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.
It’s time for the Nutrition Facts Grab Bag,
where we look at the latest science on a whole variety of topics.
In our first story, we’ll look at the dangerous effects of heavy metal music.
If you search for heavy metal in the National Library of Medicine database,
most of what you find is on heavy metal contamination in fish, for example,
making it so hard to clearly establish the role of fish in a healthy diet,
perhaps helping to explain the quintupling of odds
of autoimmune diseases like juvenile arthritis for instance.
But searching the hazards of heavy metal also pops up entries
like this, on the “risks from heavy metal music.”
Here they were talking about traumatic injuries from slamming around,
but you’re more likely to get injured at an alternative rock concert.
It’s the Goo Goo Dolls you’ve got to worry about, not Nine Inch Nails.
Okay sure, music-induced hearing loss is a serious problem,
but that can be from any loud music.
It’s interesting, clinical recommendations
include the “80–90 rule”: no more than 80%
of the maximum volume on personal listening devices
for no more than 90 minutes a day. But that’s not what the science shows;
“do not exceed 60 percent of the maximum volume”
may be more evidence-based, but they figure
teens would just ignore that,
so they came up with more “acceptable” advice.
I assumed I’d see a lot of satanic panic nonsense from the 80’s,
where parents bereaved by suicide started suing heavy metal musicians.
What kind of evidence did the parents present?
There has been little scholarly research until... this study that proceeded
to try to correlate the number of statewide heavy metal magazine
subscriptions to youth suicide rates.
Oh, you’ve got to be kidding.
It got really crazy, though, when researchers
called psychiatric institutions pretending to be parents
worried because their son started listening to that heavy metal music,
even though they made it clear that their son didn’t exhibit
any symptoms of mental illness,
no drugs, no alcohol, and was doing fine at school.
Ten of the twelve facilities believed
the son required psychiatric hospitalization.
Imagine what that would do to a kid!
In turns out if you actually come back a few decades later,
metalheads were signiﬁcantly happier in their youth and appear
better psychologically adjusted than their peers.
Some studies were just strange. Do Parkinson’s patients walk better
listening to “Yellow Submarine” or “Master of Puppets”?
Other studies were just like, duh.
Heavy metal musicians exhibit a higher heart rate than those
performing “contemporary Christian.” Not much of a shocker.
Some studies were kind of cute: the Influence of music on promoting
patient safety during surgery—veterinary patients.
Kitties getting spayed with little earphones on their head.
It turns out that “Adagio for Strings” may be more relaxing than AC/DC.
A review on music therapy for human patients warned that
caution should be exercised when guiding patients in selecting
their music, as “chaotic music,” such us hip-hop and metal,
is not healing to human cells— with three citations no less,
though two of them don’t say anything, and the third
is a nursing newsletter merely quoting someone’s opinion.
But I did some digging, and it turns out stomach cancer cells like metal.
If you play them "Cannibal Corpse" versus Beethoven, 12 hours of
death metal increased their growth in a petri dish (that’s so metal).
But who puts headphones on their stomach?
Or their chests, for that matter?
While in one study, Mozart killed off one type
of breast cancer cell line and not another;
in another study, only Beethoven’s 5th Symphony seemed to work,
and Mozart flopped when the petri dishes were surrounded
by speakers on a little platform.
How do they even get this stuff published?
Anyway, the true danger from heavy metal is headbanging.
"Headbanging is a contemporary dance form consisting of abrupt
ﬂexion–extension movements of the head,"
commonly seen in heavy metal.
The number of avid aﬁcionados is unknown, but some fans
might be endangered by indulging excessively.
Although generally considered harmless, health complications
attributed to this practice include ripping your carotid artery,
rupturing your lung, whiplash injury, and neck fracture,
or in this case a subdural haematoma.
This guy reported headbanging at a Motörhead concert,
and all that brisk forward and backward acceleration might have
ruptured his bridging veins and caused him to bleed into his skull.
Bridging veins bridge the gap between the brain and the covering
that lines the inside of your skull, and if the veins tear,
blood can build up under your skull and compress your brain.
This bridging vein rupture has been demonstrated on headbanging cadavers
(again, a very metal study).
It’s been likened to a kind of shaken-baby syndrome in adults.
The researchers conclude that their case serves as evidence
in support of Motörhead’s rock-and-roll reputation,
but I think the real takeaway is that a potentially dangerous complication
like that can result from a seemingly benign activity.
And some of the brain bleeds can be massive.
See, you can tear more than just veins.
There are two sets of arteries that tunnel into the skull—
the carotid arteries in the front and the vertebral arteries in the back—
and you can tear both sets.
A 15-year-old indulged in headbanging, ripping his carotid artery,
which led to a massive stroke; and he presented half paralyzed,
and unable to speak, and died in a coma within a week.
What about the vertebral arteries in the back?
They’re wedged into your skull rendering them susceptible to
shearing forces from extremes of neck motion,
and that’s exactly what appeared to happen:
a heavy metal drummer tearing the wall of the artery.
Now obviously, all this is really rare, probably afflicting
less than one in a thousand or so.
What can metalheads do to reduce their risk?
To prevent injury due to such head-banging, the range of head
and neck motion should be reduced;
slower-tempo music should replace metal
(good luck with that); the frequency of head-banging could be only
on every second beat (that’s actually not a bad idea);
or personal protective equipment should be used
(what like a neck brace?).
Little formal injury research has been conducted on the world-wide
phenomenon of head banging; so, researchers constructed
a theoretical head banging model with enough physics terms
to make any nerd happy: angular displacement, sinusoidal motion
in the sagittal plane, amplitude of the displacement curve.
Study participants: head bangers.
But you do need a control group: easy listening music.
Head injury curves; neck injury curves,
based on headbanging tempo and angular sweep.
At an average head banging tempo, we’re trying to keep
the range of motion under 75 degrees, so something like this.
So, to minimize the risk of head and neck injury, head bangers
should decrease their range of head and neck motion.
Oh, there’s that “personal protective equipment” again.
“Unfortunately, it is difﬁcult, if not impossible,
to change the habits of heavy metal aﬁcionados.”
Maybe what we need are metal-studded neck braces.
In our next story, we look at what the gut has to do
with developing Parkinson’s disease.
Parkinson's disease is an ever-worsening neurodegenerative disorder that results
in death and affects about 1 in 50 of us when we get older.
A small minority of cases are genetic and run in families,
but 85 to 90% of cases are sporadic, meaning they just seemingly pop up
out of nowhere.
It's caused by the death of a certain kind of nerve cell in the brain.
Once about 70% of them are gone, the symptoms start.
Okay, so what kills off those cells? It's still not completely clear,
but the abnormal clumping of a protein called alpha-synuclein (α-synuclein)
is thought to be involved. Why? Because if you inject blended
Parkinson's brains into the heads of rats or monkeys, you can induce
Parkinson's pathology and symptoms,
or even just injecting the pure clumped α-synuclein strands themselves.
Okay, but how do these clumps naturally end up in the brain?
It all seems to start in the gut.
The part of the brain where the pathology often first shows up is directly connected
to the gut, and we have direct evidence of the spread
of Parkinson's pathology from the gastrointestinal tract to the brain.
Alpha-synuclein from brains of Parkinson's patients
is taken up in the gut wall,
and creeping up the vagal nerves from the gut into the brain.
But this was in rats. If only we had a way to go back
and look at people's colons before they got Parkinson's.
And indeed, we can. Old colon biopsies were dredged up
from people who had later developed Parkinson's,
and years before symptoms arose, you could see the α-synuclein in their gut.
Research supported by the Michael J. Fox Foundation has found
you can reliably distinguish the colons of patients from controls
by the presence of the Parkinson's protein lodged in the gut wall.
But how did it get there in the first place?
Perhaps vertebrate food products
as a potential source of prion-like α-synuclein.
See, nearly all of the animals with back bones that we eat--
cows, chickens, pigs, and fish-- express the protein α-synuclein.
And so when we eat common meat products, when we eat
skeletal muscle, we're eating nerves, blood cells,
and the muscle cells themselves.
Every pound of meat has like a teaspoon to a tablespoon of blood in it,
and that alone could be an α-synuclein source
to potentially trigger a clumping cascade
of our own α-synuclein in the gut. Though it may seem intuitive
that dietary α-synuclein could seed this kind of buildup in our gut,
what evidence do we have that it's actually happening?
These are pretty interesting data.
There's a surgical procedure called a vagotomy
in which the big nerve that goes from your gut to your brain is cut
as an old-timey treatment for stomach ulcers.
Would cutting communication between the gut and the brain reduce Parkinson's risk?
Apparently so, suggesting that the gut to brain vagal nerve
may be critically involved in the development of Parkinson's disease.
Now, of course, many people regularly consume meat and dairy products,
but only a small fraction of the general population will develop Parkinson's.
So there must be other factors at play that may somehow provide
an opportunity for unwanted dietary α-synuclein
to enter the host and initiate disease.
For example, your gut becomes leakier as you age so might that play a role?
Well, what else makes your gut leaky?
Dietary fiber deprivation has also been shown to degrade the intestinal barrier
and enhance pathogen entry.
So this all raises possibilities for food-based therapy.
Parkinson's patients have significantly less Prevotella in their gut, a friendly
fiber-eating flora that bolsters your intestinal barrier function.
So low levels of Prevotella are linked to a leaky gut,
which has been linked to intestinal α-synuclein deposition.
But fiber-rich foods may bring Prevotella levels back up.
Therefore, by adopting a plant-based diet,
in addition to getting the beneficial effects of phytonutrients,
it's possible that increasing overall fiber intake may modify
the gut microbiome and gut leakiness in beneficial ways.
So, does a vegan diet, one with lots of fiber and no meat,
reduce risk for Parkinson's disease?
Parkinson's does appear to be rare in quasi-vegan cultures.
Rates are about five times lower in rural sub-Saharan Africa for instance.
Now all this time we were thinking the benefits seen for Parkinson's
from plant-based diets was due to the antioxidants
and anti-inflammatory nature of the animal-free diets,
but maybe it's also due to the increased intestinal exposure to fiber and
decreased intestinal exposure to ingested nerves, muscles, and blood.
Finally today, we look at what randomized controlled human trials
tell us about the ways we may—
or may not—benefit from eating onions.
Onions are potentially a good source of antioxidants,
though interestingly, the antioxidants are concentrated
in the outer layers immediately under the papery peel.
Unfortunately, most consumers discard these most nutrient-rich
outermost layers, thus losing a valuable part.
Here are some numbers. Look at that!
More than 10 times more antioxidants in the
outer layer of white onions, compared to the core.
You’ll also note that yellow onions in general
have more antioxidants than white.
And red onions beat them both, based on three
different antioxidant testing methods.
That’s why I always try to buy red.
Though red onions are indeed slightly better, yellow
or white onions are no slouches, containing
considerable levels of antioxidant activity.
So, nutritious, sure, but are there any particular
clinical benefits to onion consumption?
For example, here’s a review purporting to have evidence
that testosterone in males are enhanced by onion,
but the researchers were talking about studies like this on
the effects of onion juice on testicular torsion . . . in rats.
Who cares what happens after a rat testicle is rotated
720 degrees counterclockwise? (Except, of course, the rat.)
You don’t know what happens in people until you put
human testes to the test and . . .
onion extracts don’t appear to work.
Okay, what about bone health?
Evidently, older white women who consumed onions at least
once a day had an overall bone density that was 5% greater than
individuals who consumed onions no more than once a month (P < 0.03).
Now 5% might not sound like a lot, but that improvement in
bone density could potentially translate into decreasing
their risk of hip fracture by more than 20%
if indeed, it was cause and effect.
Daily administration of onion did cause a big bump in bone density.
This opens the possibility for a low-cost, safe, and effective
nutritional approach to osteoporosis and—
you guessed it...in the rat. Another rodent study.
Rats!
But finally, here we go.
Tremendous strides have been made
in treating osteoporosis with drugs, but they have the potential
for serious adverse side effects, so scientists have drawn
their attention to natural remedies.
So, let’s randomize people to drink... onion juice
or placebo onion juice.
I don’t know what sounds worse: sugary onion juice
or fake sugary onion juice.
And as if drinking onion juice wasn’t bad enough,
it was all for nothing. It didn’t even work.
What about the antiallergy activities of shallots
and any therapeutic effects on helping allergic runny noses?
Sixteen such patients were randomized equally into
an antihistamine group or a group that got antihistamines
plus some capsules containing dried shallot powder.
And it looked like the shallot group did better,
but there was actually no statistically significant difference
in total symptoms between the two groups;
so, another #OnionFail.
There has to be something onions can do.
What about testing the effects of fresh yellow onion consumption
on breast cancer patients to try to decrease the toxic effects
of a chemotherapy drug called doxorubicin?
Unfortunately, no significant benefit was found on decreasing
damage to the liver or heart.
But here we go . . . finally, a clinical benefit to onions.
The consumption of fresh yellow onion ameliorates
the high blood sugars and insulin resistance in breast cancer
patients during doxorubicin- based chemotherapy.
Doxorubicin isn’t just toxic to the liver and heart,
but it may also contribute to insulin resistance.
So, let’s do a randomized, triple-blind, controlled clinical trial
randomizing patients to like a whole onion a day
or a third of an onion a day. What happened?
The high onion group experienced a significant decrease
in blood sugars and insulin resistance
compared to the low onion group.
They went up in the low onion group but down in the high onion group.
So, make onions your friend.
What’s the worst that can happen— a little onion breath and BO?
Probably the least of your worries if you have cancer on chemotherapy.
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please go to the Nutrition Facts Podcast landing page.
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