Only two fatty acids are considered essential because the human body cannot make them on its own. They are the omega-3 polyunsaturated fatty acid called alpha-linolenic acid and the omega-6 polyunsaturated fatty acid known as linoleic acid. These fatty acids must be obtained from the diet and are used not only for energy production, but also as building blocks for many important biological molecules. These fatty acids are the main structural units of cell membranes, they are used to synthesize molecules that regulate immune system function, inflammatory processes and nervous system function. Plus, they are involved in modulating gene expression.
Alpha-Linolenic Acid
Alpha-linolenic acid is an omega-3 fatty acid and is found in high concentrations in oily fish such as salmon, halibut and herring, and in flaxseed, walnuts, canola oil and spinach. The Office of Dietary Supplements, or ODS, states people should consume more omega-3 fatty acids to promote good health. The ODS reports that diets high in omega-3 fatty acids are linked to a significant decrease in the risk of cardiovascular disease. Additionally, the ODS reports that omega-3 fatty acids may reduce symptoms or rheumatoid arthritis and decrease the risk of developing Alzheimer's disease.
Linoleic Acid
Linoleic acid is an omega-6 fatty acid and is found in high concentrations in meats and corn, safflower, sunflower and soybean oils. The ODS notes that the majority of Americans consume 10 times more omega-6 fatty acids than omega-3 fatty acids. The University of Maryland Medical Center reports that omega-6 fatty acids are important for brain function and growth and development. This source also reports that linoleic acid is converted in the body to gamma-linolenic acid, which as a supplement has reduced nerve pain in patients with diabetic neuropathy and joint pain in people with rheumatoid arthritis.
Conditional Fatty Acids
The long-chain omega-3 fatty acids called eicosapentaenoic acid and docosahexaenoic acid are made in the liver from alpha-linolenic acid and arachidonic acid is synthesized from linoleic acid. Under some conditions, such as end-stage liver disease the synthesis of these fatty acids is compromised making them conditionally essential. In infants, arachidonic acid and docosahexaenoic acid are required at higher levels for brain and eye development. A review of clinical studies in the journal Critical Reviews in Food Science and Nutrition reports that infants who are not breastfed may benefit from formulas that are fortified with arachidonic acid and docosahexaenoic acid.
References
- Linus Pauling Institute: Essential Fatty Acids
- Office of Dietary Supplements: Omega-3 Fatty Acids and Health
- University of Maryland Medical Center: Omega-6 Fatty Acids
- "Critical Reviews in Food Science and Nutrition"; Dietary PUFA for Preterm and Term infants: Review of Clinical Studies; M. Fleith and M. Clandinin; 2005
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