Monday 3 September 2018

Nitrated meat products related to manic behaviour

Nitrated meat products related to manic behaviour
In the past, controversy surrounded nitrates due to a link with neurodegenerative disorders. Recent research published in “Molecular Psychiatry” demonstrates that nitrated meat products can contribute to manic behaviour. 

Nitrites or nitrates are usually added to meat products as they act as preservatives and to prevent discolouration. However, it has been found that nitrated meat (beef jerky, salami, hot dog sausages) could contribute to manic episodes inherent in mood disorders. These periods are characterised by hyperactivity, euphoria and insomnia. Mood disorders of this type, which can last for weeks or months, occur frequently in people who suffer from bipolar disorder. 


Psychiatric disorders and contaminated meat

The researchers were initially looking for psychiatric disorders that are associated with viral  infections as a result of contaminated meat. But by chance they found themselves on a different track. To this end, a large-scale analysis was performed involving more than 1,100 adults in the age category 18 to 65 years. A portion of the study population suffered from a psychiatric disorder. 
It was noteworthy that people who often ate nitrated meat were admitted to hospital more frequently as a result of manic episodes than people who had rarely or never eaten processed meat. It must be emphasised that this concerns processed nitrated meat. Expressed in figures, it was found that the meat-eaters were more than three times more likely to be admitted than people with no psychiatric disorders. The same researchers then commenced an animal study. 


Disrupted sleep and hyperactivity

A group of rats was divided into two groups. One half ate conventional rat food and, every other day, the other half were given (in additional to normal rat food) a piece of nitrated meat. After two weeks, the rats who ate the processed meat demonstrated a disrupted sleeping pattern and hyperactive behaviour. Subsequently, additional experiments were performed with nitrate-free dried meat to demonstrate that nitrate and nothing else could be the culprit. Rats who ate nitrate-free meat were found to behave identically to the control group (rodents) who only consumed rat food. It was once again found that the animals who ate nitrated meat displayed sleeping disorders and hyperactive behaviour. 
The researchers then gave the rats food to which nitrate was or wasn’t added. Human quantities were also taken into account. Therefore, in this experiment the amount of nitrate was at the same level as the amount that people would consume. This time the researchers analysed the gut flora of the rats and discovered that animals who had eaten food treated with nitrate had different gut flora. Different molecular pathways (communication routes) were also found in the brains of these animals, that are associated with bipolar disorders. Evidently the bacteria in the intestines have an impact on the brain.  

Does it also work like that in people?

The research team warns that it is too early to draw clinical conclusions. Plus the occasional consumption of processed meat will not lead to manic behaviour or a bipolar disorder. Principal researcher Robert Yolken, affiliated with the John Hopkins University School of Medicine, emphasises that manic behaviour is part of complex psychiatric disorders, where biological (genetic) and environmental factors might be in play. Exposure to nitrated meat is one of the factors that contributes to mania. 
The Yolkens group recently also published the results of an independent study that demonstrates that people with a bipolar disorder benefit from using probiotics that can change the composition of the gut flora following a manic episode. There is overwhelming proof that bacteria in the intestines affect the brain. Research into nitrates opens the door for future studies into the impact of environmental factors on the brain through the gut flora.


Khambadkone SG, Cordner ZA, Dickerson F, Severance EG, Prandovszky E, Pletnikov M, Xiao J, Li Y, Boersma GJ, Talbot CC Jr, Campbell WW, Wright CS, Siple CE, Moran TH, Tamashiro KL, Yolken RH. Nitrated meat products are associated with mania in humans and altered behavior and brain gene expression in rats. Mol Psychiatry. 2018 Jul 18. doi: 10.1038/s41380-018-0105-6. [Epub ahead of print] PubMed PMID: 30022042.

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