chemicals that are used to cure meat like beef jerky, salami, hot dogs and
other processed meat snacks. The current study links the consumption of
nitrate-cured meats to developing an abnormal mood state called
that is a
symptom of mental illnesses like bipolar disorder and schizoaffective disorder.
‘A survey of participants admitted in a hospital with or without symptoms of mania revealed that the former group had more than three times the odds of eating nitrate-cured meats than the latter group, indicating that nitrate could be an environmental factor involved in causing the condition.’
"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 lead author Robert Yolken, M.D., the Theodore and Vada Stanley
Distinguished Professor of Neurovirology in Pediatrics at the Johns Hopkins
University School of Medicine.
research team said that their
new study adds to evidence that certain diets and potentially the amounts and
types of bacteria in the gut may contribute to mania and other disorders that
affect the brain.
One to three percent of the
population of the United States is estimated to have bipolar disorder.
Design and Results
colleagues collected demographic, health and dietary data on 1,101 individuals
aged 18 through 65 with and without psychiatric disorders between 2007 and
2017. About half of the participants were female, of which the same number of participants were
Caucasian and 36 percent
identified themselves as African-American.
psychiatric disorder patients were already receiving care at the Sheppard Pratt
Health System in Baltimore and were recruited from there. Individuals without
any history of psychiatric disorders were recruited from announcements that
were posted at local health care facilities and universities in the vicinity.
between 2007 and 2017 were analyzed which revealed that
- The people hospitalized
with mania had a history of eating cured meat before admission which was
approximately 3.5 times higher than the group of people admitted without a
- In people not
hospitalized for mania or in major depressive
disorder, there was no
association between cured meats and a diagnosis of schizoaffective
disorder, or bipolar disorder.
- No significant
association was found with other foods and mania and similar disorders.
which have been previously linked to some cancers and neurodegenerative diseases
could be the suspect in
this case too and could explain the occurrence of mood states such as mania.
collaborated with Kellie Tamashiro, Ph.D., associate professor of psychiatry
and behavioral sciences, and M.D./Ph.D and his students from Johns Hopkins to
get to the bottom of the nitrate-mania association.
Study - Impact of Nitrates
- Kellie Tamashiro and his students did a small experiment on
otherwise healthy rats which were fed every other day. They found that
within two weeks, the group of
rats that received both normal chow and a piece of store-bought,
nitrate-prepared beef jerky showed irregular sleeping patterns and
hyperactivity compared to the group of rats that received only normal rat
- The team wanted to
repeat the experiment and this time asked a Baltimore-based beef jerky
company to create a special nitrate-free dried beef. The result was that
the rats that ate the nitrate-free meat behaved similarly to a control
group whereas the rats that consumed the store-bought, nitrate-prepared
jerky once again showed sleep disturbances and hyperactivity similar to
that seen in patients with mania.
- Similar results were
obtained when they repeated the experiment with a specially formulated rat
chow that either contained added nitrate or no nitrate. The rats which ate
the nitrate-added chow behaved like the rats that had the nitrate-prepared
- The amount of nitrate
that the rats ate on a daily basis when scaled to the size of what a human
ate was equivalent to a beef jerky stick or hot dog.
- Scientists also
analyzed the differences in the gut bacteria of the different rat groups;
rats which ate the nitrate meals had different patterns of bacteria living
in their intestines than the rats that did not get the nitrate-processed
- The two groups of rats
also showed differences in several molecular pathways in the brain that
have been previously implicated in bipolar disorder.
Mania is a complex neuropsychiatric state and more
than one factor is known to cause it. There are genetic vulnerabilities and
environmental factors that are likely involved in the emergence and severity of
bipolar disorder and associated manic episodes.
says that nitrate-cured meat could be
one environmental player in mediating mania
among the multiple factors
involved. The authors say it is still too early to take any clinical messages
from the results.
study by Yolken's group showed that when people with bipolar disorder are given
probiotics (known to change the composition of gut bacteria) after a manic
episode, they are less likely to be rehospitalized in the following six months.
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." Further
studies will focus on how much cured meat boosts one's risk of mania.