ARA is an essential fatty acid for the development of infants and young children
By Rob Winwood
Professor Tom Brenna is the current president of the International Society for the Study of Fatty Acids and Lipids (ISSFAL). His research group at Cornell University in Ithaca, NY, USA focuses on long chain polyunsaturated fatty acid (LC-PUFA) nutrition in the perinatal period and their role in neural and retinal development. The group shows the importance of Docosahexaenoic acid (DHA) and related LC-PUFAs as structural components of the nervous system and provides plausible mechanisms as to how they improve visual and neural function in the developing baby.
In a recent nutrition policy review paper (1), Professor Brenna questions the validity of the 2014 European Food Safety Authority (EFSA) opinion (2) that ARA need not be added to infant formula containing DHA and provides a biological rationale for the inclusion of ARA in breast milk substitutes containing DHA.
Professor Brenna has previously shown that ARA is present in human breast milk throughout the globe at similar levels (an average of 0.47% of total fatty acids) (3). ARA is critical for infant growth, brain development (4) and long-term health. ARA is a precursor to a group of important metabolites known as eicosanoids (e.g. leukotrienes, prostaglandins and thromboxanes), which have many roles in the body including regulating immune function, inflammation, fertility and blood flow (5).
Human milk contains DHA and ARA along with an abundance of the dietary precursors of these fatty acids, alpha-linolenic acid (ALA; 18:3 n-3) and linoleic acid (LA; 18:2 n-6), respectively. The amount of ARA produced from LA is small relative to the demands of growth and development (1,5), and the rate of production declines throughout early infancy (6). Hence a minimum level of ARA is required in infant formula because infant metabolism is unable to produce sufficient quantities from LA alone.
A global dietary survey of ARA and DHA intakes in adults has recently been carried out in 175 countries (7). The median ARA intake levels were between 210-250 mg/day in developed countries, but only 82 mg/day in developing countries. The FAO/WHO intake fatty acid intake recommendations (8) of 2008 state that for older infants, children and adults, an intake of 2.5% LA on the basis of total energy should be sufficient to meet the need for ARA. However, this data suggest that LA intake is not sufficient to sustain ARA levels in poorer countries. In addition, their infants will have difficulty achieving optimal ARA status once they start weaning and are no longer able to depend on meeting their requirements from breast milk. The same FAO/WHO intake recommendations (8) say there is “convincing” evidence that infants of 6 months or less require an intake of ARA of 0.2-0.3% of total energy, which may be difficult to achieve in these circumstances.
Professor Brenna (1) makes the point that ARA is the most efficacious n-6 essential fatty acid, rather than LA, which is found in high levels in western diets. He says the categorization of LA as an essential fatty acid is an “anachronistic misnomer”.
Professor Brenna concludes his recent review paper with the following statement: “The EFSA opinion implicitly considers the standard of care as breast milk substitutes free of DHA and ARA with no rationale as to why ARA should be considered optional apart from the inclusion of linoleic acid as a precursor. The standard of care for term infants is breast milk, and breast milk composition conserves ARA. When the option to safely recapitulate natural breast milk is practically feasible, as it is with modern sources of DHA and ARA, the burden of proof lies with the proposal to deviate from breast milk.”
A special thank you to Professor J. Thomas Brenna, Professor of Human Nutrition in the Division of Nutritional Sciences at Cornell University in Ithaca, New York for providing perspective on this topic.
1. Brenna TJ; “Arachidonic Acid is needed in infant formula when docosahexaenoic acid is present”; Nutrition Reviews 2016; 74:329-336.
2. EFSA Panel on Dietetic Products, Nutrition and Allergies; “Scientific opinion on the essential composition of infant and follow-on formula”; EFSA J 2014; 12:3760.
3. Brenna TJ, Varamini B, Jensen RG, et al.; “Docosahexaenoic and arachidonic acid concentrations in human breast milk worldwide”; Am J Clin Nutr 2007; 85(6):1457-64.
4. Martinez M; “Tissue levels of polyunsaturated fatty acids during early human development”; J Pediatr 1992: 120 (4 Pt2): S129-138.
5. Pawlosky RJ, Lin YH, Llanos A, et al.: “Compartmental analyses of plasma 13C- and 2H-labeled n-6 fatty acids arising from oral administrations of 13C-U-18:2n-6 and 2H5-20:3n-6 in newborn infants”. Pediatr Res 200; 60(3): 327–333.
6. Carnielli VP, Simonato M, Verlato G, et al.; “Synthesis of long-chain polyunsaturated fatty acids in preterm newborns fed formula with long-chain polyunsaturated fatty acids”;Am J Clin Nutr 2007; 86 (5):1323-30.
7. Forsyth S, Gautier S, & Salem Jr N; "Global Estimates of Dietary Intake of Docosahexaenoic Acid and Arachidonic Acid in Developing and Developed Countries"; Annals of Nutrition and Metabolism 2016, 258-267. http://doi.org/10.1159/000446855
8. Joint FAO/WHO Expert Consultation of Fats and Fatty Acids in Human Nutrition, 10-14 November 2008, WHO, Geneva. “Summary of Conclusions and Dietary Recommendations on Total Fats and Fatty Acids”; 2010.