Arachidonic acid (AA) is an I polyunsaturated fatty acid found in the phospholipids of the membranes of the human body’s cells, and is abundant in the brain, muscles, and liver. This fatty acid is particularly obtained from meat products including chicken, beef, pork, and fishes. An interesting source of AA is through its accumulation in a green microalga, Myrmecia incisa, enhanced by nitrogen starvation. The general functions of AA and its metabolites including its association with coronary heart disease, oxidative stress and cancer, metabolic syndrome, insulin resistance, and its endocrine response to stress are also discussed.