Technically, all DHA is plant-based. DHA derived from fish sources originates in plants and is progressively concentrated as it moves through the food chain. An advantage of fish-based DHA lies in the fact that the food chain is more economical and efficient at concentrating DHA than the processes used on plant-based DHA. This equates to typically less expense and smaller size for prenatals with fish-based DHA.

Some advocates of plant-based DHA assert that this form is free of “fishy” odor and taste. This is absolutely wrong. It is DHA and other fatty acids that have oxidized (gone rancid) which give fish that odor and taste, not the fish which imparts these to the DHA. Plant-based DHA that is oxidized (rancid) will smell and taste “fishy.”

Another argument for plant-based vs fish-based DHA is that there are no concerns over contaminants with the plant-based version. While this is true, the multi-stage cleansing and processing of the fish oil used in the best prenatal vitamins eliminates mercury, pesticides, and other contaminants so completely that they are of absolutely no concern.

An important advantage that fish-based DHA has over plant-based DHA is that the fish source also includes EPA, another very important essential fatty acid for both mother and baby. When EPA levels are low, as is often the case for pregnant women, some DHA will be broken down and reassembled into EPA to meet the needs for EPA. This reduces the amount of DHA that is available.