Docosahexaenoic acid, commonly known as DHA, is an omega-3 fatty acid. It is a polyunsaturated fatty acid that serves as an important component of various bodily structures. DHA is particularly important for the brain, cerebral cortex, skin, and retina, playing a role in their development and function. This fatty acid contributes to the optimal functioning of neuronal membrane proteins and is highly concentrated in brain and retinal cells, supporting cellular functions throughout the body and overall health.
DHA in Foods
Primary dietary sources of DHA for humans are fatty fish. Cold-water fatty fish such as salmon, mackerel, sardines, tuna, and herring are rich in this omega-3 fatty acid. For instance, a 3.5-ounce serving of cooked salmon can contain approximately 1,000 milligrams of omega-3s, including DHA. Mackerel can offer even higher amounts, with a 3.5-ounce serving providing around 4,580 milligrams of omega-3 fatty acids. Sardines also provide a substantial amount, with about 1.5 grams of omega-3 fatty acids per 3.5-ounce serving.
These fish accumulate DHA by consuming smaller marine organisms abundant in these fats. DHA can also be found in other seafood like oysters and anchovies, though often in smaller concentrations. Beyond seafood, some foods are fortified with DHA to enhance their nutritional value, such as certain brands of eggs, milk, yogurt, and infant formulas.
The Ultimate Marine Origin
The primary source of DHA in the ecosystem traces back to microscopic organisms in marine environments. Microalgae and phytoplankton are the primary producers of DHA in the ocean. These tiny organisms synthesize DHA from simpler fatty acids, forming the base of the marine food web and initiating its transfer throughout the aquatic ecosystem.
Smaller fish consume these microalgae and phytoplankton, accumulating DHA. As larger fish prey on these smaller fish, DHA becomes further concentrated up the food chain. This process explains why fatty fish, positioned higher in the marine food web, are rich sources of DHA for human consumption. The DHA found in fish ultimately originates from these microscopic marine plants.
Other Avenues for Obtaining DHA
Beyond consuming fish, individuals can obtain DHA through various supplements. Fish oil supplements, derived from fatty fish, are a common option and contain both DHA and EPA (eicosapentaenoic acid). Algae-based DHA supplements offer a vegetarian and vegan-friendly alternative, as they source DHA directly from the microalgae that produce it. These supplements provide a direct way to increase DHA intake, especially for those who do not consume fish.
The human body can also produce some DHA from alpha-linolenic acid (ALA), another omega-3 fatty acid found in plant sources like flaxseed, chia seeds, and walnuts. However, the conversion of ALA to DHA in humans is inefficient and limited. Conversion rates are less than 4%, and can be as low as 0.3% to 1%. This inefficiency indicates the need to obtain DHA directly from dietary sources or supplements for adequate levels.