Variability of human milk neutral oligosaccharides in a diverse population.

BACKGROUND: A complex array of free oligosaccharides is a distinctive compositional feature of human milk. Although these oligosaccharides have been studied for several years, their variability and distribution have not been systematically studied, and their nutritional and functional roles have not been elucidated. This report describes a study in which a large number of human milk samples were analyzed for the presence and content of nine neutral oligosaccharides. The resultant data were used to probe for distribution trends by donor groups and stage of lactation. METHODS: Milk samples from 435 women residing in 10 countries were analyzed using a simple preparation procedure, gel filtration, and high-performance anion-exchange chromatography. RESULTS: All samples contained structures based on lacto-N-neotetraose and lacto-N-tetraose. This contrasts with the fucosyloligosaccharides tested, none of which was detected in 100% of the samples. Unexpected distribution trends were observed. For example, 100% of the samples from Mexico (n = 156) contained 2'-fucosyllactose, whereas only 46% of the samples from the Philippines (n = 22) contained this structure. Concentration ranges for the analyzed oligosaccharides revealed quantitative and qualitative distribution trends. CONCLUSIONS: The oligosaccharide composition of human milk varied among samples. The geographical origin of the donors was one of the factors that accounted for this variability. This can be explained by genetically determined traits that are not uniformly distributed. Results indicated that further systematic studies are needed to ascertain the effect of other factors, such as lactation stage or diet.

Evaluation of the immunogenicity of protein hydrolysate formulas using laboratory animal hyperimmunization.

The rabbit hyperimmunization model has previously been used to evaluate candidate hypoallergenic protein ingredients. Use of the model has been expanded to include the evaluation of protein hydrolysate formulas. Each formula's immunological reactivity was determined by ELISA measurement of formula-specific rabbit antibody. Animals hyperimmunized with formulas containing extensively hydrolyzed proteins (Alimentum, Nutramigen, and Pregestimil) generated very weak immune responses (< 100 fold antibody increase). Products containing intact or partially hydrolyzed proteins (Similac, Enfamil, Good Start, Beba HA, and Nidina HA) elicited high level (> 10,000 fold increase) immune responses. Immunogenicity results were then compared to measurements of residual antigen content (by inhibition ELISA) and clinical performance. Correlation of formula immunogenicity, antigenicity and clinical performance indicates that the rabbit model is useful for screening "hypoallergenic" formulas to predict allergenic reactivity.