Breastfeeding 'not always best'
Breastfeeding exclusively for six months is not necessarily best and may put babies off some foods, experts have said.
UK guidelines are for women to breastfeed for the first six months of a baby's life before introducing solids.
But experts led by a paediatrician from University College London's Institute of Child Health said babies could suffer iron deficiency and may be more prone to allergies if they only receive breast milk.
In 2001, the World Health Organisation announced a global recommendation, adopted by the UK in 2003, that infants should be exclusively breastfed for six months.
The experts said the WHO recommendation "rested largely" on a review of 16 studies, including seven from developing countries, which found that babies just given breast milk for six months had fewer infections and experienced no growth problems.
But, another review of 33 studies found "no compelling evidence" to not introduce solids at four to six months, they said, while some studies have also shown that breastfeeding for six months does not give babies all the nutrition they need.
One US study from 2007 found that babies exclusively breastfed for six months were more likely to develop anaemia than those introduced to solids at four to six months, and researchers in Sweden found that the incidence of early onset coeliac disease increased after a recommendation to delay introduction of gluten until age six months.
The authors said exclusively breastfeeding for six months is a good recommendation for developing countries, which have higher death rates from infection.
But in the UK, it could lead to some adverse health outcomes and may "reduce the window for introducing new tastes".
"Bitter tastes, in particular, may be important in the later acceptance of green leafy vegetables, which may potentially affect later food preferences with influence on health outcomes such as obesity."