Relevant regulations of the European Commission stipulate that all infant and follow-up formulas must contain DHA, while ARA is an optional ingredient.
Globally, with a few exceptions, breast milk samples consistently showed greater concentrations of ARA than DHA and double the amount of ARA. In addition, the denaturation of ARA concentration was lower than that of DHA.
The first 1000 days of life are a critical window of development, and the nutrition provided during this time plays a fundamental role in building lifelong health. 3 Breast milk remains the gold standard for promoting optimal growth and development of infants and protecting infants from infections and nutritional deficiencies. 4 Lipids are an important source of energy for breast milk and play a unique role in the health and development of infants.
Breast milk always provides the long-chain polyunsaturated fatty acids (LCPUFAs) ARA and DHA, suggesting an important role for these lipids in infant nutrition. DHA and ARA are abundant in tissues of the brain, eyes, heart, muscles, blood vessels, and immune cells. The role of these LCPUFAs in growth and brain, vision, and immune development and function has been studied over the past few decades
The ability of infants to synthesize ARA from the precursor fatty acid linoleic acid (LA) is influenced by sex, genetics, and the amount of LA in the diet. Conversion of LA to ARA is not sufficient to maintain stable ARA concentrations in plasma and erythrocytes. Therefore, supplemental sources of ARA and follow-up formula may need to be added to infants to more closely approximate the reported ARA concentrations in breastfed infants. ((5,13)) This is particularly relevant for infants carrying a genetic variant that negatively affects the ability to convert LA to ARA. This affects 30% of the general population in Europe, with lower ARA status compared to infants without the genetic variant. Reduced ARA status may affect cognitive and immune system development, as well as the risk of developing allergies.
Most studies on LCPUFAs show that certain developmental and physiological outcomes are sensitive to the ratio of ARA to DHA. For example, functional outcomes in term infants were affected by the ARA: DHA ratio in a large randomized controlled trial that provided a fixed concentration of ARA (0.64% ARA to total fatty acids) versus varying concentrations of ARA during the first 12 months of life. DHA concentrations (0.32, 0.64, or 0.96% DHA of total fatty acids) were combined. 15 In a long-term follow-up study of this cohort, positive effects on certain neurodevelopmental markers were observed at three to six years of age when ARA concentrations were at least equal to or greater than DHA (1:1 to 2:1 ARA: DHA ratio) influences.
An effective immune response includes the activation and resolution of inflammation. ARA supports the health of infants through its effects on the immune system and inflammatory response. ARA is the main substrate for the synthesis of eicosanoids, which function to regulate inflammation. Additionally, studies have shown that the balance between ARA and DHA is important. Feeding infant formula in the proportion found in breast milk, supplemented with DHA and ARA in proportion, had a positive effect on immune system markers. 13-14 Conversely, providing high doses of omega-3 LCPUFA (such as DHA) without the addition of ARA results in an imbalance in the omega 6:omega 3 LCPUFA ratio in the diet, which reduces the cellular content of ARA. Scientists believe this may lead to anti-inflammatory and immunosuppressive effects, which are undesirable in the early postpartum period when the immune system is rapidly developing and acquiring essential functions.
Based on a review of research evidence published over the past several decades, pediatric nutrition experts agree that infants need to be provided with a balanced supply of DHA and ARA to support their LCPUFA status, as well as brain and immune system development and function.