fish oil supplementation

A recent study investigates if maternal fish oil supplementation during lactation affected growth and blood pressure in adolescents and if the results differed according to gender. Despite other contradicting literature, this study shows that fish oil intake reduces height by delaying pubertal maturation.


It is a known fact that breastfeeding and breast milk is healthy for both the mother and infant. It is an important source of docosahexaenoic acid (DHA) and n-3 long-chain polyunsaturated fatty acids (LCPUFA) especially when compared with formula feeding. DHA, which is a type of omega-3 fatty acid, improves the functioning of the brain, cerebral cortex, retina, and skin. However, polyunsaturated fatty acids (PUFAs), more specifically, n-3 LCPUFA are types of fatty acids that have conflicting results in scientific literature on whether or not they are beneficial. Where other studies state the n-3 LCPUFA is a beneficial supplementation for infants and is important to their neurodevelopmental outcome, the findings from a new study show that there are negative effects that can be seen later in life, at the age of 13.

A recent study published in the British Journal of Nutrition examined how dietary consumption of n-3 LCPUFA as an infant can have long-term effects and cause various health issues. More specifically, this double-blinded randomized control trial examined whether maternal fish oil (FO) supplementation during lactation affected growth and blood pressure in adolescents and if there was a difference between each gender. The experimental group consisted of 47 mother-infant pairs and 100 children that were assessed based on their growth, blood pressure, diet by Food Frequency Questionnaire and physical activity. Mother and infants consumed FO or olive oil (OO) supplements during the first four months of lactation and then follow-up studies were conducted when children were 9 months old, 2.5 and then 7 years.

Lauritzen et al. recruited Danish pregnant women from the Danish National Birth Cohort (DNBC) during December 1998 to November 1999. They were selected based on the region they lived in and their self-reported n-3 LCPUFA intake from fish. The women were then randomly allocated to two groups, FO and OO, which occurred 9 days after delivery and the mothers received supplements during the first 4 months of lactation. Data was collected based upon infant growth, which was assessed twice during the supplementation period, at 2 and 4 months old. Other measurements included length, height, head circumference and background information such as parental education, health, and anthropometry. After 13 years, for the mothers that had not withdrawn from the study, the investigators did a follow-up examination, collected blood samples from 49% of the children and analyzed it.

Based on the analysis, it was found that the children from the FO group were approximately 3.4 cm shorter than those from the OO group and had less advanced puberty, which was used as an explanation for their lack of height. There was also a difference between gender, related to diastolic blood pressure. There was a higher diastolic blood pressure by 3.9 mmHg in the FO group when compared to the OO group among boys but no difference was seen between the groups of girls. Between the two randomized groups, it was found that there were no differences observed in the content of the major fatty acids in the whole blood at 13 years old. However, the children from the FO group were shorter than the OO group and at 13 years old and the FO group had a lower puberty score. Therefore, it can be concluded that blood pressure was independent of the effect on height.

In order to enhance these results, future studies should strive to have a sample size where all the blood samples can be collected, as having long-term studies already acts as a limitation. Moreover, to respect the children’s sexual privacy, puberty-related questions were self-assessed, which can also have an influence on the results due to the child’s age, their lifestyle, and diet. Knowing how n-3 LCPUFA can possibly relate to biological effects, such as high blood pressure in boys that can lead to cardiovascular disease or a stroke, can lead to an important method of prevention that can be done early on during pregnancy. On a global level, this research can also be applied as it is in Nordic countries, especially Norway, where fish intake and FO supplementation are high and these countries have populations that are among the tallest in the world.


Written By: Seema N. Goolie, BSc

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