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Are Polyunsaturated Fats Good or Bad? Everything You Need to Know

Are polyunsaturated fats good or bad for you?

I have always been a big fan of consuming foods that are healthy and one of the best ways to do that is by eating unsaturated fats and balancing with fruits and veggies. The problem with eating saturated fats is that they clog in your arteries causing heart problems, but you can avoid that by only eating unsaturated fats.

Unsaturated fats are those that contain one or more double bonds in their molecular structure, known as polyunsaturated fats. They can lower bad cholesterol, prevent atherosclerosis and increase the life span.

In this article, we will cover polyunsaturated fats, the omega-3 and omega-6 PUFAs, their health benefits, the good and bad sides.

What are Polyunsaturated Fats?

Polyunsaturated fats are fatty acids with more than one unsaturation in their molecules and due to this feature they have the potential to be beneficial to health.

In polyunsaturated fatty acids the first double bond may be found between the 3rd and 4th carbon atom, these are called omega-3 fatty acids. If the first double bond is between the 6th and 7th carbon atom, then they are called omega-6 fatty acids. The double bonds in PUFAs are separated from each other by a methylene group.

There are two types of PUFAs, they include:

  • linolenic acid – also known as omega-3 is found in canola, soybean, nuts, seeds, salmon, mackerel..etc
  • linoleic acid – Is called omega-6, sources are found in vegetable oils and meat

Read: 9 Best sources of polyunsaturated fats that are heart healthy

Omega-3 and Omega-6 fatty acids benefits:

  • Essential for normal growth and development
  • Prevents heart disease, hypertension, arthritis and cancer
  • Used to make “eicosanoids” biologically active compounds
  • Help lower blood pressure
  • Prevent clot formation
  • Protect against irregular heartbeats
  • Reduce inflammation
  • Good for the eyes and brain

Why You Should Eat Polyunsaturated Fats

The American Heart Association has recommended that healthy adults should eat at least two servings of oily fish per week to boost omega-3 PUFAs intake. Eating 2 to 4 ounces will generally provide about 1 gram of omega-3 fatty acids.

Additionally, AHA suggested that people should get at least 5% to 10% of calories from omega-6 fatty acids in combination with other AHA lifestyle and dietary guidelines.

Recently, there has been controversies over whether the consumption of omega-6 are associated with increased risk of coronary heart disease and cardiovascular disease.

However, research has demonstrated that consuming at least 5% to 10% of energy from omega-6 PUFAs may decrease the risk of coronary heart deaths compared to lower intakes.

The DRI Report and the 2005 Dietary Guidelines for Americans support the 5% to 10% of dietary energy from omega-6 fatty acids as an acceptable macronutrient distribution range.

Polyunsaturated Fats are Better Than Saturated Fats

The increased consumption of saturated fats are linked to heart diseases which is the leading cause of death. The dietary guidelines for americans recommends the intake of 200g of fish per week, that is, about 250mg of EPA and DHA shows evidence of heart disease prevention.

According to the recommendations of the food and agriculture organization, there is compelling evidence that saturated fatty acids lead to increased LDL and HDL cholesterol ratio compared with MUFAs.

Still, saturated fatty acids increase LDL cholesterol, however, they have no effect on the total cholesterol ratio compared with carbohydrates.

Another evidence also shows that high plasma levels of PUFAs are associated with the decrease in the total cholesterol ratio, and that the replacement of 10% calories from saturated fatty acids with omega-6 is associated with a reduction of 18 mg/dL in LDL cholesterol.

Consuming 10% of PUFAs is related to low risk of cardiovascular diseases, and the replacement of 1% calories from saturated fatty acids with PUFAs reduces to 3% the risk of cardiovascular events.

The Downside of Polyunsaturated Fats

Plant oils and fish are known as major sources of omega-3 and omega-6 PUFAs. Soybean oil and canola oil are rich in alpha-linolenic acid, while some fatty fish including salmon, sardine, and menhaden contain abundant EPA and DHA.

Though PUFAs are healthy for human consumption, there are downsides as well. Polyunsaturated fats are prone to oxidation, and thus can negatively affect both food quality and human health.

PUFAs oxidation on food quality:

  • Lipid oxidation – PUFA-rich foods are more susceptible to oxidation. Lipid oxidation often brings problems in food processing and storage. It negatively affects food flavor due to the formation of aldehydes and ketones. Oxidation of PUFAs produces a complex mixture of volatile secondary oxidation products, and these cause unpleasant off-flavors. For example, soybean oil can undergo flavor reversion, a type of light-induced oxidation.
  • Reduces nutritional value – Lipid oxidation can damage essential fatty acids and lipid soluble vitamins A, D, E, and K as well as decrease in caloric content.

PUFAs oxidation on human health:

  • HNE, a product from omega-6 oxidation of PUFAs, has been found in atherosclerosis, neurode-generative diseases and cancer.
  • Oxidized PUFAs rich in HNE and HHE induces oxidative stress and inflammation in human intestinal cells.


Polyunsaturated fats are good for you, it is important to include them in your diet. One of the best sources of PUFAs are oily fish and fish oil supplements. Consumption should be in low amounts, well balanced with low-carb diets, and vegetables. Polyunsaturated fats are heart healthy but too much of it can raise cholesterol levels leading to weight gain, coronary risks and oxidative stress.

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