The Two Essential Fatty Acids: Understanding ALA and LA

November 21, 2025 •

3 min read

Over 99% of fats in the human diet exist as triglycerides, which are composed of fatty acids. Two key polyunsaturated fatty acids, however, cannot be synthesized by the human body and must be obtained from food. These are the two essential fatty acids, alpha-linolenic acid (ALA) and linoleic acid (LA), which are critical for various physiological processes from brain function to inflammation regulation.

Quick Summary

The two essential fatty acids, alpha-linolenic acid (omega-3) and linoleic acid (omega-6), are crucial for health. Humans cannot produce them, necessitating intake through diet for cellular function, inflammation control, and brain development. Maintaining the correct balance is key for overall wellness.

Key Points

Two Essentials: The body cannot produce linoleic acid (LA) and alpha-linolenic acid (ALA), making them dietary essentials.
Omega-3 (ALA): ALA is the plant-based omega-3 essential fatty acid, converted inefficiently to EPA and DHA; sources include flaxseed and walnuts.
Omega-6 (LA): LA is the omega-6 essential fatty acid, widely found in vegetable oils and nuts; it is the precursor to pro-inflammatory signaling molecules.
Importance of Balance: An ideal ratio of omega-6 to omega-3 is crucial for managing inflammation and preventing chronic diseases, as the modern diet is often skewed heavily towards omega-6.
Key Functions: EFAs support vital bodily processes, including brain development, cardiovascular health, cell membrane structure, and immune function.
Dietary Strategy: To correct the imbalance, increase intake of omega-3 rich foods like fatty fish, flaxseed, and walnuts, while moderating consumption of highly processed foods and certain vegetable oils.

What Exactly Are Essential Fatty Acids?

Essential fatty acids (EFAs) are polyunsaturated fats the body needs for normal biological function but cannot create on its own. This necessitates dietary intake. The two primary families are omega-3 and omega-6, with alpha-linolenic acid (ALA) and linoleic acid (LA) as their respective parent compounds. Humans lack the enzymes to insert double bonds at specific positions in the fatty acid chain, making ALA and LA essential dietary components. These can be converted into other longer-chain fatty acids, though the process is often inefficient.

The Importance of the Omega-3 and Omega-6 Balance

Maintaining a balanced ratio between omega-3 and omega-6 fatty acids is crucial as they have different effects on the body. Omega-6s tend to be pro-inflammatory, while omega-3s are generally anti-inflammatory. While inflammation is necessary for healing, an imbalance with excessive omega-6 can contribute to chronic diseases. The typical Western diet often has a high ratio of omega-6 to omega-3, significantly exceeding recommended levels. This imbalance can negatively impact cardiovascular health and increase systemic inflammation.

Alpha-Linolenic Acid (ALA): The Omega-3 EFA

Alpha-linolenic acid (ALA) is the essential omega-3 fatty acid, primarily found in plant foods. It can be converted into EPA and DHA, other important omega-3s found in fatty fish, but this conversion is inefficient. {Link: Linus Pauling Institute https://lpi.oregonstate.edu/mic/other-nutrients/essential-fatty-acids} provides details on the benefits of ALA and omega-3s for cardiovascular and cognitive function, anti-inflammatory effects, and development, as well as good sources including flaxseed, chia seeds, walnuts, and some oils and vegetables.

Linoleic Acid (LA): The Omega-6 EFA

Linoleic acid (LA) is the essential omega-6 fatty acid, abundant in the modern diet, and converted into arachidonic acid (AA), involved in inflammatory signaling. A high intake relative to omega-3s is a concern. Information regarding LA's roles in cell membrane structure, energy, metabolism, immune response, and signaling molecules, as well as common sources such as vegetable oils, nuts, seeds, meat, eggs, and margarine can be found on {Link: Linus Pauling Institute https://lpi.oregonstate.edu/mic/other-nutrients/essential-fatty-acids}.

Comparison of ALA (Omega-3) and LA (Omega-6)

For a detailed comparison highlighting the differences in classification, bodily synthesis, primary roles, conversion processes, major sources, dietary balance, and the importance of their ratio between Alpha-Linolenic Acid (ALA) and Linoleic Acid (LA), please refer to {Link: Linus Pauling Institute https://lpi.oregonstate.edu/mic/other-nutrients/essential-fatty-acids}.

Optimizing Your Intake of the Essential Fatty Acids

Achieving a healthy balance involves moderating omega-6 intake while increasing omega-3 consumption. This can be done by choosing foods rich in ALA, EPA, and DHA. Algae-based supplements are an option for those who don't consume fish. Opting for oils like canola or olive oil instead of those high in omega-6 can also help. Being aware of omega-6 content in processed foods is also important. Balancing these fats supports a healthy, anti-inflammatory diet.

Conclusion

The two essential fatty acids are linoleic acid (LA) and alpha-linolenic acid (ALA). These are vital for human health, supporting cellular function, neurological health, and inflammation management as precursors for the omega-6 and omega-3 pathways. While LA is typically plentiful in modern diets, ALA is often deficient, leading to an imbalance linked to chronic health issues. Improving this ratio by incorporating more ALA-rich foods like flaxseed and walnuts, alongside sources of EPA and DHA like fatty fish or supplements, is key to obtaining proper intake and promoting well-being.

Frequently Asked Questions

Linoleic acid (LA) is an omega-6 polyunsaturated fatty acid, while alpha-linolenic acid (ALA) is an omega-3 polyunsaturated fatty acid. Both are considered essential because the human body cannot produce them and requires them from food.

The human body lacks the necessary enzymes, specifically delta-12 and delta-15 desaturase, to insert double bonds at the correct positions in the fatty acid chain, which is why we must obtain ALA and LA from our diet.

The ratio is important because omega-6 and omega-3 fatty acids have different, sometimes opposing, effects on inflammation and other bodily functions. A balanced ratio (ideally lower than the typical Western diet) helps prevent excessive inflammation associated with chronic disease.

Essential fatty acid deficiency is rare in modern diets but can lead to symptoms such as dry scaly skin, slow wound healing, and impaired growth in infants. It has also been linked to neurological issues.

Yes, ALA can be converted to the longer-chain omega-3s, EPA and DHA. However, this conversion is very inefficient, and direct intake of EPA and DHA from sources like fatty fish is recommended to ensure adequate levels.

Primary sources of ALA include flaxseed, walnuts, chia seeds, and canola oil. Rich sources of LA are vegetable oils (sunflower, corn, soybean), nuts, and seeds.

Since the conversion of ALA to EPA and DHA is inefficient, vegans and vegetarians may have lower circulating levels. They can supplement with algae-based oil to obtain pre-formed EPA and DHA.