To do so, they examined the health records of more than 1,000 people, aged 18 to 65, with and without psychiatric disorders. Those with psychiatric disorders were patients from the Sheppard Pratt Health System in Baltimore, and those with no history of them were volunteers.
They found that people who were hospitalized for mania were about 3.5 times more likely to have had a history of eating cured meat before hospitalization, compared to the group without a psychiatric disorder. The meats they consumed were injected with nitrates, chemicals used to cure beef jerky, salami, hot dogs and other processed meat snacks.
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"It's clear that mania is a complex neuropsychiatric state, and that both genetic vulnerabilities and environmental factors are likely involved in the emergence and severity of bipolar disorder and associated manic episodes," coauthor Seva Khambadkone said in a statement. "Our results suggest that nitrated cured meat could be one environmental player in mediating mania."
The same researchers also experimented with rats, feeding them normal chow and a piece of store-bought, nitrate-prepared beef jerky. They discovered that the animals who ate the beef jerky showed mania-like hyperactivity after a few weeks, while the rodents who ate nitrate-free foods behaved normally.
Despite the findings, the team noted that it’s too early to make any clinical conclusions. They also said occasional consumption of cured meat is not likely to cause a manic episode in most of the population.
However, they look forward to continuing their investigations.
“Future work on this association,” lead author Robert Yolken added, “could lead to dietary interventions to help reduce the risk of manic episodes in those who have bipolar disorder or who are otherwise vulnerable to mania.”
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