Being bullied at school could raise the odds of having a heart attack as an adult.
A study found that men and women who had been victims of bullying as children had higher levels of a blood protein linked to heart attacks and strokes.
However, the reverse was true of the bullies. They had made less of the suspect compound than others.
The researchers analysed data collected from almost 1,500 people during childhood, throughout their teenage years and into adulthood.
This included blood samples and interviews about their experience of bullying.
Levels of C-reactive protein, which is linked to a host of health problems, including heart attacks and strokes, rose with age.
However, they were highest in those who had been bullied as children. And the more they had been bullied, the more C-reactive protein they made.
Those who did the bullying had the lowest levels – lower even than those who had no involvement in bullying, the journal Proceedings of the National Academy of Sciences reports.
Researcher Dr William Copeland, of Duke University in North Carolina, said: ‘Enhanced social status seems to have a biological advantage.
‘However, there are ways children can experience social success aside from bullying others.’
He added that bullying can be added to poor nutrition, lack of sleep and other factors known to affect C-reactive protein levels.
A recent British study found those bullied as children were more likely to have poor mental and physical health 40 years later, aged 50.
They were also less likely to be in a relationship and less happy with life.
The researchers from the Institute of Psychiatry at King’s College London, said: ‘We need to move away from any perception that bullying is just an inevitable part of growing-up.
‘Teachers, parents and policy-makers should be aware that what happens in the school playground can have long-term repercussions for children.’