"Best Brain Foods: Berries and Nuts Put to the Test"
When you read articles like this in Alzheimer’s disease journals,
about how eating more berries may reduce cognitive decline
in the elderly, they’re talking about observational studies like this,
where berry intake appeared to delay cognitive aging by
up to two and a half years in the Harvard Nurses’ Health Study,
or the intake of nuts appearing to delay brain aging by two years.
They’re just talking about associations, meaning
berry eaters and nut eaters tend to have better brain function
as they age after trying to control for a bunch of other
lifestyle factors, but you don’t know if it’s cause and effect...
until you put it to the test.
Thankfully, we now have a growing number of interventional studies
that have done just that.
Randomized controlled trials
where people eat berries or nuts and you can prove it—
actually show improvements in cognitive performance,
raising the berry nutty idea that we may be able to forestall
or reverse the effects of neurodegeneration in aging with food.
For example, this study on the effects of walnut consumption
on cognitive performance.
College students split up into groups
doing two months of walnuts followed by two months of placebo
or vice versa and then they switch.
How do you make a placebo nut?
They baked it in.
They gave people banana bread
with or without nuts; same ingredients,
just one with walnuts, and those on the nuts showed a
significant improvement in “inference capacity,”
the ability to accurately draw conclusions from a set of facts,
in other words, critical thinking.
And so, on a practical level, maybe students or young professionals
in fields that involve a great deal of critical thinking or decision-making
could possibly benefit and gain a slight advantage
through regular consumption of walnuts.
Or this berry study, where they randomized folks
to some crazy berry smoothie with blueberries, black currants, elderberries,
lingonberries, strawberries, and… a tomato.
And not only did their bad cholesterol drop about 10 points,
they performed better on short-term memory tests;
so, good for the heart, good for the brain.
And not just better on like pencil-and-paper tests,
but real-world applications.
Give people concord grape juice versus some fake grape
Kool-Aid-type placebo, and you get improved performance
on everyday tasks—like quicker response times in driving tests.
Why not just give people concord grapes instead of juice?
Well, then, it’s harder to create a placebo
and, of course, the study was paid for by Welch’s.
OK, fruit and nuts, what about vegetables?
Consumers of cruciferous vegetables, like cabbage, cauliflower, kale,
collards, broccoli and Brussels sprouts,
have been found to perform better
in several cognitive tests than non-users.
In terms of cognitive decline with aging,
women consuming the most green leafies did better,
effectively slowing brain aging a year or two,
and not just cruciferous, but other dark green leafies like spinach;
so, maybe it’s the nitrates.
As we age, our cerebral blood flow drops,
the amount of blood flowing through our brain,
which may be due to an age-related decrease
in the production of nitric oxide, the open sesame molecule that
dilates our blood vessels
and is boosted by the consumption of nitrate-rich vegetables.
This reduction in blood flow to the brain
may be a major risk factor for the impairment
of cognitive function and development
of neurodegenerative diseases, such as dementia.
We know nitrate-rich vegetables like leafy greens and beets
can improve physiological performance, like beet juice does for athletes,
but what about cognitive performance?
We’ll find out…next.