Summary auto-generated
This study examined how different infant feeding methods affect fecal microbiota and physicochemical properties in 47 newborns over six weeks. Researchers compared four groups: exclusively breast-fed infants, infants fed humanized cow milk preparations (Cow and Gate Premium and SMA Gold Cap), and infants receiving breast milk supplemented with cow milk during the first week. Breast-fed infants developed acidic feces (pH 5.1-5.4) with predominant bifidobacteria and an acetate buffer in over 60% of samples within the first four weeks. Exclusively bottle-fed infants had higher fecal pH (5.9-8.2), lower bifidobacterial counts, and higher coliform and putrefactive bacteria. Supplemented infants showed intermediate results with delayed acidification. The acetate buffer appeared in only 20% of supplemented infants during week one, increasing to 60% by week four. The study demonstrates that breast milk's low buffering capacity—due to lower phosphoprotein content—promotes an acidic intestinal environment that favors beneficial bifidobacteria while inhibiting pathogenic organisms including Escherichia coli. Humanized milks with higher buffering capacities failed to establish this protective fermentative flora, resulting in putrefactive bacterial patterns similar to conventional bottle feeding.
Key findings
- Breast-fed infants developed acetate buffer in feces within the first four weeks (>60%), whereas bottle-fed infants showed no acetate buffer during this period
- Breast milk's low buffering capacity maintains fecal pH of 5.1-5.4 with predominant bifidobacteria, while humanized milks with higher buffering capacity resulted in pH 5.9-8.2 and putrefactive flora
- Supplementing breast milk with cow milk preparations in the first week delayed acidification and establishment of fermentative flora, with acetate buffer appearing in only 20% of infants in week one versus >60% of exclusively breast-fed infants
- The differences in volatile fatty acid patterns and bacterial counts reflect the physicochemical properties of each milk type, with breast milk promoting fermentative metabolism and artificial preparations promoting putrefactive metabolism
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Abstract
Faecal specimens from 47 babies were examined each week during the first 6 weeks of life. Thirteen infants received breast milk alone, nine received Cow and Gate Premium milk, 10 received Scientific Milk Adaptation Gold Cap milk, and 15 received breast milk and in the first week of life a supplement of modified cows' milk. An acetate buffer was demonstrated in the faeces of >60% of breast-fed infants during the first 4 weeks of life. No buffer was demonstrated in the faeces of either bottle-fed group over the same period. Only 20% of breast-fed infants receiving a supplement produced an acetate buffer in the 1st week, but this figure increased to 60% by the 4th week. Breast-fed babies produced faeces with a low pH (5·1-5·4), high counts of bifidobacteria and low counts of coliforms, bacteroides and clostridia; with the exception of acetic acid there was a notable absence of most volatile fatty acids from these faeces. Infants fed Premium milk produced faeces with a high pH (5·9-8·0) and a relatively high bifidobacterial count in the 1st week; thereafter no bacterial species predominanted. A wide variety of volatile fatty acids was present in these infants' faeces. Infants fed Gold Cap milk produced faeces with a high pH (6·4-8·2) and a wide variety of volatile fatty acids; the counts of coliform bacilli and putrefactive bacteria were high, whilst counts of bifidobacteria were low. Breast-fed infants who received a supplement in the 1st week produced acid faeces, but the pH was higher than that of infants fed breast milk alone; the bacterial flora was putrefactive for the first 2 weeks but gradually became fermentative, and whilst several volatile fatty acids were detected in the faeces in the 1st week they gradually decreased during the following 5 weeks.