Fats come in many different chemical forms, including monounsaturated fats and polyunsaturated fats. Though all fats supply nine calories, some are still considered more healthy than others. One of those healthy fats in polyunsaturated fat.

What is Polyunsaturated Fat?

First let's understand what a fat molecule is. On a microscopic level, a fat molecule is a chain of carbon atoms. On each little link of this chain, there is attached a hydrogen atom. If every chain link holds a hydrogen, it is a saturated fat, the kind you are often told to avoid. These fats, like butter and lard, are solid at room temperature.

If some of the links are missing their hydrogen, and instead have a double-bonded carbon, they are unsaturated, that is, not packed full of hydrogen. These fats are liquid at room temperature, such as oil. If the have only one double bond, they are monounsaturated. If they have more than one double bond, they are polyunsaturated.

Are Polyunsaturated Fats Healthy?

There is a great deal of evidence touting both the positive and negative attributes of polyunsaturated fats. In general, both kinds of unsaturated fats are preferable to saturated fats. This is because unlike saturated fats, unsaturated ones do not bond together to form plaque in your bloodstream.

Of the two unsaturated, polyunsaturated is considered slightly less healthy than monounsaturated. Although there is evidence linking polyunsaturated to increased heart health, the unstable nature of multiple double bonds and the tendency toward quick oxidation leads to increased rancidity. There are studies suggesting links between this rapid rotting and diabetes, cataracts, premature aging and possibly cancer.

The Benefits

However, if kept fresh, polyunsaturated fats can provide many health benefits. They have little cholesterol and can decrease heart disease risk if eaten in place of saturated fats. They also carry essential fats that your body cannot produce but must consume, such as fatty acids omega-6 and the DHA-containing omega-3.

The Foods

Although most foods contain a combination of different kinds of fats, some foods are higher in polyunsaturated fats than others. These include oils such as vegetable oils, including soybean oil, corn oil and safflower oil. They are also found in healthy foods such as fatty fish (salmon, mackerel, herring and trout) and some nuts and seeds.

Again, it is important to eat these foods while they are fresh to benefit wholly from their polyunsaturated fats. Eating them fresh also reduces the likelihood of any negative effects due to oxidation.

Calories from fat should make up no more than 30 percent of your daily intake. It is recommended that the majority of that fat comes from an unsaturated source. Current research shows that fresh polyunsaturated fats are a healthy way to consume necessary fats.