What is DHA?
For a long time, people shunned fats and fatty foods believing that all fats are bad for you. But experts now agree that there are some fats that are not only good for you but are actually essential. One particularly important fat is docosahexaenoic acid (DHA).
To understand what DHA is, it may be helpful to have a short lesson on dietary fats. There are two general types of fats: saturated and unsaturated. Saturated fats are typically found in animal products (like milk and butter) and are hard at room temperature. Since saturated fats have been linked to a higher risk for heart disease, people are advised to limit their consumption of these fats.
DHA is an unsaturated fat. Unsaturated fats, which are liquid at room temperature, are found in vegetable oils, some animal products, nuts, seeds and soy and have a number of health benefits. It’s important to get these fats in your diet.
Two types of unsaturated fats are omega-3 and omega-6 fatty acids. DHA is an omega-3 fatty acid, a type of fat that generally comes from fatty fish and marine plants like algae. The body can make some DHA from another omega-3 fatty acid, eicosapentaenoic acid (EPA), but the process is inefficient, making it important to get DHA from the diet or from supplements. EPA is found in the same foods as DHA and together they are known as fish oils.
In addition to its eye health benefits, DHA, along with EPA, supports heart and brain health and is important for pregnant and lactating women.
DHA in the Diet
The best source of DHA is fish, particularly fatty varieties like salmon, mackerel, tuna, halibut, anchovies and sardines. It is also found in some fortified foods, like eggs and milk.
The European Food Safety Authority (EFSA) recommends 250 mg of EPA and DHA per day for adults as well as children aged two to 18 years. EFSA also recommends that infants over six months of age and small children under age two have a minimum intake of 100 mg of DHA per day.
DHA in the Eye
EPA and DHA are found in the walls surrounding our cells (known as cell membranes) and help keep those cell walls fluid and flexible. Because the eye membranes are among the most fluid and flexible membranes we have in our bodies, they contain a large amount of EPA and DHA. DHA is also thought to allow help the retina convert light into electrical signals. DHA contributes to the maintenance of normal vision.
DHA’s role in eye health starts very early. During pregnancy, DHA – and to a certain extent EPA – accumulate in the brain and the eye of the fetus, especially during the last trimester of pregnancy, leading scientists to believe that DHA is important for brain development and visual acuity. The role was thought to be so important, in fact, that in the 1990s, DHA was added to infant formulas in Europe to better replicate what was in breast milk. More recently, the European Food Safety Agency recognized that maternal intake of an additional 200 mg./day above the recommended intake for adults contributes to the normal development of the eye of the fetus and breastfed infants.