Researchers at the University of Southampton believe the weaning technique could show the immune system solids are safe and make the development of allergies less likely.
Lead researcher, Kate Grimshaw, told HealthDay: "Mothers should continue to breastfeed beyond introducing solids into the diet so the immune system can benefit from the immunological factors in breast milk that educate the immune system.
"My theory was that if food allergens - those things that infants actually become allergic to - aren't there at the same time as the breast milk, the breast milk can't educate the immune system."
Dr Grimshaw believes it is important to wait until a baby is 17 weeks before introducing solids as introducing them before this age is associated with a higher risk of allergies.
However, the research has been criticised as 'just speculation' by other experts. Dr Vivian Hernandez-Trujillo, from Miami Children's Hospital, said: "Unfortunately, we still don't have all the answers when it comes to food allergies. It appears that breastfeeding may be protective, but we still don't know why."
The NHS currently recommends that babies should be introduced to solid foods when they are about six months old.
It says babies should also be given milk - either breast milk or formula milk - while they are being introduced to solids.
Dr Grimshaw studied the diets of 41 babies who went on to develop allergies and compared them to the diets of 82 children who did not.
She found that the children who developed allergies had been given solid foods earlier than those who did not.
She also noticed these children were less likely to be receiving breast milk at the point at which they were introduced to cow's milk.