CRN responds to JAMA fish oil study

In response to a study regarding fish oil use during pregnancy published in the October 20 issue of the Journal of the American Medical Association (JAMA), the Council for Responsible Nutrition (CRN), the leading trade association for the dietary supplement industry, reminds pregnant and lactating women of the undisputed importance of consuming the recommended amounts of docosahexaenoic acid (DHA) throughout pregnancy. This can be done by eating two servings of fatty fish, such as sardines or anchovies, per week, or taking fish oil supplements (containing 200-300 mg/DHA, according to the Institute of Medicine) daily. While the benefits of DHA for a healthy pregnancy are well-established, more research is necessary to determine the effect of DHA on incidence of post-partum depression or neurocognitive development of infants.

“A large body of scientific evidence has established a strong relationship between the DHA status of mothers and infants and a variety of important pregnancy-related outcomes, including infant development,” said Duffy MacKay, N.D., vice president, scientific & regulatory affairs, CRN. “Unfortunately in this trial, we have no idea of the DHA status of the mothers at the beginning of pregnancy or when they were evaluated for depression. Further we have no idea of the DHA status of the infants at 18 months when they were evaluated for neurocognitive outcomes. Without measurements of DHA status, it is difficult to draw conclusions from the study and certainly should not provide definitive advice to consumers.”

There are many established variables that would impact individual DHA status for the mothers and children of both the supplemented and control group in this study, including differences in the ability to synthesize DHA from other fatty acids, the rate of maternal to fetal transfer of DHA, the status of other nutrients required to synthesize DHA, as well as other dietary sources of DHA not controlled for.

Dr. MacKay continued that the timeliness of the dosing may have had an impact. “Supplementation occurred from mid-term to delivery—we know that maternal DHA status returns to below pre-pregnancy levels within a few weeks from delivery. A mother in the treatment group who started the trial with low DHA status would have returned to pre-pregnancy status by the time she was evaluated for depression at six weeks and six months post delivery. We may have seen different results if these women took fish oil consistently leading up to, during and after pregnancy, or if we were able to stratify the results based on DHA status.”

This applies to the findings for the infants, as well, as there is no information about what they were given in the eighteen month period following birth—some infants in the control group may have received DHA through breast milk if the mother was eating fish or taking fish oil supplements, or through DHA-enriched formula.

“Essentially, DHA status needs to be adequate throughout pregnancy for women and their infants to receive the many established benefits,” continued Dr. MacKay. “We must also remember that both depression and childhood development are impacted by many different variables and maintaining good nutrition is just one important preventive step mothers can take to achieve the best outcomes. Taking fish oil has so many benefits; although this study did not prove that DHA dramatically impacted these complicated issues under these specific conditions, it’s still widely known to be important for pregnant women and their offspring.”