Docosahexaenoic acid (DHA) is a long-chain polyunsaturated omega-3 (n-3) fatty acid considered to be nutritionally essential to maintain optimal health. There are a number of known health benefits associated with omega-3 fatty acid intake, with most current research focusing on the n-3 fatty acids DHA and EPA (eicosapentaenoic acid). In the body, DHA is an important component of cell membranes, particularly in the brain and retina. However, the human body cannot synthesize omega-3 fatty acids on its own, so these nutrients must be provided by the diet. By consuming the n-3 fatty acid alpha-linolenic acid (ALA) from sources such as flax seed, the body can convert ALA into EPA and eventually DHA, but the low rate of conversion supports direct dietary intake of DHA from foods and dietary supplements 1. The major food sources of DHA, as well as EPA, are algae and cold-water oily fish, such as salmon, herring, mackerel, anchovies and sardines 2. Dietary supplements containing significant amounts of EPA and DHA are typically fish oils derived from these fish. In addition, infant formulas often contain supplemental DHA. The U.S. Food and Drug Administration (FDA) has determined that the use of DHA and EPA omega-3 fatty acids as dietary supplements is safe, provided that the daily intakes of DHA and EPA do not exceed 2 grams per day from dietary supplement sources such as fish oil 3. A major safety concern is the possible presence of heavy metals and toxins, which can be found in relatively high levels in fresh fish and unpurified fish oils. When considering omega-3 DHA and EPA dietary supplements, it is important to look for fish oils that have been purified to reduce the levels of these contaminants.