A Johns Hopkins Medicine study has revealed that those who were hospitalised for mania were more than three times more likely to have had eaten beef jerky, ham or salami in the recent past and scientists are of the opinion that this could be due to the presence of nitrates that chemicals used to process and cure meats.
Headlines declaring a link between the nitrates in cured meat and bipolar mania - a serious mood disorder characterized by irrational euphoria, erratic behavior, hyperactivity, and insomnia - have been splashed across the news following the publication of a study led by the Johns Hopkins University School of Medicine.
Experiments in rats by the researchers showed that mania-like hyperactivity after just a few weeks on diets with added nitrates. Nitric oxide is found in higher levels within the blood of people with bipolar disorder. Researchers, hence, are looking at diet as a plausible causative factor among other things.
The new study adds to evidence that certain diets and potentially the amounts and types of bacteria in the gut may contribute to mania, the researchers say.
Mania is generally seen in people with bipolar disorder, but can also occur in those with schizoaffective disorder.
Seva Khambadkone, a co-author who worked on the rat experiment, added: '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.
Bipolar disorder affects an estimated one to three percent of the United States population and costs an estimated $25 billion a year in direct health care costs, according to a study in the Journal of Affective Disorders.
"We found that a history of eating nitrated dry-cured meat but not other meat or fish products was strongly and independently associated with current mania", Yolken and colleagues wrote in their report, published in the journal Molecular Psychiatry.
They are part of bipolar disorder, which used to be called 'manic depression'. No other foods had a significant association with any of the disorders.
"We looked at a number of different dietary exposures and cured meat really stood out".
Nitrates have always been used as preservatives in cured meat products and have been previously linked to some cancers and neurodegenerative diseases.
Yolken says future studies could take a more in-depth look at the frequency and volume of nitrate consumption to help researchers understand more about any possible connection between nitrates and mania.
A previous study from Yolken's group showed that mania patients are less likely to be re-hospitalized if they are given probiotics, which can affect gut bacteria. The amount of nitrate was around the same as if a human ate one hot dog or beef jerky stick every day, according to CTV News.