"Fighting the Blues With Greens?"
Why does frequent consumption of vegetables
appear to cut ones odds of depression by more than half?
And by more frequent they mean eating vegetables
not 3 or more times a day,
but just 3 or more times a week.
But even that seemed to cut the odds of developing depression
by 60% after controlling for a long list of variables.
In the 2012 study that found that eliminating animal products
improved mood within 2 weeks,
the researchers blamed arachidonic acid,
primarily in chicken and eggs,
which may adversely impact mental health
via a cascade of brain inflammation.
But better moods on plant-based diets
could also be from the good stuff in plants,
a class of phytonutrients
that crosses the blood brain barrier into our heads.
This recent review in the journal Nutritional Neuroscience,
suggests that eating lots of fruits and vegetables
"may present a noninvasive natural and inexpensive"
"therapeutic means to support a healthy brain."
Yeah, but how?
Well, to understand the latest,
we need to understand the underlying biology,
the so-called monoamine theory of depression -
the thought that depression may arise
out of a chemical imbalance in the brain.
Here's the oversimplified version:
One of the ways that billions of nerves in our brain
communicate with one another is through chemical signals
called neurotransmitters.
Here's the end of one nerve and the beginning of another.
This is what it actually looks like under a microscope.
Note the two nerve cells don't actually touch—
there's a physical gap between them.
To bridge that gap, when one nerve wants
to tap the other on the shoulder
it releases chemicals into that gap,
including three monoamines:
serotonin, dopamine, and norepinephrine.
These neurotransmitters then float over
to the other nerve to get its attention.
The first nerve then sucks them back up
to be reused the next time it wants to talk,
but it's also constantly manufacturing more,
and an enzyme, monoamine oxidase,
is constantly chewing them up
to maintain just the right amount.
The way cocaine appears to work
is by acting as a monoamine re-uptake inhibitor.
It blocks the first nerve from sucking back up
those three chemicals and so
there's this constant tapping on the shoulder,
this constant signaling to the next nerve.
Amphetamines work in the same way,
but also increase monoamine release.
Ecstacy works like speed,
but just causes comparatively more serotonin release.
After awhile, the next nerve
may be like "enough already!"
and down-regulate its receptors
to turn down the volume.
It puts in ear plugs. So you need more and more
of the drug to get the same effect.
Then when you are not on the drug
you may feel crappy because normal volume transmission
just isn't getting through as much.
Antidepressants are thought to work along similar mechanisms.
People who are depressed appear to have
elevated levels of monoamine oxidase in their brain.
That's the enzyme that breaks down those neurotransmitters,
and so if you have too much of that enzyme
in critical parts of your brain
(the black circles are the levels in the brains of depressed individuals,
and white circles are that of the healthy individuals),
if the levels of your neurotransmitter- eating enzyme is elevated,
then your levels of neurotransmitters drops,
and you become depressed, or so the theory goes.
So a number of different classes of drugs have been developed.
The tricyclic antidepressants,
named because they have three rings like a tricycle,
appear to block norepinephrine and dopamine re-uptake,
and so even though your enzymes
may be eating these up at an accelerated rate,
what gets released sticks around longer.
Then there came the SSRIs like Prozac,
the selective serotonin re-uptake inhibitors.
Now you can know what that means—
they just blocks the re-uptake of serotonin.
Then there are drugs that just block
the re-uptake of norepinephrine,
or more dopamine or the opposite.
But if the problem is too much high levels of monoamine oxidase,
why not just block the enzyme?
Make a monoamine oxidase inhibitor—
and of course they did,
but they're considered drugs of last resort
because of serious side effects,
not the least of which is the dreaded "cheese effect,"
where eating certain foods like certain cheeses
while on the drug can have potentially fatal consequences.
If only there was a way to tamp down the activity
of this enzyme without the whole
bleed-into-your-brain-thing and die-thing.
Now we can finally talk about the latest theory
as to why fruits and vegetables may improve our mood.
There are inhibitors of that depression- associated enzyme in various plants.
There are phytonutrients in spices,
such as cloves, oregano, cinnamon, nutmeg,
but people don't eat enough spices
to get enough into the brain.
This dark green leafy has a lot,
but its name is tobacco,
which may actually be one of the reasons
cigarettes make smokers feel so good.
OK, but what if you don't want brain bleeds or lung cancer?
Well, there is a phytonutrient found in apples, berries, and grapes,
and kale, onions, and green tea
that may indeed affect our brain biology enough to improve our mood.