Human milk contains oxylipins involved in infant development. Although oxylipins have been identified in whole or skim milk, their localization within human milk cream, cell, and skim fractions is not known. This study determined the distribution of free and esterified oxylipins in cream, cell, and skim fractions of human milk. Out of 72 oxylipins probed by mass-spectrometry, 42, 29, and 41 oxylipins (free or bound) were detected in cream, cell, and skim fractions, respectively. Over 90% of free and bound oxylipins were derived from linoleic acid in all milk fractions. Other oxylipins were derived from n-6 arachidonic acid and dihomo-gamma-linolenic acid, and n-3 alpha-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid. Free oxylipins were more abundant in skim milk (59.9% of total oxylipins) compared to cream and cell pellet, whereas esterified oxylipins were most abundant in milk cream and cell pellets (74.9-76.9%). The heterogenous distribution of oxylipins in different fractions of human milk may regulate the guided release of these bioactive signaling molecules within infants.

Objectives Very little is known about dietary carbohydrate and intestinal microbe interactions during the introduction of solid foods in exclusively breastfed infants. The objective of the UC Davis IMiND study is to discover the relationships between plant-derived complementary foods commonly used in the early weaning period and the gut microbiome in a prospective feeding-trial in exclusively breast milk-fed infants. Methods In a randomized, crossover study, 6-month old, exclusively breastfed infants (n = 99) entered a 7-day lead-in period of exclusive breast milk, followed by 7 days of either study food (pear or sweet potato) plus breast milk. This was followed by a 4-day washout period of exclusive breast milk, then 7 days of the alternate study food, followed by a 4-day follow-up period of exclusive breast milk. The infant gut microbiome was measured by 16 s rRNA amplicon sequencing (n = 39). Fecal monosaccharides and short chain fatty acids were measured in a subset of mother-infant dyads (n = 20) by liquid chromatography-mass spectrometry. Results There was no significant difference in gut alpha diversity (Shannon index) but a significant difference in beta diversity (unweighted UniFrac, P = 0.03, R,2 = 0.02) between pre- and post- first food. Free fecal monosaccharide composition was similar across all feeding periods. Total bound fecal monosaccharides, including arabinose and xylose were 2-fold higher in response to pear consumption compared with the other feeding periods (P < 0.05). Infant fecal lactic acid was lower and succinic acid was higher by 2-fold during pear consumption compared with all other feeding periods (P < 0.05). Conclusions The change in gut microbiome beta diversity suggests a change in microbial composition with the introduction of solid foods despite the unchanged alpha diversity. The change in fecal short chain fatty acids in response to pear consumption suggests a change in microbial metabolism. These effects may be explained by the appearance of undigested, bound glycans in the colon during pear consumption. These data suggest a novel approach in using chemical analysis to document the diversity and complexity of dietary carbohydrates during weaning that influence gut microbial metabolism. Funding Sources Mongolia Mengniu Dairy (Group) Company Ltd. funded this research but had no part in the analysis or interpretations of the study findings.

Objectives Streptococcus salivarius (S. salivarius) K12 supplementation in children and adults has been found to reduce the risk of recurrent pharyngitis, tonsillitis, otitis media caused by group A streptococci. The protection of S. salivarius K12 supplementation may in part result from its production of lantibiotic bacteriocins salivaricin A and B. Yet, studies have not reported the effect of supplementation on oral S. salivarius K12 levels or the broader salivary microbiome. The objective of this clinical trial was to determine how supplementation with S. salivarius K12 influences the oral microbiome. Methods In a double-blind, placebo-control, prospective trial, 24 healthy adults were randomized to consume a probiotic powder (PRO) containing 7.8B CFU of L. acidophilus, 8.25B CFU of B. lactis, and 2B CFU of S. salivarius K12 (n = 12) or a placebo-control powder (CON) (n = 12) for fourteen consecutive days. Saliva samples were collected at baseline, at the end of the fourteen-day supplementation period and two weeks post-supplementation. Oral S. salivarius K12 and total bacteria were quantified by QPCR and the oral microbiome was measured using 16s rRNA amplicon sequencing. Results Supplementation with S. salivarius K12 significantly increased salivary S. salivarius K12 by 5 logs compared to baseline for the PRO group (P < 0.0005) and returned to baseline 2-weeks post-supplementation. Compared with the CON group, salivary S. salivarius K12 was 5 logs higher in the PRO group at the end of the supplementation period (P < 0.001). Neither time nor supplementation influenced the oral microbiome. The supplement was well-tolerated. Conclusions Supplementation with a probiotic containing S. salivarius K12 for two weeks significantly increased levels of salivary S. salivarius K12 by 5 logs but had no effect on the overall oral microbiome measured by 16s rRNA amplicon sequencing. Funding Sources Renew Life funded this research but had no part in the analysis or interpretations of the study findings.