“Anti-inflammatory Diet for Depression”
Depression affects more than 150 million people worldwide,
making it a leading cause of losing healthy years of life
as a result of disability.
In fact by 2020, depression may be the second leading cause
of healthy years of life lost, second only to heart disease.
Why is depression so common?
Well, it is said “Nothing in biology makes sense except
in the light of evolution,”
but why would be evolve to get depressed?
Depression poses a baffling evolutionary puzzle.
It has such negative effects, but remains so common and heritable,
meaning a big chunk of risk is passed down through our genes,
so there must be some kind of adaptive benefit.
Otherwise, presumably, it would have been naturally selected against.
Maybe, depression is an evolutionary strategy for defense against infection.
Infection has been the leading cause of mortality
throughout human history.
The average life expectancy was 25,
and it was not uncommon for half our kids to die.
With such stark capabilities, infection has been a critical
and potent driving force in natural selection.
When we become infected, there is a surge of inflammation
as our body mounts a counterattack, and then what happens?
We feel lousy. We feel sick, we get weak, tired, slow, and sleepy.
We don’t see anyone; we don’t want to do anything;
all we want to do is sleep.
It’s like we’re depressed—
and that’s great for fighting infection.
Not only does that help us conserve energy so we can
put up a good fight, but reduces social contact,
we’re not running around infecting everyone.
It’s the same reason we evolved to think poop doesn’t smell good,
or decaying flesh.
That keeps us safe from infection.
In fact, we see this phenomenon with other social animals
like honeybees and mole rats
who feel impelled to crawl off and die alone when they get sick,
which reduces the risk to the rest of the community.
The relationship between mental health and inflammation
was first noted in 1887, for which the only psychiatrist
to ever win the award got a Nobel Prize.
But what evidence have we accumulated in the century since
that inflammation causes depression?
Well, people who are depressed have raised inflammatory markers
such as C-reactive protein.
Inflammatory illnesses are associated with greater rates of major depression.
Indeed, that’s what’s found in a variety of inflammatory conditions
including more benign inflammatory conditions,
like as asthma and allergies,
and that’s important, suggesting the mood symptoms
are not simply ‘feeling bad about having a terrible disease’
but may be directly tied to the inflammation.
Most powerfully, you can actually induce depression
by inducing inflammation, like when we give interferon
for certain cancers or chronic infections—
up to 50% go on to suffer major depression.
Even just giving a vaccine can cause enough inflammation
to trigger depressive symptoms.
Taken together, these studies are strongly suggestive of
inflammation being a causative factor of mood symptoms.
So can an anti-inflammatory diet help prevent depression?
We didn’t know…
until about 43,000 women without depression were followed,
along with their diets, for about a dozen years
to see who became depressed, and it was those who at a more
inflammatory dietary pattern,
characterized by more soda, refined grains and meat,
suggesting that chronic inflammation may underlie the association
between diet and depression.
Normally, we think of omega-3’s as anti-inflammatory,
but they found fish to be pro-inflammatory,
associated with increased C-reactive protein levels consistent with recent findings
that omega-3’s don’t seem to help with either depression or inflammation.
The most anti-inflammatory diet is plant-based,
which can cut C-Reactive Protein levels by 30% within two weeks.
Perhaps because of the anti- inflammatory properties of antioxidants.
I’ve talked about this before, but never explained WHY
antioxidants are anti-inflammatory.
Oxidative damage caused by free radicals may cause
an autoimmune response in the body by changing the chemical structures
of otherwise ubiquitous molecules to generate new structures
that the body attacks as foreign.
For example, when LDL cholesterol gets oxidized,
our body creates antibodies against it and attacks it.
And so clinical depression can be accompanied by increased oxidative stress
and the autoimmune inflammatory responses it creates.
Free radicals lead to auto-immune inflammation.
Where else does inflammation come from in our diet?
Endotoxins. It’s worth reviewing how the endotoxins in animal products
can cause a burst of inflammation within hours of consumption.
What does it do to our mood?
If you inject endotoxin into people, within a few hours, inflammation shoots up,
and so does feelings of depression,
as well as feelings of social disconnection from people.
Although previous research has demonstrated that inflammatory activity
contributes to depressive symptoms,
no work in humans has examined the effect of experimentally induced
inflammation on anhedonia—
a key diagnostic feature of depression,
as well as anhedonia, the lack of reaction to pleasurable stimuli—
this is an an important symptom of depression.
No work has been done that is....
until now.
Within hours of endotoxin hitting their bloodstream,
these experimental subjects not only started to feel depressed,
but they had significant reductions in activity
in the reward center of the brain.
They were less excited about winning money
playing video games, for example in the study.
But by eliminating animal products, and eating antioxidant rich diets,
we may be able to prevent or treat depression.