DHA is more important for brain development than other omega-3 fatty acids.
As mentioned before, from the last trimester to the first two years of life, human brain accumulates a large amount of DHA. Offsprings can obtain DHA through maternal transfer across the placenta during pregnancy and human milk by breastfeeding after birth. Infants fed with breast milk, which is known to contain DHA, have higher DHA concentration in red blood cell than those fed with formula without DHA added. Therefore, the status of omega-3 in offsprings is highly variable and largely relies on their mother’s diet.
In a meta-analysis on DHA concentration in human breast milk worldwide, Brenna reported that coastal populations have the highest DHA concentrations, and the concentrations were associated with seafood consumption. A great range of DHA content was found worldwide, from 0.06% to 1.4% (Brenna et al. 2007, page 1457).
This finding is similar to Yuhas’ study which examined human breast milk fatty acid composition from nine countries including Australia, Canada, Chile, China, Japan, Mexico, Philippines, UK, and the US. They found some PUFA especially DHA are highly variable, with the highest in Japan and the lowest in Canada and US(Yuhas et al. 2006, page 851). In general, the intake of DHA during pregnancy in North America is below the recommendation(Nordgren et al. 2017; Denomme et al. 2005).
According to a survey, more than 90% of the population in the US consumed less DHA+EPA from food sources than the AHA recommendation(Richter et al. 2017, page 917). There is a growing concern that insufficient intake of DHA would put infants at a risk of deficiency in the vital early neurological development. Many studies have reported maternal or offsprings’ DHA status can be improved after maternal DHA supplementation. Montgomery et al found higher DHA concentration in plasma and erythrocytes in mothers receiving fish oil than the placebo oleic acid group during the second and third trimesters of pregnancy(Montgomery et al. 2003, page 135). Dunstan et al also observed both mothers and neonates had significantly higher omega-3 proportions in the group of women receiving high dose fish oil from 20 weeks of pregnancy until birth than the control group of receiving olive oil(Dunstan et al.
2004, page 429). Interestingly, Meldrum et al observed infant erythrocyte DHA level was strongly associated with breast milk DHA level, while the plasma DHA level was more associated with supplementation(fish oil). It is possible that plasma may reflect short-term effect and are less likely to be reflected in erythrocyte level. He concluded high dose supplementation of fish oil was not so efficient as breast milk in increasing infant DHA status(Meldrum et al. 2012, page 233).
Considering the omega-3 fatty acids benefit, working groups have recommended that during pregnancy and lactation, women must ensure 300 mg DHA intake each day, and reached a consensus on increasing omega-3 fatty acids in the diet of newborns for optimal brain and cardiovascular health(Simopoulos et al. 2000, page 120). Since 2002, FDA has approved that DHA could be added to infant formulas in the United States. Base on scientific evidence, the European Food Safety Authority has approved that DHA contributes to normal brain development in 2014.
For older infants and young children below the age of 24 months, they should consume100 mg DHA-containing foods each day in one or more servings; For 2 to 18 years old children, foods should provide 250 mg DHA each day in one or more servings.(EFSA Panel on Dietetic Products 2014, page 1).