Essential fats: how do they affect growth and development of infants and young children in developing countries? A literature review

Omega-3 and omega-6 fatty acids, particularly docosahexaenoic acid (DHA), are known to play an essential role in the development of the brain and retina. Intakes in pregnancy and early life affect growth and cognitive performance later in childhood. However, total fat intake, alpha-linolenic acid (ALA) and DHA intakes are often low among pregnant and lactating women, infants and young children in developing countries. As breast milk is one of the best sources of ALA and DHA, breastfed infants are less likely to be at risk of insufficient intakes than those not breastfed. Enhancing intake of ALA through plant food products (soy beans and oil, canola oil, and foods containing these products such as lipid-based nutrient supplements) has been shown to be feasible. However, because of the low conversion rates of ALA to DHA, it may be more efficient to increase DHA status through increasing fish consumption or DHA fortification, but these approaches may be more costly. In addition, breastfeeding up to 2 years and beyond is recommended to ensure an adequate essential fat intake in early life. Data from developing countries have shown that a higher omega-3 fatty acid intake or supplementation during pregnancy may result in small improvements in birth weight, length and gestational age based on two randomized controlled trials and one cross-sectional study. More rigorous randomized controlled trials are needed to confirm this effect. Limited data from developing countries suggest that ALA or DHA supplementation during lactation and in infants may be beneficial for growth and development of young children 6 to 24 months of age in these settings. These benefits are more pronounced in undernourished children. However, there is no evidence for improvements in growth following omega-3 fatty acid supplementation in children >2 years of age. (Authors abstract)
This review article describes a number of key findings from the literature. Omega-3 and omega-6 fatty acids play an important role in growth and development of infants and young children in developing and emerging countries. Intakes of omega-3 fatty acids appear to be low among many pregnant and lactating women, and non-breastfed infants. Most complementary foods are low in omega-3 fatty acids, and thus young children in developing countries are at risk of low intakes. Ensuring adequate intakes of essential fatty acids and especially DHA through these life stages is crucial.  Cost effective dietary sources of these fatty acids and exclusive breastfeeding until 6 months of age, and continued breastfeeding thereafter, in addition to appropriate complementary feeding are needed to ensure adequate essential fatty acid and DHA intakes in these populations. Information is lacking on essential fatty acid intake and status in developing countries. The authors suggest that data should be collected from large-scale studies such as the Demographic and Health surveys or other nationally representative samples. In addition, more research is required to confirm the beneficial role of these essential fatty acids from diets or from supplements in growth and development of infants and young children in developing countries. Populations consuming low amounts or no animal foods will depend to a large extent or completely on the synthesis of EPA + DHA and AA by the human body. This situation applies to many people living in developing countries, who cannot afford significant quantities of animal foods. Sufficient intakes of ALA are needed, but when energy (especially fat) intakes are low, ALA would be preferentially used for energy expenditure rather than conversion to AA and EPA + DHA. Overall, the findings from this review suggest an opportunity for adequate EFA intake, and in particular ALA and DHA, intakes during pregnancy, lactation and the period of complementary feeding.  Ensuring AIs of fat and especially omega-3 fatty acids, through foods high in these nutrients is needed among mothers and children in developing countries to meet current recommendations. (Editors comments)