Food for thought since we are on the topic of DHA:
Copied from kellymom.com
There is no evidence whatsoever that breastmilk is deficient in DHA, and there is no evidence that DHA supplements taken by a nursing mother will improve the long term outcome or IQ of her baby. Nursing mothers who get more DHA do have have higher levels of DHA in their milk, but it is not known whether these higher levels are beneficial or what the optimal levels might be. Vegetarians, particularly vegans, tend to have lower levels of DHA in breastmilk.
Dr. Thomas Hale recommends that normal breastfeeding women should not be supplemented with polyunsaturated fatty acids (PUFAs). He indicates that while it is true that populations who ingest large quantities of fish and therefore polyunsaturated fatty acids do not have cardiovascular disease, he has indication that their rate of stroke is much higher, and so recommends that "supplements" not be used.
Nursing and pregnant women are certainly encouraged to eat natural sources of DHA and alpha linolenic acid. Good sources include:
cold water/oily fish and fish oils (e.g., salmon, mackerel, herring, tuna, sardines, anchovies); fresh fish is better, as freezing destroys some of the EFA; avoid consumption of fish that may be high in mercury
green leaves of plants, including phytoplankton and algae
some seeds and nuts (flax seeds, walnuts, canola, linseeds, pumpkin seeds)
some legumes (soy beans, Great Northern beans, kidney beans, navy beans)