Teneurs en acides gras polyinsaturés essentiels du lait maternel en France : évolution des teneurs en acides linoléique et alpha-linolénique

Abstract

Background: Long-chain polyunsaturated fatty acids (LC-PUFA) are nutritionally important constituents of breast milk to support normal growth, immune function and central nervous system development of newborn infants. Both linoleic acid (18:2 n-6; LA) and alpha-linolenic acid (18:3 n-3; ALA), the essential fatty acids, precursors of n-6 and n-3 LC-PUFA, are also present in breast milk. Although the total amount of fat in human milk is fairly constant, the fatty acid composition can vary substantially depending on the diet of the mother. Large variations in the LA, ALA and DHA (22:6 n-3) contents are observed among countries. As reported by previous studies, the ALA consumption of the French population was 2-3 times lower than the recommended value. Since this period, the food industry offers more food products enriched in n-3 fatty acids. Objective: The present study aimed to investigate whether nutritional recommendations and the improvement of the n-3 PUFA content of foodstuffs have contributed to an improvement of the PUFA composition of human milk. For this purpose, the PUFA content of a large number of human milk samples collected in 2007 in different French regions were compared with previous data obtained in studies conducted in the nineties years (1993-1998).Study design and methods: Mature (postpartum day ≥ 30) human milk samples (n = 145) were provided in 2007 by eight French regional human milk banks (Bordeaux: n = 20; Dijon: n = 21; Ile-de-France: n = 18; Lyon: n = 20 ; Montpellier: n = 18 ; Nantes: n = 21 ; St Etienne: n = 6 ; Tours: n = 21), from healthy women volunteers with no particular health history. The fatty acid composition of breast milk was analyzed by high-resolution gas-liquid chromatography. Statistical analysis was performed with Kruskall Wallis and Mann and Whitney U tests (p Fatty acid composition of human milk samples did not differ significantly among the eight French regions. The proportions of saturated fatty acids were similar (means ranging from 44.9% to 48.7% of total fatty acids). Monounsaturated fatty acids also varied little, from 36.9% to 39.7%. Total n-6 and n-3 PUFA accounted for 12.5%-15.2%, with the n-6/n-3 PUFA ratio value close to 10, similar among the collect centers. Considering the overall results, LA ranged from 10.4% to 12.7%, and ALA from 0.72% to 0.95%. Comparison of previous data (1993-1998) to the present results showed opposite changes in both LA and ALA contents. Between the two periods, the LA level decreased by 17%, whereas the ALA level increased by 45%, and consequently the LA/ALA ratio value favorably decreased from 24 to 15. The LC-PUFA content remained unchanged.Conclusion: Basing on the PUFA composition of human milk, this large French study has showed favourable changes in consumption of both omega-6 and omega-3 fatty acid precursors.