What Are Essential Fatty Acids?
Essential fatty acids (EFAs) are a class of polyunsaturated fats that are necessary for normal physiological function but cannot be synthesized by the body. This means they must be acquired through diet. The two fatty acids that are truly essential for humans are linoleic acid (LA) and alpha-linolenic acid (ALA). These two fatty acids are precursors for other longer-chain fatty acids that also play vital roles in the body, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
The Foundational Essential Fatty Acids
Linoleic Acid (LA): The Foundational Omega-6
Linoleic acid is the primary omega-6 fatty acid and is widely available in the modern food supply. It is a fundamental component of cell membranes, helping to maintain their integrity and fluidity. Your body uses LA to produce other omega-6 derivatives, including arachidonic acid (AA), which is a precursor for eicosanoids that regulate inflammation and immune responses. Sources of LA include common vegetable oils like soybean, corn, and safflower oil, as well as nuts and seeds. While crucial, the Western diet often has an imbalanced omega-6 to omega-3 ratio, with excessive omega-6 intake potentially contributing to inflammation.
Alpha-Linolenic Acid (ALA): The Plant-Based Omega-3
Alpha-linolenic acid is the primary plant-based omega-3 fatty acid. It is the precursor for the longer-chain omega-3s, EPA and DHA, although the body's conversion of ALA to these forms is quite inefficient. ALA is especially beneficial for cardiovascular health, with studies showing it can help lower cholesterol and blood pressure. Key sources of ALA include:
- Flaxseed and flaxseed oil
- Chia seeds
- Walnuts
- Canola oil
- Soybean oil
The Importance of the Omega Balance
Maintaining a balanced intake of omega-3 and omega-6 fatty acids is more important than simply consuming enough of each. In ancestral human diets, the ratio of omega-6 to omega-3 was much lower, possibly around 1:1. Today's Western diets can have a ratio as high as 15:1 or more, which promotes inflammation and can contribute to chronic diseases. Balancing this ratio can help modulate inflammatory responses and support overall health. While omega-6 fatty acids are essential, aiming for more omega-3-rich foods can help redress this imbalance.
Omega-9 Fatty Acids: Not Essential, but Beneficial
Omega-9 fatty acids, such as oleic acid, are not considered essential because the human body can produce them. Nevertheless, they offer important health benefits. Oleic acid, the most common omega-9, helps lower levels of LDL ('bad') cholesterol while maintaining levels of HDL ('good') cholesterol, which reduces the risk of cardiovascular disease. A diet rich in omega-9s, like the Mediterranean diet that heavily features olive oil, is widely associated with good health outcomes.
Sources of Beneficial Omega-9s:
- Olive oil
- Avocados and avocado oil
- Almonds and hazelnuts
- Peanut oil
Comparing Essential and Non-Essential Fatty Acids
| Feature | Omega-3 (ALA) | Omega-6 (LA) | Omega-9 (Oleic Acid) |
|---|---|---|---|
| Essential? | Yes | Yes | No (body can make it) |
| Primary Source | Flaxseed, walnuts, chia seeds | Vegetable oils (soybean, corn), nuts, seeds | Olive oil, avocados, nuts |
| Converted to | EPA and DHA (inefficiently) | Arachidonic Acid (AA) | None (endogenously made) |
| Key Health Role | Anti-inflammatory, brain health, heart health | Cell structure, skin health, inflammation (can be pro-inflammatory in excess) | Lowers LDL cholesterol, heart health benefits |
Essential Fatty Acid Deficiency and Dietary Recommendations
Since LA and ALA are essential, a deficiency can occur if dietary intake is insufficient. This is most often seen in patients with malabsorption issues or those on long-term fat-free feeding. Symptoms can include rough, scaly skin, dermatitis, and poor growth. For optimal health, official guidelines suggest a minimum daily intake of ALA and LA, with specific amounts varying by age and sex.
For adults, general recommendations include:
- ALA: Men need about 1.6 g per day, and women need 1.1 g per day.
- LA: For adults aged 19–50, the Adequate Intake is around 17 g/day for men and 12 g/day for women.
However, focusing solely on these minimums may not be enough. Given the poor conversion of ALA to EPA and DHA, and the potential pro-inflammatory effects of excess omega-6, it is wise to prioritize a balance of omega fats in your diet. This can be achieved by incorporating regular servings of fatty fish or, for vegetarians, algal oil, alongside plant-based ALA sources. The American Heart Association recommends two servings of fish per week for cardiovascular health.
Conclusion
The answer to the question "Which of the following are considered essential fatty acids in Quizlet?" is straightforward: linoleic acid and alpha-linolenic acid. These are the two fats that our bodies cannot produce, making their presence in our diet mandatory. Beyond this basic answer lies a more nuanced understanding of fatty acids. A healthy diet involves not only meeting the minimum requirements for LA and ALA but also paying attention to the overall balance of omega-3, omega-6, and other healthy fats like omega-9. By consciously choosing diverse food sources, you can ensure your body receives all the necessary building blocks for optimal cellular function, inflammation control, and long-term health.
For more detailed nutritional information and daily recommendations, consult a resource like the National Institutes of Health.
