Smacking children may put them at greater risk of cancer, heart disease and asthma later in life, a controversial study has suggested.
Psychologists asked adults with the diseases if they had been verbally or physically abused as children and found they were more likely to say they had been than healthy adults.
The team from Plymouth University said the stress caused by the smacking or shouting in a child's early years may lead to biological changes which predisposes to disease.
Other studies have also suggested that severe trauma in childhood such as physical or sexual abuse may lead to an elevated risk of chronic diseases later.
However experts said it is difficult to rule out other factors such as poverty and social isolation which are often linked to physical and verbal abuse in childhood and could cause disease later in life.
The research team asked 250 healthy adults in Saudi Arabia about their childhood and compared the answers to 150 adults with heart disease, 150 with cancer and 150 with asthma.
They were asked whether and how often they had been beaten and subjected to verbal abuse as children.
Those who had cancer were 70 per cent more likely to have been beaten as a child compared to the healthy group.
Those with cardiac disease were 30 per cent more likely and those with asthma 60 per cent more likely.
Professor Michael Hyland, from the University’s School of Psychology, who led the study said: “Early life stress in the form of trauma and abuse is known to creating long term changes that predispose to later disease.
"But this study shows that in a society where corporal punishment is considered normal, the use of corporal punishment is sufficiently stressful to have the same kinds of long term impact as abuse and trauma.
“Our research adds a new perspective on the increasing evidence that the use of corporal punishment can contribute to childhood stress, and when it becomes a stressor, corporal punishment contributes to poor outcomes both for the individual concerned and for society.”
Smacking a child so hard it leaves a mark may lead to a criminal prosecution in Britain carrying a maximum five-year prison sentence.
Prof David Spiegelhalter, Winton Professor Of The Public Understanding Of Risk at the University of Cambridge, said: “I would be very cautious about over-interpreting these results.
"For example, the healthy group are taken from administrators and nurses at the hospital treating the patients, and so are likely to differ in many ways from the ill people. The controls reported less beating and insulting as children, so maybe not being beaten encourages people to enter a caring profession, rather than protecting them from disease?”
Dr Andrea Danese, Clinical Lecturer in Child & Adolescent Psychiatry at the Institute of Psychiatry, King's College London, said: “This research adds to the growing body of research linking childhood maltreatment to later disease. It is possible that child maltreatment may not only affect risk for mental illness but also contribute to risk for medical illness, such as asthma, cancer, and cardiac disease.
“This may have major implication for the way we understand the origins of disease and, thus, for disease prevention.
"However, the evidence is largely based on retrospective reports of childhood maltreatment. In other words, instead of assessing maltreatment in childhood years and following children for years until they reach adulthood to check their health status, often researchers have asked adult people with or without disease to report on their memories of maltreatment in childhood.
"The claims may therefore be biased or overstated, because ill people may be more likely to report unhappy childhood.