Babies born during famine are at higher risk of schizophrenia, a study has found.
Malnutrition can harm mental as well as physical health
The Chinese famine of 1959-1961 increased the risk of schizophrenia in later life from 0.84% to 2.15%, Shanghai researchers calculated.
It is not clear whether it is lack of food in general or a lack of specific nutrients while in the womb that is important.
The work appears in the Journal of the American Medical Association.
It supports the findings of previous study in Holland where schizophrenia risk was doubled among children conceived during war-related food shortages in 1944-1945.
In the China study, the team from the Shanghai Jiao Tong University compared the rates of schizophrenia among those born before, during and after the famine years in the Wuhu region, which currently has a population of 62 million.
During the famine, the birth rate for the area decreased by around 80%.
However, among the babies that were born, more went on to develop schizophrenia as adults than the babies born during non-famine years.
Schizophrenia risk increased from 0.84% in 1959 to 2.15% in 1960 and 1.81% in 1961.
Based on the trends found they believe the critical time of famine is during the first three months of pregnancy.
Early embryo damage
Dr David St Clair and his team said there were many possible explanations for this.
It might be that lack of food adversely affected the developing embryo's brain, thereby increasing the risk of schizophrenia.
Alternatively, it might be that certain essential nutrients were missing from the pregnant women's diets, causing harm to the baby, similar to the way that folic acid deficiency can lead to neural tube defects in unborn children.
Some researchers have already shown a link between folic acid and schizophrenia.
Another possibility is that during the famine the mothers ate more food substitutes that could have been toxic to the baby.
For example, in China the women ate tree bark and green algae grown at home in vats of urine.
In Holland, people ate tulip bulbs during the famine.
It is also possible that women carrying genes for schizophrenia were more likely to conceive and have successful pregnancies than other women, at a time when the birth rate was going down due to famine.
The schizophrenia genes might confer some survival benefit, said the researchers.
However, there was no difference in the number of family members with schizophrenia among the babies who went on to develop schizophrenia before, during and after the famine, suggesting this was not the most likely cause of the trend.
Dr Richard Neugebauer from the New York State Psychiatric Institute in the US said the findings raised the possibility of public health interventions to prevent schizophrenia.
"It raises the possibility of primary prevention strategies for this most devastating of psychiatric disorders," he said.
Depending on the cause, better nutrition or supplements of specific micronutrients such as folic acid might help, he said.
Paul Corry from the mental health charity Rethink said: "Good nutrition is central to good physical and mental health.
"Some foods can contribute to cause illness while the absence of certain minerals and vitamins and the addition of additives can both cause mental illness and hinder recovery."
He said there was strong evidence that low folic acid was associated with depression and schizophrenia.
"While we welcome any new research or progress into understanding the causes of schizophrenia it would need to be checked before it would make a difference to the thousands of people living with severe mental illness in the UK.
"In the meantime, reaching people early with the right care and treatment is the best way of recovering a meaningful and fulfilling life," he said.