Sialic acid (N-acetyl and N-glycolylneuraminic acid) and ganglioside in whey protein concentrates and infant formulae

Sialic acid and gangliosides content and profiles were analyzed in infant formulae, whey protein concentrates and human milk. In infant formulae, N-acetylneuraminic (Neu5Ac) and N-glycolylneuraminic (Neu5Gc) acid ranged from 147.6–199.7 to 3.3–8.3 mg L−1, in whey protein concentrate from 1.6–2.4 g 100 g−1 to 2.8–20.2 mg 100 g−1 and in human milk from 299.9 to 2.1 mg L−1. Gangliosides ranged from 0.25 to 2.29 mg lipid-bound sialic acid L−1 in reconstituted infant formula, the main gangliosides being GD3 (73.3–55.5%), GM3 (3.5–36.6%) and GT3 (1.4–14.1%) and O-acetyl-GD3 (5.3–18.9%). In whey protein concentrates, 0.7–55.6 mg lipid-bound sialic acid 100 g−1 were found with the profile 82.1–86.9% GD3 and 1.8–2.5% GM3. Human milk gave 2 mg lipid-bound sialic acid L−1, with the profile 97.4% GM3 and 2.5% GD3. Intakes of sialic acid and gangliosides are lower with infant formulae versus human milk, especially during the first stages of life.