As the child grows, the docosahexaenoic acid requirements also grow for the further development and function of the brain. Throughout the adulthood DHA is necessary for maintaining mental health. The old age related mental decline, memory loss, cognitive decline and other mental disorders are possibly the results of deficiency of the DHA in the food sources or malabsorption. However, the present American diet contains less than 100 mg of docosahexaenoic acid per day, far below the required daily allowance.
Indirect source of DHAAlpha-linolenic acid (ALA) is a polyunsaturated omega-3 fatty acid. It is an essential fatty acid. As human body cannot synthesize ALA, we have to include it in our food sources. ALA is helpful in energy production and there are no known independent benefits on brain or eye. Normally seed oils are rich in omega-3 fatty acids. Chia, flaxseed, rapeseed, pumpkin seeds and walnuts are rich food sources. Alpha-linolenic acid is a precursor for the synthesis of docosahexaenoic acid and eicosapentaenoic acid (EPA) in the body. However the process is inefficient and very small quantities of ALA get converted into DHA. Compared to women, there is further decline in the ALA to docosahexaenoic acid conversion in men.
Arachidonic acid (ARA), an omega-6 polyunsaturated fatty acid, competes with DHA and EPA for positions in cell membranes. Excess presence of ARA in fact can interfere with the docosahexaenoic acid synthesis. These omega-6 fatty acids reduce the amount of alpha-linolenic acid that's converted to EPA and DHA by up to 50%. Our present food habits contribute to intake of ARA rich sources and over-dosing in omega-6 fats. It is further affecting the conversion of ALA into DHA.
Preformed food sources of DHAConsidering the above facts, docosahexaenoic acid, being essential for many of the body functions, has to taken in the form of food or supplements. Most of the seafood such as fish, shellfish, mammals and microalgae are rich sources of preformed DHA.
Fish and fish oil
Among the fish, oily cold water fish are the rich sources of docosahexaenoic acid. Salmon contains up to 2000 mg of these fats per 6 ounce serving. Bluefin tuna, swordfish, anchovies, herring, sardines, pilchards and trout are some of the DHA rich foods. Fish oil is extracted from the fish and marketed for its high omega-3 fatty acid content.
Green lipped mussels
Green lipped mussel is a bivalve mollusk cultured extensively in New Zealand. It is consumed for its high protein and omega-3 values. Green lipped mussel oil extract and powder are marketed for their rich omega-3 fatty acid content and therapeutic values.
Hen have greater capacity for converting ALA into docosahexaenoic acid and EPA. When poultry feed is enriched with flaxseed, fish oil or DHA from algae, the eggs produced contain higher amounts of these omega-3 fatty acids.
Krill are shrimplike crustaceans found in all the world’s cold oceans. Krill body oil is rich in these omega-3 fatty acids. Due to its shell, cooking and consuming krill is difficult and unpalatable. Krill oil is extracted and marketed for its rich docosahexaenoic acid content.
Marine weeds, algae and microalgae are also rich sources of DHA. NASA associated research led to the developing a strain of microalgae yielding docosahexaenoic acid rich oil. Now algal DHA is being added to many food products to fortify them. Vegetarians and vegans can use these food sources.
Now there are changing trends and 99% of the infant formula sold in the United States is fortified with algal DHA. Docosahexaenoic acid fortified food sources like beverages, milk, yogurt and breads are now available.
Current topic on nutritional deficiency diseases:
Rich food sources of DHA.