Dietary Polar Lipids and Cognitive Development: A Narrative Review

Polar lipids are amphiphilic lipids with a hydrophilic head and a hydrophobic tail. Polar lipids mainly include phospholipids and sphingolipids. They are structural components of neural tissues, with the peak rate of accretion overlapping with neurodevelopmental milestones. The critical role of polar lipids in cognitive development is thought to be mediated through the regulation of signal transduction, myelination, and synaptic plasticity. Animal products (egg, meat, and dairy) are the major dietary sources of polar lipids for children and adults, whereas human milk and infant formula provide polar lipids to infants. Due to the differences observed in both concentration and proportion of polar lipids in human milk, the estimated daily intake in infants encompasses a wide range. In addition, health authorities define neither intake recommendations nor guidelines for polar lipid intake. However, adequate intake is defined for 2 nutrients that are elements of these polar lipids, namely choline and DHA. To date, limited studies exist on the brain bioavailability of dietary polar lipids via either placental transfer or the blood-brain barrier. Nevertheless, due to their role in pre- and postnatal development of the brain, there is a growing interest for the use of gangliosides, which are sphingolipids, as a dietary supplement for pregnant/lactating mothers or infants. In line with this, supplementing gangliosides and phospholipids in wild-type animals and healthy infants does suggest some positive effects on cognitive performance. Whether there is indeed added benefit of supplementing polar lipids in pregnant/lactating mothers or infants requires more clinical research. In this article, we report findings of a review of the state-of-the-art evidence on polar lipid supplementation and cognitive development. Dietary sources, recommended intake, and brain bioavailability of polar lipids are also discussed.

The role of gangliosides in brain development and the potential benefits of perinatal supplementation

The maternal diet provides critical nutrients that can influence fetal and infant brain development and function. This review highlights the potential benefits of maternal dietary ganglioside supplementation on fetal and infant brain development. English-language systematic reviews, preclinical studies, and clinical studies were obtained through searches on PubMed. Reports were selected if they included benefits and harms of maternal ganglioside supplementation during pregnancy or ganglioside-supplemented formula after pregnancy. The potential benefits of ganglioside supplementation were explored by investigating the following: (1) their role in neural development, (2) their therapeutic use in neural injury and disease, (3) their presence in human breast milk, and (4) their use as a dietary supplement during or after pregnancy. Preclinical studies indicate that ganglioside supplementation at high doses (1% of total dietary intake) can significantly increase cognitive development and body weight when given prenatally. However, lower ganglioside supplementation doses have no beneficial cognitive effects, even when given throughout pregnancy and lactation. In human clinical trials, infants given formula supplemented with gangliosides showed increased cognitive development and an increase in ganglioside content. Ganglioside supplementation may promote brain development and function in offspring when administered at the optimum dosage. We propose that prenatal maternal dietary supplementation with gangliosides throughout pregnancy may promote greater long-term effects on brain development and function. Before this concept can be encouraged in preconception clinics, future research and clinical trials are needed to confirm the ability of dietary gangliosides to improve cognitive development, but available results already encourage this area of research.

Characterization and biological activity of gangliosides in buffalo milk

Gangliosides (GS) were evaluated in Swiss cow's milk (SCM), Italian buffalo milk (IBM) and its serum, Pakistan buffalo colostrum (PBC), Pakistan buffalo mature milk (PBM), and Pakistan buffalo milk from rice-growing areas (PBR). Dairy GS were obtained from the Folch's upper (hydrophilic) and lower (lipophilic) extraction phases, respectively, and determined as lipid-bound sialic acid (LBSA) by colorimetry. Molar ratios of LBSA in the hydro- and lipophilic GS fractions were 52:48 to 79:21. Mature buffalo milk types had 40-100% more LBSA in the lipophilic GS fraction compared to SCM. Liquid PBC was higher in LBSA (24 nmol/g) compared to mature milk types (8-11 nmol/g). Thin-layer chromatography (TLC) and scanning densitometry showed distinct profiles of hydrophilic and lipophilic GS fractions. Lipophilic GS (but importantly not hydrophilic GS) from IBM and its serum decreased prostaglandin series 2 production by 75-80% in cultured human colonic epithelial cells exposed to tumor necrosis factor alpha (TNFalpha). Hydrophilic GD(3) and lipophilic GM(3) selectively bound rotavirus particles prepared from a rhesus strain and its mutant. A GS fraction in IBM showed a GM(1)-specific binding to cholera toxin subunit B (CTB). IBM serum (IBMS) was a rich source of LBSA (420 nmol/g proteins). In summary, improved methodology led to increased LBSA recovery and isolation of additional and bioactive milk GS. Human and Italian buffalo milk had similar CTB binding, and both had increased polysialo-GS compared to cows milk. The toxin binding properties of buffalo milk GS, and the anti-inflammatory activity of the lipophilized GS fraction could be important for developing innovative food applications, as well as the subject of future research.