What is linoleic acid and alpha linolenic acid?

November 21, 2025 •

4 min read

An estimated 80% of Americans have a diet with an imbalanced ratio of omega-6 to omega-3 fatty acids. Understanding the difference between linoleic acid and alpha linolenic acid, the key essential fats, is vital for improving overall health and correcting this imbalance.

Quick Summary

Linoleic acid (omega-6) and alpha linolenic acid (omega-3) are essential polyunsaturated fatty acids derived from food. They play crucial roles in cell structure and metabolic functions, with a balanced intake being important for health.

Key Points

Essential Nutrients: Both linoleic acid (LA) and alpha linolenic acid (ALA) are essential fatty acids that the human body cannot produce and must be obtained through diet.
Omega-6 vs. Omega-3: LA is the parent omega-6 fatty acid, while ALA is the parent omega-3. They are metabolized by the same enzymes and compete with each other.
Diverse Functions: LA is critical for maintaining skin barrier function, while ALA and its derivatives (EPA and DHA) are vital for heart and brain health.
Pro- vs. Anti-Inflammatory: Omega-6 metabolites from LA are often pro-inflammatory, whereas omega-3 metabolites from ALA are generally anti-inflammatory, highlighting the need for balance.
Metabolic Conversion: The body’s conversion of ALA to the potent long-chain omega-3s (EPA and DHA) is very inefficient, emphasizing the need for direct intake from sources like fatty fish or supplements.
Dietary Imbalance: The modern Western diet is often skewed with an excess of omega-6 fatty acids, potentially contributing to chronic inflammation.
Correcting Intake: To correct the imbalance, one should increase consumption of ALA-rich foods like flaxseed and walnuts while moderating intake of high-omega-6 vegetable oils.

What are Essential Fatty Acids?

Essential fatty acids (EFAs) are a type of polyunsaturated fat that the human body requires but cannot synthesize on its own. As a result, they must be obtained through diet. EFAs serve as the building blocks for more complex fatty acids and play vital roles in cellular metabolism, inflammation, and hormone production. There are two main families of EFAs: the omega-6 fatty acids and the omega-3 fatty acids.

What is Linoleic Acid (Omega-6)?

Linoleic acid (LA) is the primary omega-6 essential fatty acid, denoted as C18:2n-6. After being consumed, LA can be converted through a series of metabolic steps into other omega-6 fatty acids, including arachidonic acid (AA).

Key Functions of Linoleic Acid

LA and its derivatives are involved in several physiological processes, some of which are often perceived as pro-inflammatory. However, it is a crucial nutrient for the following functions:

Skin barrier function: LA is a critical component of ceramides in the epidermis, maintaining the skin's water permeability barrier. Deficiency can lead to a dry, scaly rash.
Lipid regulation: Research shows that higher dietary LA intake can lower total and LDL cholesterol when replacing saturated fats, thus improving cardiometabolic health.
Energy and cell structure: As an EFA, it is integrated into cell membranes and provides energy for the body.

Sources of Linoleic Acid

LA is abundant in many vegetable oils and seeds, including:

Safflower oil
Sunflower oil
Corn oil
Soybean oil
Nuts (e.g., walnuts)

What is Alpha-Linolenic Acid (Omega-3)?

Alpha-linolenic acid (ALA) is the essential omega-3 fatty acid, designated as C18:3n-3. While ALA is essential, its conversion to longer-chain omega-3s—eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)—is quite limited in humans.

Key Functions of Alpha-Linolenic Acid

ALA and its longer-chain derivatives, EPA and DHA, offer a range of health benefits, often acting as anti-inflammatory agents in the body. Its functions include:

Cardiovascular health: ALA is associated with a reduced risk of heart disease, helping maintain normal heart rhythm, and potentially lowering blood pressure.
Brain health: Especially through its conversion to DHA, ALA plays a vital role in neurological and cognitive functions. It supports neurogenesis and protects against neuronal cell death.
Anti-inflammatory effects: As a precursor to anti-inflammatory eicosanoids, ALA helps balance the pro-inflammatory effects of omega-6 fatty acid metabolism.

Sources of Alpha-Linolenic Acid

ALA is found primarily in plant-based sources, including:

Flaxseed and flaxseed oil
Chia seeds
Walnuts
Canola oil
Soybean oil

Linoleic Acid vs. Alpha Linolenic Acid: A Comparison


Feature	Linoleic Acid (LA)	Alpha-Linolenic Acid (ALA)
Fatty Acid Family	Omega-6 (n-6)	Omega-3 (n-3)
Chemical Notation	C18:2n-6	C18:3n-3
Primary Role	Skin barrier, pro-inflammatory signaling (metabolites)	Anti-inflammatory signaling, nervous system development
Metabolic Pathway	Converts to arachidonic acid (AA)	Converts inefficiently to EPA and DHA
Main Food Sources	Corn oil, safflower oil, sunflower oil	Flaxseed oil, chia seeds, walnuts, canola oil
Inflammatory Effect	Can promote inflammation via eicosanoids	Can reduce inflammation via eicosanoids
Ideal Intake	Moderated, balanced with ALA	Increased to correct modern dietary imbalances

The Importance of Dietary Balance

While both linoleic acid and alpha linolenic acid are essential, the balance between them is crucial for health. The enzymes that process omega-6 and omega-3 fatty acids are the same, leading to competition. The typical Western diet often contains a significantly higher ratio of omega-6 to omega-3, sometimes as high as 10:1 or even 20:1. An unbalanced ratio, with excess omega-6, can lead to a physiological state that is more pro-inflammatory. Balancing this ratio by increasing ALA intake relative to LA is linked to better health outcomes, including improved cardiovascular and neurological health.

Correcting this imbalance can involve conscious dietary choices. For example, reducing consumption of processed foods that use high-omega-6 vegetable oils and increasing intake of omega-3-rich foods can help shift the balance towards a healthier ratio. For more information on the critical role of these essential fatty acids, see the resource on essential fatty acids from the Linus Pauling Institute.

Conclusion

Linoleic acid (omega-6) and alpha linolenic acid (omega-3) are two distinct but equally vital essential fatty acids. Though both are necessary for human health, they play different physiological roles, with LA largely influencing skin integrity and some inflammatory responses, while ALA is a precursor for anti-inflammatory compounds and critical for brain and heart function. Maintaining a proper dietary balance between these two fats is a cornerstone of modern nutrition science, with imbalances linked to chronic disease. By consuming a variety of healthy plant and animal sources, individuals can ensure they receive adequate amounts of both and support optimal health.

Frequently Asked Questions

Linoleic acid (LA) is an omega-6 fatty acid, primarily found in vegetable oils and seeds, and plays a role in skin health. Alpha linolenic acid (ALA) is an omega-3 fatty acid, found in flaxseed, walnuts, and chia seeds, and is crucial for heart and brain health.

They are called 'essential' because the human body cannot produce these fatty acids on its own. They must be consumed through the diet to maintain proper physiological function, cellular metabolism, and tissue health.

Linoleic acid is important for maintaining the skin's water-permeability barrier and for normal growth. When replacing saturated fats, it has been shown to lower total and LDL cholesterol, contributing to cardiometabolic health.

ALA is associated with a reduced risk of coronary heart disease, helping maintain normal heart rhythm, and potentially lowering blood pressure. It is also a precursor to longer-chain fatty acids important for brain health and anti-inflammatory effects.

Linoleic acid is found in high concentrations in vegetable oils such as corn, safflower, sunflower, and soybean oils. It is also present in nuts, seeds, meat, and eggs.

Rich plant-based sources of ALA include flaxseed, chia seeds, walnuts, and plant oils such as flaxseed, canola, and soybean oil. Green leafy vegetables also contain ALA.

It is not about consuming more of one, but achieving a healthy balance between the two. The modern Western diet often contains too much omega-6. It is generally recommended to increase omega-3 intake to balance the ratio and reduce potential inflammatory effects.

Yes, the body can convert ALA into the longer-chain omega-3 fatty acids EPA and DHA, but this conversion is very inefficient. This is why it's recommended to consume EPA and DHA directly from foods like fatty fish or supplements.