Polyunsaturated fats: primary sources and functions in the body

Polyunsaturated fats are considered essential due to their role in health. What are its primary sources? What benefits do they bring? In this space, we will tell you about it.

Between hits and misses, fat is generally labeled a nurturing nutrient, even though polyunsaturated fats are associated with nutrition and health. Like other varieties, one single gram provides 9 kilocalories. They are a vehicle for fat-soluble vitamins. They fulfill many functions in the body.

In the sea or the crops of seeds and nuts, we find the foods that provide the most polyunsaturated fat. Also, they must be in balance with other types of fat to fulfill their nutritional and healthy functions. Do you want to know more about it? Keep reading!

What are polyunsaturated fats?

From a chemical point of view, polyunsaturated fats are fatty acids with more than one double bond between their carbon atoms, making them very unstable and active to react with other particles, such as oxygen.

Omega-3 and omega-6 fatty acids represent the most abundant structural polyunsaturated fat in mammals. They receive this name since the last terminal group of fatty acids is called omega. From here, the position of the first double bond, which appears at carbon 3 or 6, begins to be counted.

Read:4 tips to help you beat emotional eating

Coronado describes that omega-3 -alpha-linolenic (ALA) – and omega-6 -linoleic acid (LA) -, other important ones for health are formed. These fatty acid precursors are known as “essential (AGE)” because they are necessary for the body’s functioning, and the only way to acquire them is through food.

Omega-3 fatty acids

Among the six types of omega-three fatty acids, the most important is docosahexaenoic acid, also known as DHA and eicosapentaenoic or EPA, formed from ALA.

Some specialists report that the EPA regulates brain function, sight, and prostaglandins production. Also, it is easily converted into DHA. This fatty acid is part of cell membranes and the fetus’s visual development and early childhood.

There are some contradictions about the adequate amount of omega-3 to consume. Pharmacists and biologists recommend that the best consumption ratio between EPA and DHA is 4: 1. However, other studies postulate that it must be the opposite.

Omega 6 fatty acids

In this group we find linoleic acid (LA), gammalinolenic acid (GLA) and arachidonic acid (AA). They participate in the synthesis of pro-inflammatory prostaglandins and structural components of cells. They can also help control blood sugar, reduce the risk of diabetes, and lower blood pressure.

Read:What are good sources of iron for me if I on a diet?

Polyunsaturated Fat Sources

Food contains a mixture of fatty acids, saturated, monounsaturated, and polyunsaturated. In some of them, some predominate more than others. Those that have the highest proportion of polyunsaturated are shown below.

Foods that provide omega 3

The primary sources are fatty fish such as trout, salmon, herring, anchovies, albacore, and sturgeon. In the magazine Interciencia, the total values ​​of EPA and DHA are shown, in grams per 100 grams of fish, crustaceans, and mollusks.

  • Lake trout : 2.0%.
  • Dogfish : 2.0%.
  • Salmon: 1.8%.
  • Herring: 1.7%.
  • Tuna : 1.5%.
  • Anchovies: 1.4%.
  • Sturgeon: 1.5%.
  • Smooth: 1.1%.
  • Rainbow trout : 0.6%.
  • Carp : 0.6%.
  • Shrimp : between 0.3-0.5%.
  • Conch shell : 1.0%.
  • Oyster : 0.6%.
  • Short-finned squid : 0.6%.

In the same publication, the alpha-linolenic precursor or ALA values appear in vegetables, seeds, nuts, and oils.

Read:4 tips to help you beat emotional eating
  • Purslane : 4.5 milligrams / gram.
  • Quinoa : 8.35%.
  • Cooked soybeans: 2.1%.
  • Linen: 22.8%.
  • Chia : 3.9%.
  • Walnut: 6.8%.
  • Flaxseed oil: 53%.
  • Canola oil: 12%.
  • Rapeseed oil: 11%.
  • Soybean oil: 7.3%.

Foods that provide omega 6

The primary source of omega-6s is seed oils, such as sunflower, soy, and safflower. The USDA food table shows the oils with the highest proportion per 100 grams of vegetable oil.

  • Safflower oil: 74.6%.
  • Grapeseed oil: 69.9%.
  • Linseed oil: 67.9%.
  • Sunflower oil: 65.7%.
  • Poppy oil: 62.4%.
  • Soybean oil: 58.9%.

Some emulsions such as mayonnaise, non-hydrogenated margarines, and dressings made with these oils are also high in omega-6s.

Health benefits of polyunsaturated fats

The World Health Organization (WHO)  recommends using polyunsaturated fats to avoid risks of chronic diseases in the adult population. Many of these benefits are related to EPA and DHA.

Anti-inflammatory activity

Doctors Pinazo and Gomar explain that an increase in the consumption of omega-3 fatty acids increases the production of anti-inflammatory prostaglandins. Various studies reveal the effect of omega-3s on inflammatory bowel diseaserheumatoid arthritis, and asthma.

Some authors promote the frequent consumption of fatty fish as adjuvants in treating these diseases. However, more research is required to deepen these findings.

Action on the skin and anti-aging

Breiden and Sandhoff state that the skin needs essential fatty acids in situations of stress, dryness, sunburn, among others. Omega-3s restore membrane balance and produce an increase in anti-inflammatory prostaglandins.

A recent review reports the beneficial effect of these fats in stopping the chronological aging process and photoaging attributable to the sun’s UV rays and oxidative stress.

Child development

In research published in The Lancet magazine, it was observed that the children of mothers who consumed between 227 and 340 grams of fatty fish per week were healthier. The children had fewer problems with communication, behavior, and motor skills.

Fish oil supplements don’t seem to work like fatty fish. In pregnant women consuming omega-3s, there was no benefit in preventing allergies or premature birth. There was also no effect on the children’s visual or mental development.

Reduces cognitive decline during aging

The journal Nutrition Hospital concludes that omega-3 fatty acids protect against mild cognitive impairment, dementia, and the risk of Alzheimer’s disease in older adults.

For its part, the journal Neurology points out that low blood levels of DHA are associated with a smaller brain volume and cognitive impairment. A review in PloS One recognizes DHA as necessary for improving older adults’ memory.

Van Gelder and other experts also found that a moderate intake of EPA + DHA can stop cognitive decline in older adults. Despite this, other studies have found no benefit of omega-3 supplementation on Alzheimer’s disease.


The first reports on the heart-healthy properties of marine-derived Omega-3s came from the 1960s when they raised their protective role against atherosclerosis and thrombosis.

Among many investigations in this regard, a Japanese study found that the consumption of fatty fish and omega-3 supplements decreased heart failure mortality.

However, there are still contradictions. The journal JAMA Cardiology published that supplements do not decrease mortality from cardiovascular diseases.

A study in the journal Circulation found that fish oil supplements lower blood lipids. A risk factor that increases cardiovascular disease.

The American Heart Association recommends about two fish servings a week or between 300 and 500 milligrams of omega-3s a day. For their part, patients with heart disease should consume approximately 1,000 milligrams a day.

Possible risks and complications of polyunsaturated fats

Like other nutrients, polyunsaturated fats should be consumed in balanced amounts. In this way, its benefits are obtained without putting health at risk. What are your possible chances?

High caloric density

Polyunsaturated fats provide 9 kilocalories for each gram. Therefore, like any other fat, they are considered high in calories in the diet. Thus, caution must be exercised when eating foods such as fish or vegetable oils as sources of polyunsaturated fats.

Although they are considered healthy foods, they make a significant contribution of calories that will end up stored as body fat if not balanced with the other nutrients.

Pro-inflammatory fat

Omega-6 fatty acids produce several pro-inflammatory substances such as prostaglandins E2, in contrast to omega-3s, which are anti-inflammatory.

Tortosa and other experts recommend maintaining an adequate intake ratio between both types of fatty acids, consuming more omega-6 than omega-3 can promote inflammatory diseases.

According to Simopoulos, the intake ratio of omega-3 and omega-6 should be 2: 1, with a preference for EPA, DHA, and arachidonic acid.

Care in use and storage

Some researchers state that polyunsaturated fats are damaged faster than others due to their double bonds’ instability, which leads them to react with oxygen and form some undesirable compounds.

For this reason, they should be stored in a cool place with little light before opening the package. Once uncovered, they must be kept refrigerated. Zárate and other experts comment that heat produces harmful substances in these fats, related to neurodegenerative diseases in laboratory animals.

Polyunsaturated fatty acids are part of a healthy diet. Like any nutrient, they should be consumed in moderation and balance, especially omega-3 and omega-6. If you have doubts about the amounts of consumption that correspond to you, consult a health or nutrition specialist.



    • Kozlowska, A., & Szostak-Wegierek, D. (2014). Flavonoids-food sources and health benefits. Roczniki Państwowego Zakładu Higieny ,  65 (2).
    • Pohl F., Lin PK., The potential use of natural plant products and plant extracts with antioxidant properties for the prevention/treatment of neurodegenerative diseases: in vitro, in vivo and clinical trials. Molecules, 2018. 23 (12): 3283.
    • Carr AC., Maggini S., Vitamin C, and immune function. Nutrients, 2017. 9 (11): 1211
    • Zavala Naranjo Carlos Iván. Uso de omega 3 como tratamiento antienvejecimiento. Medisur. 2020 , 18( 6 ): 1198-1209.
    • Valenzuela B Rodrigo, Tapia O Gladys, González E Marcela, Valenzuela B Alfonso. ÁCIDOS GRASOS OMEGA-3 (EPA Y DHA) Y SU APLICACIÓN EN DIVERSAS SITUACIONES CLÍNICAS. Rev. chil. nutr. 2011 , 38( 3 ): 356-367. Disponible en:
    • Castellanos T Lyssia, Rodriguez D Mauricio. El efecto de omega 3 en la salud humana y consideraciones en la ingesta. Rev. chil. nutr. 2015 ; 42( 1 ): 90-95. Disponible en:
    • Castro, María Isabel. Ácidos grasos omega 3: beneficios y fuentes. Interciencia. 2002. vol. 27, (3), pp. 128-136.
    • Silvia Berciano, S. y Ordovás, J. Nutrición y Salud Cardiovascular. Revista Española de Cardiología. 2014, 67,9, 738-747.
    • Aires, D., Capdevila, N., Segundo, M. Ácidos grasos esenciales. Su influencia en las diferentes etapas de la vida. Ámbito Farmacéutico. Divulgación sanitaria. 2005, 24 (4),97-102.
    • Vieira, S. A., McClements, D. J., & Decker, E. A. (2015). Challenges of utilizing healthy fats in foods. Advances in nutrition (Bethesda, Md.)6(3), 309S–17S.
    • Aung, T., Halsey, J., Kromhout, D., Gerstein, H. C., Marchioli, R., Tavazzi, L., Geleijnse, J. M., Rauch, B., Ness, A., Galan, P., Chew, E. Y., Bosch, J., Collins, R., Lewington, S., Armitage, J., Clarke, R., & Omega-3 Treatment Trialists’ Collaboration (2018). Associations of Omega-3 Fatty Acid Supplement Use With Cardiovascular Disease Risks: Meta-analysis of 10 Trials Involving 77 917 Individuals. JAMA cardiology3(3), 225–234

Previous post
What are antioxidants, and what are they used for?
Next post
What are the types of fibers that most help the microbiota?

One thought

Add yours

  1. Pingback: White and red meat affect cholesterol in the same way, according to studies | faceknow

Leave a Reply