Bacon lovers beware! Cured meats may triple likelihood of manic behavior

BALTIMORE — Hold the bacon! If you are a fan of beef jerky, salami, hot dogs and other cured meats, you may be putting yourself at risk for manic episodes, according to a new study.

Researchers at the Johns Hopkins University School of Medicine have discovered an apparent link between consumption of nitrate-cured meats and hospitalization for mania, an elevated mood characterized by hyperactivity, euphoria and insomnia.

Manic episodes, which are associated with bipolar disorder and schizoaffective disorder, may last for weeks or months and can lead to delusional thinking and risk-taking behavior. Researchers seeking to find what factors, other than genetics, cause these abnormal mood states were surprised to find a peculiar dietary link.

“We looked at a number of different dietary exposures and cured meat really stood out,” says lead author Robert Yolken, a professor of neurovirology in pediatrics with the university, in a statement. “It wasn’t just that people with mania have an abnormal diet.”

Researchers collected 10 years of demographic, health and dietary data on 1,101 adults aged 18 through 65, some with and some without psychiatric disorders. The authors were originally hunting for a relationship between psychiatric disorders and exposure to food-transmitted viruses when the nitrate connection was made. When researchers studied patient records, they were taken aback to find that people hospitalized for mania had a history of eating cured meats about 3.5 times higher than the group without a psychiatric disorder.

Nitrates, used as preservatives for cured meats, have been associated with cancers and neurodegenerative diseases. Researchers now wondered about a possible manic connection.

Intrigued by the nitrate link, this same group of researchers carried out dietary experiments on rats. Rats were divided into two groups, with one group eating a normal rat chow diet and the other receiving the normal diet plus the equivalent of a hot dog or a snack-size portion of beef jerky every other day. “We tried to make sure the amount of nitrate used in the experiment was in the range of what people might reasonably be eating,” says Yolken.

Researchers found that the nitrate-eating rats developed mania-like hyperactivity and irregular sleeping patterns within two weeks after nitrates were added to their diet. They also had different gut bacteria in their intestines and some brain differences that might be related to bipolar disorder.

“There’s growing evidence that germs in the intestines can influence the brain,” adds Yolken. “And this work on nitrates opens the door for future studies on how that may be happening.”

Researchers caution that their findings do not prove a direct cause and effect between eating cured meats and developing mania. Chomping down on the occasional hot dog is not going to produce a manic episode in most people. But cured meats do seem to be one factor among several that might tip the scales toward mania and bipolar disorder.

Because of the limits of this study, researchers want to see a more definitive study that establishes time frames and quantities of cured-meat consumption.

“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,” says Yolken.

The full study was published in Molecular Psychiatry.