Countries recovering from war and with growing numbers of people with illnesses such as high blood pressure and diabetes are open to exploitation by alcohol, tobacco and food companies, experts have said.
A lack of intervention by the state means private firms are stepping in to bridge the gap when it comes to non-communicable diseases, according to the researchers.
They warn that people in post-conflict countries can suffer mental health issues resulting from exposure to violent and traumatic events, being forced to move, poverty, uncertainty and isolation. And they say less attention has been paid to how this environment increases the risk of other health problems.
Writing in the Bulletin of the World Health Organisation (WHO), Bayard Roberts and Martin McKee, of the London School of Hygiene and Tropical Medicine (LSHTM), and Preeti Patel, of King's College London, said: "First, high levels of psychological distress contribute to harmful health behaviours, such as hazardous drinking and increased smoking, which in turn increase the future burden of non-communicable diseases.
"Second, post-conflict countries are also commonly characterised by expanded urbanisation, also associated with increased alcohol and tobacco use, as well as higher levels of obesity and reduced physical activity.
"Third, tobacco, alcohol and food companies often take advantage of weakened post-conflict trading systems."
The burden of non-communicable diseases is growing. The researchers said the years of life lost from non-communicable diseases in Libya is three times higher than from those diseases that are easily spread.
Similar patterns can also be seen in conflict-affected countries in the Balkans and Sri Lanka, and high blood pressure is largely untreated in Iraq.
"This toxic combination of stress, harmful health behaviours and aggressive marketing by multinational companies in transitional settings requires an effective policy response but often the state has limited capacity to do this. For example, Afghanistan has no national policy, strategy, targets or co-ordinating body for non-communicable diseases."
The researchers said this opened up an opportunity for big companies to exploit conditions. "This policy vacuum provides an open door for multinational companies to influence policies in ways that undermine efforts to control tobacco and alcohol use or improve unhealthy diets in transitional countries."