What is the richest plant source of arachidonic acid?

November 12, 2025 •

3 min read

In a 2002 study published in Phytochemistry, the green oleaginous alga, Parietochloris incisa, was identified as the richest plant source of arachidonic acid (AA), accumulating up to 47% of its total fatty acids as AA. This discovery contradicts the common misconception that this essential omega-6 fatty acid is found exclusively in animal products.

Quick Summary

The richest plant source of arachidonic acid is the green microalga Parietochloris incisa. Unlike higher plants, some algae and lower plant forms naturally produce significant amounts of this omega-6 fatty acid, which is vital for human health.

Key Points

Richest Plant Source: The green microalga Parietochloris incisa has been identified as the most concentrated plant source of arachidonic acid (AA), accumulating up to 47% of its total fatty acids as AA.
Higher Plants Lack AA: Most common terrestrial plants and vegetables, such as soybeans and spinach, contain virtually no preformed AA due to lacking the necessary metabolic pathways.
Body Can Synthesize AA: The human body can synthesize AA from linoleic acid (an omega-6 fatty acid found in nuts, seeds, and vegetable oils), but the conversion rate can be low.
Other Plant-Based Sources: Aside from Parietochloris incisa, some mosses, lichens, and other microalgae also contain small to moderate amounts of AA.
Importance of AA: Arachidonic acid is crucial for brain development, cell membrane structure, muscle growth, and regulating the immune system.
Microbial Production: Because of the scarcity of AA in higher plants, industrial production for supplements often relies on fermenting microbes like the fungus Mortierella alpina.
Dietary Considerations: Vegans and vegetarians have lower dietary intake of AA, though for healthy adults, endogenous synthesis is generally sufficient. Infants, however, rely on breast milk or AA-fortified formula.

What is Arachidonic Acid (AA)?

Arachidonic acid (AA), a polyunsaturated omega-6 fatty acid (20:4ω-6), is a critical component of cell membranes in the human body. It is especially abundant in the brain, muscles, and liver, contributing to cell signaling, immunity, and inflammatory responses. While the body can synthesize some AA from the essential fatty acid linoleic acid, direct dietary intake is also a significant factor, especially during infancy. Historically, animal products like meat, eggs, and dairy were considered the primary dietary sources, leading to questions about AA intake for those on plant-based diets.

The Richest Plant Source Revealed: Parietochloris incisa

Contrary to popular belief, higher terrestrial plants contain virtually no preformed AA. The groundbreaking discovery of Parietochloris incisa as a rich plant source came from researching algae in alpine environments. This green microalga was found to be exceptionally rich in AA, storing it in high concentrations within its triacylglycerol lipids. The alga's ability to produce high levels of AA has made it a subject of pharmaceutical and nutritional interest, and its lipids have been studied for potential use in supplements.

Other Notable Plant Sources

While Parietochloris incisa is a standout, other plant forms also contain varying levels of AA, although typically much lower. These include mosses and other types of microalgae. This list provides some known examples:

Mosses: Certain moss species, such as Physcomitrella patens and Marchantia polymorpha, have been found to contain AA, often as part of their unique lipid compositions.
Other Microalgae: Several red and green microalgae, including Myrmecia incisa and Porphyridium cruentum, have shown significant AA accumulation under specific environmental conditions.
Lichens: Some lichen species, which are a symbiotic association between algae and fungi, contain detectable amounts of AA, though the levels can vary depending on the species and growth conditions.
Artemisia Plants: A study on certain Artemisia species detected AA, though it is hypothesized to originate from fungal endophytes living within the plants.

Why Higher Plants Don't Produce Significant AA

The reason higher plants do not contain substantial levels of AA is due to genetic differences and distinct metabolic pathways. The biochemical synthesis of AA from linoleic acid requires specific enzymes (desaturases and elongases) that are either absent or less active in most terrestrial plants. In contrast, certain algae and fungi possess the necessary enzymatic machinery to produce this long-chain polyunsaturated fatty acid. Genetic engineering research has explored introducing these genes into oilseed plants to create new plant-based sources of AA, but these are not naturally occurring.

Comparison: Arachidonic Acid in Different Plant Sources


Source Type	Examples	Typical AA Content	Notes
Microalgae (Richest)	Parietochloris incisa	Up to 47% of total fatty acids	Content can be optimized by nutrient starvation.
Mosses	Physcomitrella patens, Marchantia polymorpha	Detectable, but lower than P. incisa	Contains the necessary genes for AA synthesis.
Lichens	Peltigera canina, Leptogium saturninum	Small amounts (e.g., 1–4%)	Level depends on symbiotic algae and fungal components.
Higher Plants	Soybeans, peanuts, spinach	Virtually non-existent	Lack the enzymatic pathway for AA synthesis.

Benefits of Arachidonic Acid

Despite its association with inflammatory responses, AA is a crucial nutrient with several important health benefits.

Brain Health: AA is vital for brain development, especially in infants, and helps maintain cognitive function throughout life. It's one of the most abundant fatty acids in the brain.
Cellular Function: It contributes to the structure and flexibility of cell membranes, which is essential for proper cellular signaling and function.
Muscle Growth and Repair: For athletes, AA has been shown to support muscle repair and growth after physical exercise.
Immune System: AA is a precursor to eicosanoids, signaling molecules that play key roles in regulating immune and inflammatory responses.

Conclusion

For those seeking a pure plant-based source of preformed arachidonic acid, the green microalga Parietochloris incisa stands out as the richest natural option. While other lower plant forms like mosses also contain AA, higher terrestrial plants do not provide this fatty acid. For the general population, the body's conversion of linoleic acid is sufficient, but those following a strict plant-based diet or in critical life stages like infancy may benefit from considering supplements derived from microbial sources. The discovery of rich plant-based sources like Parietochloris incisa highlights the complex and diverse world of plant biochemistry and offers new possibilities for nutritional science.

Authoritative Reference

For more information on the role of arachidonic acid in human health, see this article by the U.S. National Institutes of Health: Arachidonic acid as a potentially critical nutrient for vegetarians and vegans? A systematic review of observational studies.

Frequently Asked Questions

Despite its name being derived from the Latin word for peanut (arachis), arachidonic acid is not found in high amounts in peanuts. The name is a point of common confusion, but peanuts primarily contain the saturated fatty acid arachidic acid.

Arachidonic acid is a precursor to eicosanoids, some of which can be pro-inflammatory, while others are anti-inflammatory. The balance of these signaling molecules is crucial for a healthy immune response. Chronic inflammation is more related to an imbalance in fatty acid intake, rather than AA itself.

Most healthy adults on a vegan diet can produce sufficient AA from the linoleic acid found in nuts, seeds, and oils. However, during critical life stages like infancy and pregnancy, preformed AA is important, and supplementation from microalgae-derived sources may be recommended.

Arachidonic acid is a specific type of omega-6 fatty acid. The body can convert the shorter-chain omega-6, linoleic acid (LA), into AA through a series of metabolic steps involving desaturation and elongation. AA is a longer-chain fatty acid and is a direct precursor to important signaling molecules.

AA is critical for the brain and eye development of infants, and its transfer via breast milk is very efficient. The synthesis of AA in infants is not sufficient to meet their high demand during this growth period, which is why it is added to infant formula.

Since higher plants are not a viable source, AA supplements are typically sourced from controlled fermentation of microorganisms. Fungi, such as Mortierella alpina, and microalgae, like Parietochloris incisa, are grown in bioreactors to produce high-purity AA, which is then extracted and used in products like infant formula or dietary supplements.

While rare, a severe essential fatty acid deficiency can lead to issues like skin problems, hair loss, and reduced immune function. For the general population, a balanced diet with enough linoleic acid and good conversion can prevent deficiency.