Peter Roy-Byrne, MD reviewing Khambadkone SG et al. Mol Psychiatry 2018 Jul 18.

Although there is a significant genetic contribution to bipolar illness, environmental factors, including diet, are thought to be important. These researchers surveyed the dietary history (foods “ever eaten”) of a broad group of psychiatric patients receiving hospital or outpatient care (bipolar mania, 217 individuals; bipolar depression, 91; major depression, 79; schizophrenia, 371) and 343 healthy controls.

A history of eating nitrate-cured meat products specifically was associated with being in the mania group. A subgroup of 42 patients with mania and 35 controls were asked about the type of cured meat products eaten; meat sticks, beef jerky, and turkey jerky were specifically implicated.

In follow-up experimental studies of rats, a meat diet with added nitrates produced both overall hyperactivity and hyperactivity to novel stimuli. The diet was also associated with expressed gene dysregulation involving serotonin, nuclear factor signaling, and sphingosine-1-phosphate signaling and with increases in small-bowel bacteria species previously linked to cognitive and behavioral alterations in animals.