There are so many things that influence our state of physical & mental being that are interrelated, yet we are relatively unaware of them.
One thing I've been interested in for awhile now is the relationship between the microbiome in the gut & it's effect on not just our physical well-being, but also our mind and emotions.
Psychobiotics: Your Microbiome Has the Potential to Improve Your Mental Health, Not Just Your Gut Heath
When you see the entire human body has a fully-integrated system of trillions of cells, bacteria and other microorganisms, this idea of seemingly separate parts influencing each other seems less far-fetched.
The gut-brain connection results from chemical signals being produced by the microbes in the intestines affecting the nerve endings in the digestive system, which travel up the vagus nerve into the brain.
There is also speculation that gut bacteria digest fiber to produce fatty acids that travel through the blood stream & have an epigenetic effect on gene expression in brain cells.
Whatever the mechanism may be, there is a clear link between what we eat and both our physical & mental state. Getting proper nutrition is not the only dietary concern, but we should also be mindful of how the food we eat could possibly lead to inflammation or other effects that could influence our overall heath.