Which of the following is true about essential fatty acids? A definitive breakdown

December 22, 2025 •

3 min read

Essential fatty acids (EFAs) are required for optimal health but cannot be synthesized by the body and must be obtained from dietary sources. This is the most fundamental fact to remember when asking yourself which of the following is true about essential fatty acids, highlighting their critical role as a nutrient.

Quick Summary

Essential fatty acids are vital nutrients the human body cannot produce and must get from food. They include Omega-3 and Omega-6, crucial for cell structure, brain health, and inflammation.

Key Points

Dietary Necessity: Essential fatty acids must be obtained from food sources because the human body cannot produce them.
Types and Sources: The main EFAs are Alpha-linolenic acid (omega-3, found in flaxseeds and fish) and Linoleic acid (omega-6, found in vegetable oils).
Biological Functions: EFAs are crucial for constructing cell membranes, regulating hormone production, and controlling inflammation.
Brain and Heart Health: Omega-3 fatty acids, especially EPA and DHA, play a significant role in cognitive function and cardiovascular health.
Inflammatory Balance: Maintaining a healthy balance between omega-3 and omega-6 intake is important for regulating the body's inflammatory responses.
Low Conversion Rate: The body's conversion of ALA (omega-3) into more potent EPA and DHA is inefficient, making direct intake important.

What Makes a Fatty Acid “Essential”?

The term "essential" in nutrition means a substance that is necessary for the body's proper function but cannot be created by the body itself, or at least not in sufficient quantities. Essential fatty acids (EFAs) fit this definition perfectly. Humans lack the necessary enzymes, specifically desaturase enzymes, required to introduce double bonds at certain positions along the fatty acid carbon chain. This inability forces the body to rely on external sources, namely food, to obtain these crucial fats.

The Two Main Essential Fatty Acids

There are two primary essential fatty acids, which serve as the foundation for other fatty acids in the body:

Alpha-linolenic acid (ALA): This is the parent omega-3 fatty acid. While the body can convert ALA into longer-chain omega-3s like EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), the conversion rate is often very low. Therefore, direct intake of EPA and DHA from food or supplements is often recommended for optimal health. Sources of ALA include flaxseeds, walnuts, and chia seeds.
Linoleic acid (LA): This is the parent omega-6 fatty acid. The body can convert LA into longer-chain omega-6 fatty acids, such as arachidonic acid (AA). LA is widely available in the modern diet, found in vegetable oils like corn, sunflower, and soybean oil, as well as in nuts and seeds.

Key Functions of Essential Fatty Acids

EFAs are much more than just a source of energy. They play a multitude of critical roles throughout the body, including:

Structural components: They are integral to the structure of cell membranes, ensuring their fluidity and integrity. This is particularly important for cells in the brain and retina, where DHA is highly concentrated.
Precursors for signaling molecules: EFAs serve as the starting point for producing eicosanoids, which are signaling molecules involved in regulating inflammation, blood clotting, and immune responses. The type of eicosanoids produced (pro-inflammatory or anti-inflammatory) depends on the balance of omega-3 and omega-6 fatty acids.
Cardiovascular health: Omega-3 fatty acids, in particular, are known for their cardiovascular benefits, including reducing triglycerides, lowering blood pressure, and improving heart rate.
Brain and cognitive function: DHA is vital for normal brain development and function, with studies linking it to enhanced cognition and synaptic function.

Dietary Sources of Essential Fatty Acids

Ensuring a diet rich in these key fats is crucial. Here are some examples:

Omega-3 Sources:

Fatty fish (salmon, mackerel, sardines)
Flaxseeds and flaxseed oil
Chia seeds
Walnuts
Soybeans

Omega-6 Sources:

Vegetable oils (corn, sunflower, soybean oil)
Nuts (almonds, peanuts)
Seeds (pumpkin seeds)
Poultry

Comparison: Omega-3 vs. Omega-6


Characteristic	Omega-3 (ALA)	Omega-6 (LA)
Primary Sources	Fatty fish, flaxseeds, walnuts	Vegetable oils, nuts, seeds
Conversion Pathway	Converts to EPA and DHA (low efficiency)	Converts to arachidonic acid
Associated Eicosanoids	Tend to be anti-inflammatory	Tend to be pro-inflammatory
Key Functions	Brain health, cardiovascular health, anti-inflammatory effects	Cell structure, growth, inflammation regulation
Modern Diet Status	Often insufficient	Often excessive

Balancing Omega-3 and Omega-6 Intake

While both omega-3 and omega-6 are essential, the ratio of their intake is important for health. The Western diet is typically very high in omega-6 fatty acids and low in omega-3s, leading to an imbalance that can promote a pro-inflammatory state. Increasing omega-3 intake while moderating omega-6 consumption can help restore a healthier balance. This might involve incorporating more fatty fish, flaxseeds, and walnuts into the diet and being mindful of intake from certain vegetable oils.

The Concluding Truth About Essential Fatty Acids

In conclusion, the key truth is that essential fatty acids cannot be manufactured by the human body and are a fundamental requirement of our diet. They are not optional; they are vital for cell function, brain health, and managing inflammation through signaling molecules. By understanding their sources and importance, individuals can make informed dietary choices to support overall well-being. For more detailed scientific information, the Linus Pauling Institute provides comprehensive resources on these crucial nutrients.

Frequently Asked Questions

The primary characteristic is that the human body cannot produce them on its own and therefore they must be consumed through the diet to maintain optimal health.

The two main types are the omega-3 fatty acid, Alpha-linolenic acid (ALA), and the omega-6 fatty acid, Linoleic acid (LA).

They are important because they are vital components of cell membranes, provide energy, and serve as precursors for eicosanoids, which are signaling molecules that regulate inflammation and other bodily functions.

Yes, the body can convert ALA into EPA and DHA, but the conversion rate is often very low and inefficient. For this reason, many health professionals recommend consuming sources rich in preformed EPA and DHA.

While severe deficiency is rare, insufficient intake can negatively impact overall health, potentially affecting cell function, brain health, and immune response.

Good food sources of omega-3 fatty acids include fatty fish (like salmon and mackerel), flaxseeds, chia seeds, and walnuts.

To achieve a better balance, increase your intake of omega-3-rich foods (e.g., fatty fish, flaxseeds) while being mindful of your consumption of omega-6-rich vegetable oils.