Eating processed meat could raise someone's risk of having a manic episode.
A study of more than 1,000 people, including those with psychiatric disorders, found people who had consumed processed meat were three and a half times more likely to have been hospitalised for mania.
Manic episodes, where people become hyperactive, euphoric and cannot sleep, affect one to two in 100 people, including presenter Stephen Fry and Hollywood actress Carrie Fisher. They are part of bipolar disorder, which used to be called 'manic depression'.
Researchers at Johns Hopkins University asked people if they had ever eaten dry, cured meats.
While salami and prosciutto were not linked to mania, cured 'meat sticks' were linked to an increased chance of hospitalisation.
Eating processed meat could raise someone's risk of having a manic episode
They say nitrates, used as meat preservatives, may affect the brains and gut bacteria of people who eat them. Nitric oxide is found in higher levels within the blood of people with bipolar disorder.
Lead author Dr Robert Yolken, from Johns Hopkins University School of Medicine, said: 'Future work on this association could lead to dietary