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Antiviral and antibacterial lipids in human milk and infant formula feeds
C E Isaacs1, S Kashyap, W C Heird
1New York State Institute for Basic Research in Developmental Disabilities, Department of Developmental Biochemistry, Staten Island, 10314.
Insights
Gastric aspirates from low birthweight infants showed antiviral and antibacterial properties, regardless of whether they consumed human milk or formula. This activity appears to stem from fatty acids and monoglycerides produced in the stomach.
Area of Science:
- Human milk and infant nutrition
- Microbiology and immunology
- Gastroenterology
Background:
- Human milk and infant formulas are primary nutrition sources for low birthweight (LBW) infants.
- The innate antimicrobial properties of infant nutrition and the infant gastrointestinal tract are crucial for health.
- Limited understanding exists regarding the direct antimicrobial effects of ingested feeds within the infant stomach.
Purpose of the Study:
- To investigate the antiviral and antibacterial activities of gastric aspirates from LBW infants fed human milk or infant formula.
- To determine if feeding type influences the antimicrobial properties of stomach contents.
- To identify the components responsible for observed antimicrobial activities in gastric aspirates.
Main Methods:
- Human milk and two infant formulas were analyzed for antimicrobial activity prior to feeding.
- Gastric aspirates were collected from 21 LBW infants 1-3 hours post-feeding.
- Antiviral and antibacterial assays were performed on unfractionated aspirates and their lipid fractions.
- Specific microbial targets included enveloped viruses, Staphylococcus epidermidis, and Escherichia coli.
Main Results:
- Neither human milk nor infant formula exhibited significant antiviral or antibacterial activity before ingestion.
- Gastric aspirates demonstrated potent antiviral activity against enveloped viruses and bactericidal activity against S. epidermidis and E. coli.
- Lipid fractions of aspirates showed antimicrobial activities comparable to unfractionated samples, irrespective of feeding type (human milk or formula).
- No significant differences in antimicrobial activity were observed between aspirates from infants fed human milk versus formula.
Conclusions:
- The infant stomach environment generates potent antimicrobial substances from ingested milk lipids.
- Intragastric production of monoglycerides and fatty acids from triglycerides appears responsible for these activities.
- Both human milk and conventional infant formulas provide substrates for generating these protective gastric secretions in LBW infants.
Abstract:
Human milk and two infant formula feeds were tested for antiviral and antibacterial activity before being given to 21 low birthweight (LBW) infants; neither was present. When samples were aspirated from the stomachs of the infants within one to three hours of feeding, however, they reduced titres of enveloped virus and also killed both Staphylococcus epidermidis and Escherichia coli. The lipid fraction of the gastric aspirate from an infant who had been given human milk as well as those from four infants who had been given a conventional LBW infant formula feed, showed antiviral and antibacterial activities at least equal to the activities of the unfractionated aspirates. There was no consistent difference in antiviral or antibacterial activity of either the stomach aspirates or the lipid fractions of these aspirates between infants given human milk and those given formula feeds. The antiviral and antibacterial activities of the gastric aspirates seem to result from intragastric production of monoglycerides and fatty acids from the triglyceride content of the ingested feeds.