A US study found women who breastfed for more than a year were 10% less likely to develop the conditions than those who never breastfed.
Even breastfeeding for at least a month may cut the risk of diabetes, high blood pressure and high cholesterol.
The research features in the journal Obstetrics and Gynaecology.
The study adds to a growing body of evidence suggesting breastfeeding has health benefits for both mother and baby.
Research has found that breastfeeding reduces a woman’s risk of ovarian and breast cancer and osteoporosis in later life.
And the list of benefits for the baby is long, with breast milk credited with protecting against obesity, diabetes, asthma and infections of the ear, stomach and chest.
The latest US study, by the University of Pittsburgh, focused on nearly 140,000 post-menopausal women.
On average, it had been 35 years since the women had last breastfed – suggesting the beneficial impact lasts for decades.
As well as cutting the risk of heart problems, breastfeeding for more than a year cut the risk of high blood pressure by 12%, and diabetes and high cholesterol by around 20%.
It has been suggested that breastfeeding may reduce cardiovascular risk by reducing fat stores in the body.
However, the researchers believe the effect is more complex, with the release of hormones stimulated by breastfeeding also playing a role.
Researcher Dr Eleanor Bimla Schwarz said: “We have known for years that breastfeeding is important for babies’ health; we now know that it is important for mothers’ health as well.
“Breastfeeding is an important part of the way women’s bodies recover from pregnancy.
“When this process is interrupted women are more likely to have a number of health problems (including heart attacks and strokes).
“The longer a mother nurses her baby, the better for both of them.”
In the UK, the Department of Health recommends exclusive breastfeeding for six months.
June Davison, a cardiac nurse at the British Heart Foundation, said: “Breastfeeding has long been thought to be beneficial to baby and mother.
“This research suggests that it might have also have heart health benefits for mum too.
“However, it only showed an association between breast feeding and these health benefits. We will need further research to understand why this is the case.”
Ref: [ BBC news – http://news.bbc.co.uk/2/hi/health/8008678.stm ]