Lipids in the First 1000 days
Dietary lipids are important in infancy to ensure infants meet their high energy needs.1 They also fulfil numerous metabolic and physiological functions critical to their growth, development, and health. Fats contribute approximately 40% – 55% of total energy in breast milk. Breast milk contains various fats including triglycerides and long-chain polyunsaturated fatty acids (LC-PUFA) of the n-6 and n-3 series.1 The lipid content of breast milk is approximately 3.5 to 4.5g/100g and varies considerably with the length of time the mother has been breastfeeding, the time of day, and even the increases during individual feeds.1 Milk fat globules found in breast milk mainly contain a core of “triglycerides and small amounts of monoglycerides, diglycerides, and nonesterified fatty acids, surrounded by a milk fat membrane with different phospholipids, esterified cholesterol, glycosylated polypeptides, filaments, mucin, lactadherin, and other components”.1
The fatty acid composition of breast milk is markedly influenced by maternal dietary intake.1 For example, the proportions of the essential PUFA linoleic acid (LA) and alpha-linolenic acid (ALA) in breast milk depend on the mother’s diet and thus vary widely (10% – 24% of fatty acids and 0.6% – 1.9% of fatty acids, respectively.1 The major differences between breast milk and infant formulae lie in the variety of saturated fatty acids (such as palmitic acid, including its structural position) and unsaturated fatty acids (including arachidonic acid and docosahexaenoic acid), cholesterol, and complex lipids.1 Maternal dietary intake of oily fish is extremely variable which leads to the wide range of docosahexaenoic acid (DHA) values found in breast milk.1 Furthermore, many Western countries have an arachidonic acid (ARA) to DHA ratio of 2:1 and this is often mimicked in infant formulae.1 However, Scandinavian and Asian countries eat more fish than Western cultures and the ratios of ARA: DHA are far lower in these countries.1
The nervous system is especially rich in DHA. DHA accumulation in nervous tissues is especially imperative in the first 1 000 days of life when the growth and differentiation of the central nervous system are most rapid.1 DHA is also an important structural component of retina lipids, comprising as much as 50% of total fatty acids of rod and cone outer segments.2 Brain accumulation of ARA also occurs during pre- and post-natal development.2 It has been noted that breastfed infants have a greater proportion of DHA in their erythrocytes and brain cortex relative to those fed infant formula with no added DHA. However, in infants who have been fed an infant formula rich in DHA, it has been shown to have similar benefits in visual, neural or growth outcomes as compared to breastfed infants.1 It is thus recommended that pregnant and lactating mothers in Westernised countries utilise DHA supplementation should they not be eating sufficient amounts of oily fish in their diets. In addition, those infants being fed an infant formula should rather be fed an infant formula rich in the essential PUFAs, LA and ALA and LCPUFAs in a range that is similar to that found in breast milk.2
In conclusion, lipids in breast milk are extremely multifaceted and varied, and their physiological roles are not yet fully understood. Current evidence shows the importance of a quality lipid profile in breast milk and its impact of future health outcomes. Subsequently, interventions to improve the quality of the lipid intake of breastfed infants by modifying the dietary supply of women during pregnancy and lactation should be focused on in populations in order to improve the lipid supply in utero and during breastfeeding.
References
- Delplanque, B., Gibson, R., Koletzko, B., Lapillone, A., Strandvik, B. Lipid quality in infant nutrition: Current knowledge and future opportunities. (2015). JPGN, 61(1): 8-17.
- Ko;etzko, B. et al. The roles of long-chain polyunsaturated fatty acids in pregnancy, lactation and infancy: review of current knowledge and consensus recommendations. (2008). J Perinat Med, 36(1):5-14. doi: 10.1515/JPM.2008.001.
