Breastfed babies may be at greater risk of developing food allergies, according to research.
Japanese scientists found infants who were exclusively breastfed were more than twice as likely to be treated for a food allergy.
The experts, who analysed how 46,000 infants were fed, say breastfeeding mothers may be more likely to delay weaning.
Research suggests children are more likely to develop allergies against certain food proteins if they are not exposed to them ‘early enough’.
Breastfed babies may be at greater risk of food allergies, research suggests (stock)
However, the Okayama University researchers found only the babies without eczema faced an increased risk of a food allergy.
The infants with the common skin condition who were breastfed were 36 per cent less likely to develop a food allergy.
Breastfeeding is thought to boost ‘oral tolerance’ in youngsters with ‘skin barrier dysfunction’, according to the researchers led by Dr Naomi Matsumoto.
It has long been known that ‘breast is best’, with evidence suggesting a mother’s milk protects against infections, obesity and diabetes, the scientists wrote in the journal Allergology International.
The World Health Organization recommends all babies are exclusively breastfed for six months.
When it comes to its effect on food allergies, however, studies have thrown up mixed results.
These ‘inconsistencies’ may have come about due to past scientists not considering how eczema raises the risk of food allergies, the team wrote.
This is thought to occur through ‘percutaneous sensitisation’, a recent theory that food proteins can cross the skin.
To learn more, the team analysed 46,616 children who took part in the Longitudinal Survey of Newborns in the 21st Century.
Questionnaires were sent to the parents of all babies born in Japan between January 10 and 17 or July 10 and 17, 2001.
The infants were then divided into three groups according to how they were fed; exclusive breast feeding, partial breast feeding including the colostrum, and formula only.
Colostrum is the fluid a new mother’s breasts produce in the first few days. It is a very concentrated feed, rich in protein, immune-fighting substances, antioxidants and ‘good bacteria’.
The babies were assessed for allergy-related hospital visits between six months old and either 18 months or five-and-a-half.
Results showed the babies who did not have eczema and were exclusively breastfed were more than twice as likely to be treated for a food allergy.
This is compared to the infants were only given formula.
Among the infants who were partially breastfed, only those with eczema were protected against a food allergy, with their risk going down by 36 per cent.
Although unclear, breastfeeding may protect babies with eczema via the ‘dual allergen exposure hypothesis’.
This states food allergies come about due to an imbalance between skin sensitisation and ‘oral tolerance’.
Babies with this imbalance due to skin barrier dysfunction may benefit from breastfeeding to maintain their oral tolerance, the scientists wrote.
A mother’s breast milk, particularly the colostrum, contains many substances that strengthen an infant’s immune system against allergies.
Why babies without eczema who are exclusively breastfed do not benefit is less clear.
The scientists speculate it may be due to ‘delayed food introduction’. One study showed, for example, babies who are given cow’s milk ‘early’ are less likely to be allergic to it.
The team stress, however, they did not collect information on when the infants started on solid food. Future research is therefore required to confirm this.