What you eat affects the way you feel, both physically and mentally, and if you're someone who enjoys snacking on beef jerky from time to time, you should take note. Beef jerky with nitrates added was linked to a host of concerning mental changes, including mania in humans and altered behavior and brain gene expression in rats.1
Beef jerky might seem like an obscure topic for a scientific study, but it's been growing in popularity in recent years. Sales of meat snacks increased 3.5 percent from 2016 to 2017 to reach nearly $3 billion in sales. That growth rate is more than twice that seen for potato chips over the same period,2 likely because snackers are increasingly looking for more health conscious, nutritious choices.
Beef jerky, while far from a health food (especially in most of its commercial forms), is high in protein, making it a go-to choice for people looking to cut down on processed carbs. There are a number of reasons why you may want to rethink this "healthy" snack, however, starting with its potential effects on your mental health.
Could Beef Jerky and Other Processed Meats Cause Mania?
Mania is a neuropsychiatric condition that causes hyperactivity, insomnia and feelings of euphoria. It's often seen as part of mental conditions such as bipolar disorder and schizoaffective disorder, and although it may have a genetic component, environmental factors are also thought to play a role. During a manic episode, delusional thinking and risk-taking behavior may occur, leading to multiple hospitalizations.
Up to 3 percent of Americans are estimated to have bipolar disorder, costing $25 billion a year in direct health care costs.3 The featured study, published in Molecular Psychiatry, reviewed health records from more than 1,000 people, some with psychiatric disorders and some without. People who were hospitalized with mania were 3.5 times more likely to have eaten cured meats than people without a history of psychiatric disorders.
Study author Dr. Robert Yolken, the Theodore and Vada Stanley distinguished professor of neurovirology in pediatrics at Johns Hopkins University School of Medicine, said in a statement, "We looked at a number of different dietary exposures and cured meat really stood out … It wasn't just that people with mania have an abnormal diet."4
The researchers also fed rats meat preparations with added nitrates, namely "store-bought, nitrate-prepared beef jerky, which led to mania-like hyperactivity and irregular sleeping patterns in the animals, along with alterations in brain pathways that have been implicated in human bipolar disorder and changes in intestinal microbiota. The same results occurred when the rats were fed rat chow with nitrates added, while rats that ate nitrate-free beef jerky or rat chow with no nitrates displayed no such changes.
The amount of nitrate the rats consumed was equivalent to what a human might consume by eating one beef jerky stick or hot dog daily. "Future work on this association 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," Yolken said.5
"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," says Khambadkone. "Our results suggest that nitrated cured meat could be one environmental player in mediating mania." Seva Khambadkone, of Johns Hopkins department of psychiatry and behavioral sciences, also worked on the study, adding:6
"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. Our results suggest that nitrated cured meat could be one environmental player in mediating mania."
Why Might Nitrate-Laden Processed Meats Disrupt Your Mental Health?
Nitrates in cured and processed meats such as beef jerky, bacon and hotdogs are known to be carcinogenic and have also been implicated in neurodegenerative diseases. The nitrates in processed meats are turned into nitrites by bacteria in your mouth, and then into carcinogenic nitrosamines when they reach your stomach.7
As explained by Gunter Kuhnle, professor of food and nutritional sciences at the University of Reading, U.K., "What makes processed meats so ideal for forming N-nitroso compounds is that they have a combination of nitrite and proteins from the meat. And the meat's heme seems to help convert them into N-nitroso compounds."8
"Nitrosamines mediate their mutagenic effects by causing DNA damage, oxidative stress, lipid peroxidation and proinflammatory cytokine activation, which lead to increased cellular degeneration and death," researchers wrote in the Journal of Alzheimer's disease.9 These same processes also contribute to neurodegeneration that could influence your mental health. Nitrosamines are also linked to inflammation, a key player in cancer and other diseases that has also been implicated in manic episodes.
"We think the key is probably inflammation," Yolken said in a news release.10 Gut microbiota is another primary suspect, as the rats that ate nitrates had different bacterial strains in their guts than the other animals. "There's growing evidence that germs in the intestines can influence the brain," says Yolken. "And this work on nitrates opens the door for future studies on how that may be happening."11