There are several studies that say fruits and vegetables are great for mental health.
There are general recommendations that exercise is good for physical and mental health.
The question is how?
But even where specific, they are still bounded by unknowns.
There are psychotropic drugs that relieve some mental conditions. There are synaptic tracks of what they might induce, however, in psychopharmacology there are lots of uncertainties about how they work.
In seeking a path, there are two things to consider, what is happening inside and what the person is experiencing.
Whatever is happening within is immensely complicated, but they build something for external experiences.
Assuming there are three stages for how nutrition and fitness benefits mental health: input, hidden and output.
The hidden stage receives the input as an experience and gives experience as the output.
This means that cellular and molecular mechanisms are receivers and processors of uniformity.
This uniformity or experience is possibly what those mechanisms really do, so that there are no delays in input and output, just get, blend and give, using similar uniformity.
In the brain, the physiology and anatomy of its contents are “maybe” mostly known, but some are also elusive. Thoughts are in the brain, but neuroimaging does not show.
So even within the brain, there are constructs — known for experiences yet expansively inaccessible, regardless of the limited reaches of neurotechnology.
Basically, nutrition and fitness [as experiences] have to become what the brain can take, work and give [parallel experiences].
At work, they have to go to places to compete with whatever is—or could be—responsible for deficient mental health, then when they sometimes win, it becomes how the person feels better.
External and internal stimuli or senses have two major landing areas in the brain, the olfactory bulb for smell, the thalamus for all other senses. It is from there they get distributed across the cortex.
Any sense [or input] has a landing deck, where, it is proposed, they become something that the brain can use. It is this usable quantity that gets relayed for interpretation, which includes knowing, feeling and reaction.
Knowing is the memory, and from the memory, outputs can begin, either in decision-making, imaginations, recall, and so on, such that the output is of the same quantity, which the memory receives and stores, theoretically.
The memory has stores, in the smallest of units, as capsules of the quantity that travels to groups — bearing similarities — within memory locations, before leaving and going to the destination for feeling effects, before reactions: parallel or perpendicular.
If there is any mood disorder, depression, anxiety, whatever else, they mostly affect that quantity and the memory, because it is the quantity that travels and it is in the memory that determinations are made before further transport to other places.
The quantity is postulated to be thought or a form of thought.
Fitness and nutrition shape thoughts and memory for benefits to mental health.