fatty acid and consumed in moderation.
They have been shown to lower LDL cholesterol, triglycerides and raise HDL cholesterol. They have been linked to a reduction in coronary heart disease. Although the evidence from clinical trials is somewhat mixed, there appears to be a reduction in heart disease in populations with diets high in polyunsaturated fatty acids. They have been linked to a reduction in stroke risk, although again, the evidence is mixed. It has been linked with a reduced risk of developing type 2 diabetes and alzheimer disease.
Best Dietary Sources
Begetable oils (olive, canola, peanut, sunflower and sesame), many fatty fish (salmon, mackerel, herring, trout), and many nuts and seeds (eg, walnuts, sunflower seeds)
The American Heart Association recommends between 25 and 35% of your total daily caloric intake be composed of mono- and polyunsaturated fatty acids. When possible, these should be used to replace trans and saturated fatty acids.