Adults who were breast-fed as infants are less likely to suffer from depression, according to a German study.
The researchers studied 52 people being treated for depression with an average age of 44.
The participants were considered to have been breast-fed if they'd been nursed for two weeks or more.
Celeb post pregnancy diets
When the researchers compared them with 106 people without mental health problems, they found 73 percent of people without depression had been breast-fed, while only 46 percent of people who had depression had been breast-fed.
The scientists admit there is no cause-and-effect relationship between breast-feeding and avoiding depression because many factors could contribute to depression.
The amount of time an infant is breast-fed does not appear to have an effect on their mental health.
According to MyHealthNewsDaily, mothers who breastfeed are more likely to provide a loving environment for their child, which could reduce their chance of suffering depression later in life. Breastfeeding also causes a mother to release the hormone oxytocin, which calms the mother and baby.
The researchers also believe breastfeeding can lower the risk of hypertension which is associated with depression.
Dr Jennifer James, a senior lecturer in nursing and midwifery at RMIT University, told ninemsn the study is limited.
"It's very difficult to study this over a long period of time –– it costs an enormous amount of money and resources," she said.
"The study is saying that there appears to be protection from depression, but the limitations of the study are the biggest worry. We can't really take a strong message from it."
However Dr James said other, more comprehensive studies have found that breastfeeding can offer protection against depression for adolescents.
"It's more difficult to find an association into middle adulthood and middle age, purely because it's so difficult to measure," she said.
But Dr James said obvious mental health benefits come from breastfeeding.
"If you have a well-attached mother and baby it lasts most of life," she said.
Celebs who bounce back after pregnancy
"If we look at the close physical contact women have with their babies every time they breastfeed –– there's eye contact, skin to skin contact, talking to each other and interacting and responding all the time. Every time a woman breastfeeds she gets a release of a hormone called oxytocin, which has this wonderful effect of calming the mother and the baby."
The report was published in the journal Psychotherapy and Psychosomantics.