What do essential fatty acids include? A comprehensive guide to EFAs

December 29, 2025 •

4 min read

The human body cannot produce essential fatty acids (EFAs) on its own, making them a vital part of a balanced diet for overall health. These polyunsaturated fats are critical for numerous bodily functions, from cellular metabolism to brain health and inflammation control, and must be sourced from foods or supplements.

Quick Summary

Essential fatty acids consist of omega-3 and omega-6 families, specifically alpha-linolenic acid (ALA) and linoleic acid (LA). They are vital for human health and must be obtained through dietary sources like fish, nuts, and seeds.

Key Points

Two Primary Families: Essential fatty acids (EFAs) include omega-3 and omega-6 families, with parent compounds alpha-linolenic acid (ALA) and linoleic acid (LA) respectively.
Body Cannot Produce Them: Humans must obtain EFAs through diet because the body lacks the specific enzymes needed for their synthesis.
Omega-3s for Anti-inflammatory Effects: The most beneficial omega-3s, EPA and DHA, found in fatty fish, help reduce inflammation and support brain and heart health.
Omega-6s for Cell Function: Omega-6s, primarily LA from vegetable oils, provide energy and are crucial for skin barrier function.
Balance is Crucial: A high ratio of omega-6 to omega-3, common in Western diets, can increase inflammatory responses; maintaining a better balance is key for health.
Rich Dietary Sources: EFAs can be found in fatty fish, flaxseed, chia seeds, walnuts, and various vegetable oils, with plant-based sources providing ALA.

Understanding the Two Families of Essential Fatty Acids

Essential fatty acids (EFAs) are polyunsaturated fats categorized into two main families: the omega-3s and the omega-6s. The defining characteristic is the location of the first double bond in their chemical structure, counting from the methyl end. Since the human body lacks the necessary enzymes (delta-12 and delta-15 desaturases) to create these double bonds in the correct positions, it cannot synthesize these crucial fats from scratch.

The Omega-3 Fatty Acids

The omega-3 family begins with its parent compound, alpha-linolenic acid (ALA). While ALA is essential and found in plants, the human body can convert it into longer-chain omega-3s, but this process is inefficient. Therefore, obtaining the more active forms directly from the diet is highly beneficial. The key omega-3s include:

Alpha-linolenic acid (ALA): The primary plant-based omega-3. The body uses ALA for energy and as a precursor for other omega-3s.
- Sources: Flaxseed, flaxseed oil, chia seeds, walnuts, canola oil, and soybeans.
Eicosapentaenoic acid (EPA): Found predominantly in marine sources, EPA is known for its role in producing eicosanoids that help reduce inflammation.
- Sources: Fatty fish like salmon, mackerel, and herring, as well as algal oil.
Docosahexaenoic acid (DHA): Also primarily from marine life, DHA is a major structural component of the brain and retina.
- Sources: Fatty fish, fish oil supplements, and algal oil.

The Omega-6 Fatty Acids

The omega-6 family starts with its parent compound, linoleic acid (LA). Like ALA, LA is essential and serves as a precursor for longer-chain derivatives. The typical Western diet provides an abundance of omega-6s, often leading to an imbalanced ratio with omega-3s. Key omega-6s are:

Linoleic acid (LA): The most common omega-6 fatty acid. The body can convert it to other longer-chain omega-6s.
- Sources: Soybean oil, corn oil, sunflower oil, nuts, and seeds.
Gamma-linolenic acid (GLA): A derivative of LA found in certain plant oils.
- Sources: Evening primrose oil and borage oil.
Arachidonic acid (AA): Produced from LA, AA is an important precursor for signaling molecules, some of which are pro-inflammatory.
- Sources: Meat, poultry, and eggs.

Functions of Essential Fatty Acids

Both omega-3 and omega-6 fatty acids are crucial for health, playing distinct but interconnected roles.

Cellular Structure: EFAs are critical components of cell membranes throughout the body, influencing their fluidity, flexibility, and overall function. High DHA levels are particularly concentrated in brain and retinal cells.
Inflammation Regulation: EFAs produce hormone-like signaling molecules called eicosanoids. Omega-6-derived eicosanoids tend to be more pro-inflammatory, while omega-3-derived eicosanoids are generally less inflammatory or anti-inflammatory. A balanced ratio is key for modulating the body's inflammatory response.
Brain and Nervous System: DHA is vital for brain development, cognitive function, and memory. EFAs also support proper nerve signaling.
Cardiovascular Health: Omega-3s, especially EPA and DHA, have documented benefits for heart health, including lowering triglycerides, reducing arrhythmia risk, and improving vascular function.
Skin and Hair Health: Linoleic acid (omega-6) is essential for maintaining the skin's water barrier. Deficiency can lead to dry, scaly skin.
Hormone Production: EFAs are precursors for hormones that regulate blood pressure, blood clotting, and fertility.

Deficiency and the Importance of Balance

While severe EFA deficiency is rare, the average Western diet often has an imbalanced ratio, typically far too high in omega-6 relative to omega-3. A high omega-6 to omega-3 ratio is linked to increased inflammation, while a more balanced intake supports overall health. Symptoms of EFA deficiency can include skin rashes, hair loss, fatigue, and impaired growth.

Omega-3 vs. Omega-6 Fatty Acids


Feature	Omega-3 (ALA, EPA, DHA)	Omega-6 (LA, GLA, AA)
Classification	Polyunsaturated fatty acids with the first double bond at the third carbon from the methyl end.	Polyunsaturated fatty acids with the first double bond at the sixth carbon from the methyl end.
Dietary Sources	Plant-based: Flaxseed, chia seeds, walnuts. Marine-based: Fatty fish (salmon, mackerel), algal oil.	Vegetable oils (soybean, corn, sunflower), nuts, seeds, poultry, eggs.
Primary Function	Anti-inflammatory response modulation, brain and retinal development, cardiovascular support.	Energy provision, cell structure, essential for skin barrier function.
Derivative Examples	Eicosapentaenoic Acid (EPA), Docosahexaenoic Acid (DHA).	Gamma-linolenic Acid (GLA), Arachidonic Acid (AA).
Typical Ratio in Diet	Often low in the Western diet, leading to an imbalance.	High in the Western diet, contributing to a skewed ratio.

Dietary Strategies for an Optimal EFA Balance

To achieve a healthier balance, focus on increasing your omega-3 intake while maintaining a moderate omega-6 intake. This can be achieved by incorporating a variety of foods into your diet. For non-meat eaters, plant-based sources of ALA are essential, although supplementation with algal oil for direct EPA and DHA can be necessary due to poor conversion efficiency.

One authoritative source for further reading is the Linus Pauling Institute's Micronutrient Information Center on Essential Fatty Acids.

Conclusion: Making Informed Dietary Choices

Essential fatty acids are not just another nutrient; they are foundational to human health, influencing everything from cell function to inflammation and brain development. The body's inability to synthesize them underscores the critical importance of diet. By understanding that EFAs include both the omega-3 and omega-6 families, and being mindful of your intake sources, you can actively work towards a balanced nutritional profile. Prioritizing foods rich in omega-3s, while consuming omega-6s in moderation, can help mitigate potential inflammatory effects and support long-term wellness. Ultimately, a varied and thoughtful diet is the best way to ensure your body receives these vital building blocks for optimal health.

Frequently Asked Questions

The main difference is their chemical structure, specifically the position of the first double bond. Omega-3s have the double bond at the third carbon from the methyl end, while omega-6s have it at the sixth carbon. This structural difference leads to varying roles in the body's inflammatory response.

The body can convert ALA into EPA and DHA, but the conversion efficiency is very low, especially for DHA. Therefore, consuming direct sources of EPA and DHA, such as fatty fish or algal oil, is the most effective way to increase their levels.

For omega-3s, good sources include fatty fish (salmon, mackerel), flaxseed, chia seeds, and walnuts. For omega-6s, excellent sources include vegetable oils like soybean, corn, and sunflower, as well as nuts and seeds.

Although rare, deficiency can lead to several symptoms, including dry, scaly skin and rashes, fatigue, impaired growth, and increased susceptibility to infections.

Both omega-6 and omega-3 are precursors for signaling molecules that regulate inflammation. Omega-6-derived molecules are more pro-inflammatory, while omega-3-derived ones are often anti-inflammatory. An imbalanced ratio, common in modern diets, can contribute to chronic inflammation.

The need for supplements depends on your dietary habits. If you don't regularly consume sufficient sources of omega-3s, like fatty fish, a supplement may be beneficial. For vegans or those who avoid fish, algal oil supplements provide direct EPA and DHA.

Yes, linoleic acid (LA) is the parent omega-6. The body can convert it into other omega-6s, such as gamma-linolenic acid (GLA) and arachidonic acid (AA), which serve various functions within the body.