Breastfeeding babies ‘helps prevent viral infection’ in the first months after birth

Babies who are breastfed in infancy carry fewer harmful viruses in their guts than those fed exclusively on bottle milk, a study claims. 

Scientists studied the first stools of 20 babies aged up to four days and a separate group of 124 babies aged between one and four months. 

Evidence from the faecal matter found even a mixed diet of breast and formula milk strongly inhibits the build-up of viral populations in the infant gut. 

Less than one in ten (nine per cent) of four-month-old babies given breast milk – or a combination of breast and bottle feeds – carried viruses.

However, 30 per cent of infants fed only on formula milk had viruses at this age.

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Dr Frederic Bushman, who led the research from the University of Pennsylvania, says: ‘These findings can help us better understand why some babies get sick and develop life-threatening infections in their first months of life. 

‘Breastfeeding is valuable in supporting infant health. Our data and other work suggests that some breastfeeding is better than no breastfeeding.’

Researchers measured the numbers and types of viruses in the first stool – meconium – and subsequent stools of newborns in the United States and Botswana 

Genome sequencing and other virus-specific tools helped the scientists learn which viruses were present in the childrens’ guts.  

Viruses found included those that can cause stomach complaints.

At birth, babies had little or no signs of viral colonisation but by one month old, both bacteria and viruses could become well-established.

Around one billion viruses were found per gram of gut contents, and the majority of the first wave were predators that piggyback on the first bacteria.

But by four months of age the viruses inside babies include those seen in adults and are able to replicate in human cells and have the capacity to cause illness.

Breastfeeding is thought to suppress this process and protect the baby from infection, but researchers do not yet fully understand why.  

However, the study authors, writing in Nature, said factors in breast milk likely to fight viruses include antibodies from the mother, sugars and proteins. 

Similar benefits for breastfeeding were observed in infants living in both the US and Botswana.

However, four-month-old babies in the African country were more likely to have potentially-harmful viruses in their stools than US children.  

‘Location of the mom and baby seems to play a role, probably due to the kind and number of microorganisms babies are exposed to environmentally,’ said Dr Guanxiang Liang, first author on the study.  

‘Nevertheless, Botswana-born babies still seemed to benefit from breastfeeding, whether exclusively or in addition to formula consumption.’

The study suggests exclusive or partial breastfeeding protects babies from infection, including from viral gastroenteritis, which results in diarrhoea and vomiting.

In the UK, rotavirus – a stomach bug which hits babies and young children – is the most common cause of gastroenteritis.

Acute gastroenteritis is a leading cause of infant death around the world, killing 600,000 to 875,000 babies and children each year.  

UK health policy aims for every baby to be breastfed, if possible, up to the age of six months, but the rate currently falls far short of this.

Between 46 and 48 per cent of mothers totally or partially breastfeed in England by the time their baby is six to eight weeks old,.

Rates by the age of six months are much lower than in many other countries in Europe.

Only 34 per cent of UK babies are receiving some breast milk at this age, compared with 49 per cent in the US and 71 per cent in Norway, a 2016 study found.

Research has shown breastfed babies are less likely to be victims of sudden infant death syndrome, get leukaemia, become obese or suffer heart disease in adulthood.

Experts say breastfeeding also offers health benefits for mothers, including helping to reduce the risk of breast cancer.