Fish oil consumption for pregnant women

During the past two decades, a number of studies have examined whether fish oil supplements of the mothers during pregnancy might influence risk for hypertensive disorders ^{1, 2}. Randomized controlled trials have suggested potential benefits of fish oil intake in reducing risk of preeclampsia ^3-5, while other trails have found no association with respect to either gestational hypertension or preeclampsia ^{1, 2}. However, epidemiological study is in the Nordic populations have reported that high intakes of cod liver oil supplements may be associated with hypertensive disorders in pregnancy ⁶. As fish liver oil is a commonly consumed supplement in pregnancy, in the Nordic countries, it is important to investigate the association between fish liver oil intake with pregnancy complications.

Intake of cod liver oil was divided into four groups, with the lowest group reporting no intake and three groups of similar in size consuming > 0-1 g, > 1-9 g and > 9 g per day. Nutrient content of fish liver oil was calculated at the time of the study, using the Icelandic Nutrition Database (ISGEM). For cod liver oil, 1tablespoon is approximately 9 grams include 1.8 g n-3 LCPUFA, 2400 μg vitamin A (retinol), 20 μg vitamin D and 30 mg vitamin E ¹⁵.

One Icelandic study on 2011 showed that fish liver oil supplements (≈ 9 g/day) during pregnancy were associated with gestational hypertension.

In summary, this could be due to increased exposure PCBs and A-vitamin (retinol) from fish liver oil. Recommended dose of fish liver oil suggest that very high intakes (1 tablespoon ≈ 9 g/day) of fish liver oil should generally be avoided.

References

1.       Olsen SF, Secher NJ, Tabor A, Weber T, Walker JJ, Gluud C. Randomised clinical trials of fish oil supplementation in high risk pregnancies. Fish Oil Trials In Pregnancy (FOTIP) Team. BJOG. 2000 Mar;107(3):382-95.

2.       Salvig JD, Olsen SF, Secher NJ. Effects of fish oil supplementation in late pregnancy on blood pressure: a randomised controlled trial. Br J Obstet Gynaecol. 1996 Jun;103(6):529-33.

3.       Velzing-Aarts FV, van der Klis FR, van der Dijs FP, Muskiet FA. Umbilical vessels of preeclamptic women have low contents of both n-3 and n-6 long-chain polyunsaturated fatty acids. Am J Clin Nutr. 1999 Feb;69(2):293-8.

4.       Olsen SF, Secher NJ. A possible preventive effect of low-dose fish oil on early delivery and pre-eclampsia: indications from a 50-year-old controlled trial. Br J Nutr. 1990 Nov;64(3):599-609.

5.       Williams MA, Zingheim RW, King IB, Zebelman AM. Omega-3 fatty acids in maternal erythrocytes and risk of preeclampsia. Epidemiology. 1995 May;6(3):232-7.

6.       Olafsdottir AS, Skuladottir GV, Thorsdottir I, Hauksson A, Thorgeirsdottir H, Steingrimsdottir L. Relationship between high consumption of marine fatty acids in early pregnancy and hypertensive disorders in pregnancy. BJOG. 2006 Mar;113(3):301-9.