Breastfed babies have a lower risk of stomach problems
Babies should be fed just breast milk for six months, the government has recommended.
Breastfeeding provides all the nutrition an infant needs and provides long- and short-term health benefits for both mother and baby.
"Breastfeeding is the best form of nutrition for infants," the department of health said on Monday.
"Exclusive breastfeeding is recommended for the first six months (26 weeks) of an infant's life as it provides all the nutrients a baby needs."
The Department of Health's recommendation brings it into line with the World Health Organisation, and marks the beginning of national breastfeeding awareness week.
The UK has one of the lowest breastfeeding rates in Europe, with nearly a third of UK babies never being breastfed. Nine of ten mothers stop breastfeeding their babies after only six weeks.
Breastfeed babies have a lower risk of gastro-enteritis and respiratory and ear infections. They may also have a lower risk of becoming obese later in childhood.
Breastfeeding for the first six months provides the best start for babies
Public Health Minister
For mothers, there is some evidence that long-term breastfeeding may help them lose excess weight gained during pregnancy.
The longer a woman breastfeeds, the lower the risk of developing pre-menopausal breast cancer.
Figures from 2000 suggest only 70% of mothers in England and Wales breastfeed, 63% in Scotland and 54% in Northern Ireland.
The recommendation has been supported by the Community Practitioners and Health Visitors Association and the Royal College of Midwives.
Public Health Minister Hazel Blears said: "We want to give a clear and consistent message to mothers, health professionals, and the general public.
"Breastfeeding for the first six months provides the best start for babies.
"It establishes a foundation for improving short and long-term health and in so doing can help to reduce health inequalities," she said.
"We want to support women in their decision to breastfeed and help them continue to do so."
Public support needed
The guidance was welcomed by leading childbirth charity, the National Childbirth Trust, which called on the public to support breastfeeding mothers.
NCT policy research officer Rosemary Dodds said: "The evidence is clear that breastfed babies do not generally need to start on solid foods before about six months.
"We are encouraging families and health professionals to have more confidence in breastfeeding.
"It is vital that this confidence is conveyed to mothers so that they feel well supported."
An advertising campaign has begun to encourage people to support breastfeeding mothers.
In Britain last year, a plan to allow women MPs to breastfeed in the House of Commons chamber was blocked by Speaker Michael Martin.