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One in 10 pregnant women has omega-3 deficiency

January 20, 2014
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Ten per cent of pregnant Canadian women have a type of omega-3 fatty acid deficiency and their babies are more likely to be behind in language development at 18 months of age, new research has found

DHA, or docosahexaenoic acid, is an omega-3 fatty acid that tends to be underrepresented in the Canadian diet. It is found in seafood such as salmon and some types of free-range chickens and eggs.

The study is the first to show a DHA deficiency among Canadian women and that increasing their DHA intake reduces risks to their child’s development. The findings were published in the scientific journal PLOS One on January 10, 2014.

"Ten per cent of the population is a lot of children who are not reaching their potential," says Dr. Sheila Innis, the study’s principal investigator. Dr. Innis is a scientist and director of the Nutrition & Metabolism Research Program at the Child & Family Research Institute (CFRI) at BC Children’s Hospital, and a professor in the Department of Pediatrics at the University of British Columbia. 

According to Statistics Canada estimates, 44,113 children were born in British Columbia in 2012-2013.

"To be safe, for risk reduction, pregnant women should eat fish such as salmon that don’t contain environmental contaminants such as metal mercury, PCPs, and dioxins," she says. 

There were 270 women from the Vancouver area who participated in the study between 2004-2008. All of them ate their regular, normal diets throughout their pregnancy and kept a food log for the study. The researchers took blood samples from the mothers at 16 weeks and 36 weeks of pregnancy. Approximately half the women received a placebo while half took a daily DHA supplement of 400 mg from 16 weeks of pregnancy until the baby was born. Both groups of women had high rates of breastfeeding. 

The researchers tested the children’s vision at two months of age and their language development at 14 and 18 months. Children of DHA-deficient mothers were more likely to have slower vision and slower language development. However, the children’s visual development normalized by 12 months of age, and the DHA deficiency did not affect their gross or fine motor development. Women who were deficient and took a DHA supplement reduced the risk to their baby’s language development.

The DHA supplements only provided benefit to those women on the study who were DHA-deficient, and did not benefit women who had a healthy, adequate diet. 

"Supplements are not a replacement for a healthy, well-balanced diet," says Dr. Innis. "We used them in our study as a tool to show that the current food supply is inadequate. People who benefitted from the supplements had an inadequate diet. The food supply, diets, and the way people eat puts them at risk of deficiency. Our preference is for people to improve their diets."

Dr. Innis recommends that pregnant women obtain DHA from a well-balanced diet that includes natural sources of DHA such as salmon and other non-contaminated fish. She emphasizes the importance of eating a variety and diversity of foods with high nutrient density that are low in processed and refined ingredients.

The researchers plan further study of the mothers’ blood samples in order to identify blood biomarkers of DHA deficiency. It is part of their broader field of study to understand the nutritional needs during pregnancy, breastfeeding, and early childhood to support children in reaching their potential and in preventing disease.

This research was funded by the Canadian Institutes of Health Research. Kelly Mulder, a UBC doctoral student working with Dr. Innis, is the paper’s first author.

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