Form & Function of Omega-3s
The need for fatty acids in human nutrition was first observed in 1929 but it wasn’t until the 1960s that researchers were able to identify and actively research them. ALA is a shorter-chain omega-3 fatty acid found in seeds, nuts, and some plants. EPA and DHA are longer-chain fatty acids found in fish, seafood, and fish oil supplements. ALA provides energy (calories) and is a healthful fat in the diet but it is not a replacement for EPA and DHA. In order for ALA to function like EPA and DHA, it must be converted to EPA and DHA. This is a challenging process in humans. From scientific research we have learned that only about 5-15% of ALA converts (or changes) to EPA and less than 1% converts to DHA in most of us.
EPA and DHA have unique functions because of their different chemical structures, but they also complement each other. In fact, EPA and DHA occur together in foods and fish oils.
In general, EPA is involved in producing compounds that positively influence the immune system, inflammatory response, circulation, and heart health. More specifically, EPA is an eicosanoid. Eicosanoids are responsible for making hormone-like substances that manage and direct moment-to-moment life-sustaining tasks in cell membranes, such as reducing vascular and bronchial constriction, reducing aggregation of blood platelets and inflammatory response, and regulating production of cytokines and other immune factors. In contrast, the omega-6 fatty acid, arachidonic acid, produces eicosanoids that have opposing effects to EPA.
Due to its unique chemical structure, DHA improves fluidity, flexibility, and functionality of tissues and cells. In the brain, DHA is required for normal, healthy nerve conduction and communication within and between neurons (important brain cells); this is the functional basis for all brain activities: mechanical, emotional, sensorial, and intellectual. For example, nerve synapse, myelin production, cell signalling, and genetic transcription all use DHA. Although DHA is found throughout the body, it is of particular structural importance in the neurons in the brain, retina in the eyes, sperm in the testes, and the heart muscle.
A myriad of other functions in the body use both EPA and DHA, some of which are still being discovered. Researchers are actively studying their roles in gene expression, insulin action, and repair of cellular trauma, for example. Finally, their importance in general nutrition must not be overlooked. From infancy to old age, EPA and DHA omega-3 fatty acids are essential components of our daily nutrition.