"How to Prevent Alzheimer’s With Diet"
What is behind the dramatic increase in dementia
in Japan over recent decades?
Maybe it’s rising obesity rates
or the increases in cholesterol, saturated fat, and iron,
or increases in animal products and meat.
Overall, calories just went up about 10% in Japan,
whereas animal fat and meat consumption rose 500%,
about 10 times the rise in sugary junk.
Now, during this timespan, rice consumption went down,
but the thinking is that
rather than white rice somehow being protective,
maybe they were just eating something worse instead.
It’s like when you find fish consumption
is correlated with less disease,
you wonder if it’s because they’re eating that
rather than some worse meat.
If you look across multiple countries,
you see a similar pattern,
with the most important dietary link to Alzheimer’s
appearing to be meat consumption,
with eggs and high-fat dairy also maybe contributing.
There appears to be a really tight correlation
between Alzheimer’s and per capita meat supply.
And, then, studies within countries uncover similar findings,
with Alzheimer’s and cognitive decline
associated with meaty, sweety, fatty diets,
whereas most plant foods were associated
with risk reduction.
This could be for a variety of reasons.
Animal products tend to have
more copper, mercury, lead, and cadmium,
and no folate,
but contain saturated fat and cholesterol,
and pro-inflammatory advanced glycation end products;
so many mechanisms that dietary modification
may be our best bet
for reducing risk of Alzheimer’s disease.
But, how do we know it’s cause-and-effect –
the evidence that meat consumption
is causally linked to Alzheimer’s disease?
Well, there’s the strength of the association,
the consistency across different types of studies,
the fact that the dietary changes
preceded the risk of dementia,
the dose response—
more meat linked to more risk—
a bunch of plausible mechanisms.
We know that meat is a risk factor
for other chronic diseases,
but there’s never been randomized controlled trial
to put it to the test.
When you read reviews of the damaging effects
of high-fat diets to the brain and cognition,
a number of factors are proposed
to account for the high-fat diet-induced
damage to the brain.
Oxidative stress, insulin resistance, inflammation,
and changes to blood vessels
and the integrity of the blood brain barrier.
But, these are based mostly on studies of rodents.
Yes, high fat diets can cause
energy dysfunction in the brain,
based on fancy MRI techniques,
but if you’re looking at that and thinking
that’s a weird looking brain,
that’s because those are rat brains.
Let me show you two sets of human cerebral arteries,
the arteries deep inside your skull.
These are the brain arteries on autopsy
of non-demented elderly individuals.
Here are the arteries from Alzheimer’s patients,
clogged nearly completely shut
with atherosclerotic plaque packed with fat and cholesterol.
With CT scans, you can follow this
intracranial artery stenosis,
this brain artery clogging, over time,
and follow the progression from mild cognitive impairment
to Alzheimer’s disease.
Those who only had low-grade stenosis
were pretty stable over time
in terms of their cognitive function
and ability to dress themselves,
and other activities of daily living,
whereas those with more clogging
started slipping over the years.
And those who started out with the most
brain atherosclerosis rapidly went downhill,
and twice as likely to progress
to full-blown Alzheimer’s.
Chronic consumption of standard Western diets,
and rich in saturated fat and cholesterol,
may compromise our cerebrovascular integrity
compromise the blood vessels in our brain.
So, of course, drugs are recommended,
“pharmacological modulation” of diet-induced dysfunction.
But why not just try to eat healthier...
in the first place?