Collectively, the essential fatty acids are polyunsaturated fatty acids. Fatty acids comprise a group of molecules with a chemical structure consisting of an even number of carbon atoms. The carbon chain of a polyunsaturated fatty acid has more than one double- or triple-combining bonds per molecule. There are five essential fatty acids.
Alpha-Linolenic Acid
Alpha-linolenic acid or ALA is an omega-3 fatty acid that cannot be synthesized by the human body. It is a type of omega-3 fatty acid that is found in plants. The highest concentration of ALA is found in flaxseed oil. Canola, soybean, perilla and walnut oils contain lesser concentrations of ALA. Other plant sources include soybeans, pumpkin seed and pumpkin seed oil, and tofu. Green vegetables, such as spinach, kale, Brussels sprouts and salad greens contain ALA. The human body can convert ALA into two other important essential fatty acids, which are eicosapentaenoic acid, EPA, and docosahexaenoic acid, DHA.
Eicosapentaenoic Acid and Docosahexaenoic Acid
These two essential fatty acids can be made by the body but the amounts vary by sex and age. Dietary sources of these omega-3 fatty acids offer higher concentrations of these essential nutrients. Fish, particularly fatty fish such as salmon, mackerel, cod, tuna and halibut are sources of EPA and DHA. Fish oil, specifically cod liver oil and sardine oil are natural dietary sources of these omega-3 fatty acids. EPA and DHA are found in shellfish, like clams, mussels, oysters, scallops and conch. Other seafood sources are octopus and crustaceans such as crab, spiny lobster and shrimp.
Linolenic Acid
Linolenic acid is an omega-6 fatty acid that the body cannot synthesize, which is why it is considered to be an essential fatty acid. Omega-6 fatty acids, along with omega-3 fatty acids promote healthy skin, bones and hair, regulate metabolism and influences brain function. Plant-based foods are the only source of linolenic acid. Nuts, seeds and their derived oils contain linolenic acid. Examples include safflower oil, sunflower seeds and sunflower oil, pine nuts, corn oil, sesame oil, pecans and Brazil nuts.
Arachidonic Acid
Arachidonic acid is a long-chain omega-6 fatty acid which all animals, including humans, can synthesize from linolenic acid. Thus, animal-based food sources, such as meat and eggs contain this essential fatty acid. According to the National Cancer Institute, sausage, frankfurters, bacon, cold cuts, ribs, burgers, pizza and eggs are sources of omega-6 fatty acids and are prevalent in the American diet.
References
- Linus Pauling Institute: Essential Fatty Acids
- University of Maryland Medical Center: Alpha-Linolenic Acid
- Harvard School of Public Health: Ask the Expert: Omega-3 Fatty Acids
- DHA-EPA Omega-3 Institute: Dietary Sources of Omega-3 Fatty Acids
- National Cancer Institute: Food Sources of Arachidonic Acid
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