What is Polyunsaturated Fat?
A polyunsaturated fat is a fatty acid, commonly found in many plant foods, which contains 2 or more double bonds in it (of the carbon atoms).
First, to fully understand and appreciate a polyunsaturated fat, let us just quickly go over what a saturated fat is. A saturated fat is a fatty acid chain whose carbon atoms are completely saturated with hydrogen. This means that every carbon atom in the fatty acid chain (with the exception of the carboxyl group of the molecule) contains a single bond with a hydrogen atom. This means it's completely saturated with hydrogen.
Take a look at the saturated fat, butyric acid, below, which is the acid which gives butter its flavor.
You can see above that every carbon atom is linked to a single hydrogen atom. In this way, it is saturated.
Now let's go back to polyunsaturated fats. Instead of every single carbon atom being linked with a single bond to a hydrogen atom, 2 or more of the single bonds is replaced with a double bond.
Below is an example of a polyunsaturated fat, called linoleic acid, to illustrate this point:
You can see how the double bond removes the need for 4 hydrogen atoms. Therefore, the fatty acid is no longer saturated with hydrogen atoms, as the above saturated fat was. This is why it is called an unsaturated fat. Poly (standing for many) means it has more than one double bond.
As you could see above, hydrogen atoms are eliminated where double bonds are formed. The body adds hydrogen, a process that saturates the fat. In other words, the unsaturated fat molecule is malleable and is subject to change within the body. The body can work with it and utilize it. It then integrates these self-manufactured saturated fats into our bodily structure as needed. This is why unsaturated fats are better for our bodies.
When compared to monunsaturated fat, polyunsaturated fatty acids are the least saturated, with room for two or more pairs of hydrogen atoms. Polyunsaturated oils have even lower melting points, meaning they are all liquid at room temperature.
Sources of Polyunsaturated Fat
Unsaturated fatty acids make up the bulk of plant fats. Whole-food raw plants sources of polyunsaturated fat include green leafty vegetables, and walnuts and other nuts and seeds and their butters.
Even though polyunsaturated fat is a healthier form of fat than its saturated counterpart, fat is still fat and should be kept low in our diet.
Whether it's healthy fat or bad fat, whether it's monounsaturated, polyunsaturated, or saturated fat, it should still be kept a low limit in our overall calories
which are consumed. Common health advisory is to keep fat to only 10% of calories consumed. And of that 10% of fat which is consumed, keep the S/P ratio (saturated
fat to polyunsaturated fat) to a 20/80 ratio, meaning of the fat consumed, make sure that 20% or less is saturated and 80% or more is mono or polyunsaturated.