Analyses of DHA in breastmilk from Norwegian women (unpublished data, Institute of Marine Research) indicate that the great majority of breastfed infants in Norway receive considerably higher amounts of this fatty acid than what the European Food Safety Authority reports to be sufficient (Table 1). Supplements of cod liver oil will provide infants who are breastfed as well as infants who receive infant formula with a DHA intake which is several times as high as recommended (4–7 times higher, or more if the breastfeeding mother's intake is high). Five millilitres of cod liver oil alone will provide 600 mg of DHA, as well as 400 mg of the omega-3 fatty acid eicosapentaenoic acid (EPA).
Recommendations for nutritional supplements must be adapted to each family in question
Possible negative effects of a high intake of these fatty acids in infants include a reduced conversion of linoleic acid to arachidonic acid and a reduced immune response (13, 14). However, little research has been undertaken on high intake of DHA and EPA in infants (15). On the other hand, there is no evidence that an intake of these fatty acids in excess of the recommendations provides any health benefits (15, 16). An expert group appointed by the European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) has stated that unnecessary amounts of nutrients and other components should be avoided in infants, because they may put a burden on the metabolic and other physiological functions of the infant (17).
Despite purification, cod liver oil contains small amounts of environmental toxins, such as dioxin and dioxin-like polychlorinated biphenyls (PCB) (18). The Norwegian Scientific Committee for Food and Environment has launched efforts to map the intake of these environmental toxins from foods, including cod liver oil, and their possible effects (19).
A breastfeeding woman who follows the nutritional recommendations from the Norwegian Directorate of Health will have a sufficient content of DHA in her breastmilk. If she eats a fully or mainly plant-based diet, she should take supplements that contain vitamin D, vitamin B12 and iodine, as well as DHA in the form of plant-derived omega-3 (from algae oil). In such cases, the breastfed infant may be given a supplement that contains vitamin D and vitamin B12 (20).
Recommendations for nutritional supplements must be adapted to each family in question. The time when everybody could receive the same advice is over.