Let's say you're trying to lose 20 pounds, or boost your immunity,
or increase your ability to fight COVID, or even cancer.
Well, the amazing thing is, with the right diet,
you're well on your way to achieving these vital health goals.
Welcome to the Nutrition Facts Podcast. I'm your host, Dr. Michael Greger.
Today, we can finally justify eating nuts with wild abandon.
And we’ll start with a little known nut called baru nuts.
There is a new nut on the market called baru almonds
branded as “barukas,” or just baru nuts.
Technically, it isn’t a nut but a seed that's native to the Brazilian Savannah,
known as the Cerrado, which is sadly now among the most
threatened ecosystems in the world.
Over the last 30 years, extensive cattle ranching and feed crop production
to fatten said cattle have destroyed much of this ecosystem.
So, hey, if we can make it profitable not to cut down the native trees
by selling baru nuts, for example, then that could be good
for the ecosystem’s health. But what about our health?
Although baru nuts are popular and widely consumed,
few studies report on their biological properties.
They do have a lot of polyphenol phytonutrients,
presumably accounting for their high antioxidant activity,
and 90%of the phytonutrients are present in the peel.
So, are they nutritious? Sure.
But do they have any special health benefits
(and not just for the treatment of chubby mice)?
Groups fed baru nuts showed lower cholesterol, supposedly indicating
that they have a great potential for dietary use in
preventing and controlling cholesterol problems.
But their groups were rats, and that was compared to lard.
Basically anything lowers your cholesterol compared to eating lard.
Nevertheless, there haven’t been any reports about the effect
of baru almonds consumption on human health, until this study.
A randomized, controlled study of humans found that eating less
than an ounce a day for six weeks led to a 9% drop in LDL cholesterol.
Twenty grams would be about 15 nuts or a palmful.
Like many other nut studies, even though the research subjects
were told to add nuts to their regular diets, there was no weight gain,
presumably because nuts are so filling, you inadvertently
cut down on other foods throughout the day.
How good is a 9.4% drop in LDL?
Well, that’s the kind of drop you can get from regular almonds,
though macadamias and pistachios may work even better,
but those were at much higher doses.
So, it appeared that 20 grams of baru nuts worked as well as
73 grams of almonds, and so on a per serving basis,
or a per calorie basis, baru nuts really did seem to be special.
Now there are lower dose nut studies showing
similar or even better results.
Here people were given 25 grams of almonds for just four weeks
and got about a 6% drop.
And in this study, people were given just 10 grams of almonds a day,
I mean we’re talkin’ just seven individual almonds a day,
and got more like a 30% drop in the same time frame as the baru nuts.
Three times better at half the dose with regular almonds.
The biggest reason we’re more confident in regular almonds
is that studies have been done over and over,
more than a dozen randomized controlled trials,
whereas in the only other cholesterol trial of baru nuts
there was no significant benefit at all for LDL cholesterol,
even at the same 20-gram dose given for even longer—
a period of eight weeks. That’s a bummer.
The primary reason I would suggest choosing other nuts instead,
though, is that you can’t get baru nuts raw.
They contain certain compounds that have to be inactivated by heat
before human consumption.
So, the reason raw nuts are preferable is because of advanced
glycation end products (AGEs), so-called glycotoxins,
which are known to contribute to increased
oxidative stress and inflammation.
Glycotoxins are naturally present in uncooked animal-derived foods,
but then dry-heat cooking like grilling can make things worse.
The three highest levels recorded are bacon, broiled hot dogs,
and roasted barbequed chicken skin (nothing comes close to that.)
Chicken McNuggets come in here, but, anyway, any foods high in fat
and protein can create AGEs at high enough temperatures.
So, although plant foods tend to contain relatively few AGEs,
even after cooking, there are some high-fat, high-protein plant foods.
Now again, with most plant foods it’s not at all a problem.
I was surprised that veggie burgers were so low,
even when baked or fried.
But nuts and seeds are up in tofu territory, especially when roasted,
which is why I would recommend raw nuts and seeds
and nut and seed butters whenever you have a choice.
In our next story, we’ll look at some randomized controlled studies
that put nuts, berries, and grape juice to the test for cognitive function.
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.
Finally today, we’ll discover how just a few small servings of nuts a week
may increase our lifespan and lower cancer risk.
We’ve known increased nut consumption
has been associated with a reduced risk of major chronic diseases,
including heart disease and diabetes.
But do those who eat nuts actually live longer lives?
Clinical trials have shown nuts help lower cholesterol and oxidation,
and improve our arterial function, and blood sugar levels,
but does all this translate into greater longevity?
Researchers at Harvard examined the association
between nut consumption and subsequent mortality
of over a 100,000 people followed for decades.
In that time tens of thousands died,
but those that ate nuts every day lived significantly longer.
Daily nut consumers had fewer cancer deaths, heart disease deaths,
and fewer deaths from respiratory disease.
And this was after controlling for other lifestyle factors
so nut consumers lived significantly longer
whether they were older, younger, fat, or skinny,
whether they exercised more, or smoked, drank,
or ate other foods that may affect mortality.
But nuts are so filled with fat that there may be a concern
that frequent nut consumption can result in weight gain.
However, that’s not what they found,
and in fact other studies have associated nut consumption
with a slimmer waist, less weight gain, and lower risk of obesity.
If you look at all the studies put together, it’s pretty much a wash.
Diets enriched with nuts do not seem to affect body weight,
body mass index, or waist circumference much at all.
Hence, it appears, the incorporation of nuts, about 1 or 2 small handfuls a day,
would be advisable to ensure various health benefits
without the risk of body weight gain.
And what was nice about this review is that
there were no apparent ties to the nut industry.
How "nuts" do we have to go?
Not much. Just a few servings a week
may boost our lifespan and lower cancer rates,
but, it appears, we have to keep it up.
In the PREDIMED study, where long-time nut eaters
were told to cut down on eating nuts or choose extra virgin olive oil,
within 5 years they apparently lost much of their longevity benefit.
Only the group that started out eating nuts
and continued to eat at least the same amount of nuts
had the significant survival advantage.
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please go to the Nutrition Facts Podcast landing page.
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