I know you work hard to make the best lifestyle choices
so you can improve your health, destiny, and longevity.
And there’s lots of information out there on how to do just that.
So where do you start? Well – we start with the facts.
Welcome to the Nutrition Facts Podcast – I’m your host Dr. Michael Greger.
My job is to bring you the latest peer- reviewed nutrition and health research
and share it with you here.
Today we’re going to look at the research on the best diet for optimal athletic performance.
Starting with the effects of spinach and berries on oxidative stress,
inflammation, and muscle soreness in athletes.
Higher fruit and vegetable consumption was found
to be positively associated with muscle power in adolescents,
but that’s not who really needs it.
What about the consumption of fruit and vegetables
and risk of frailty in the elderly?
Higher fruit and vegetable consumption
was associated with lower frailty as well,
in a dose-response manner,
meaning more fruit less frailty, and more vegetables too,
but these were all observational studies,
which can’t alone prove cause-and-effect.
What happens when you put foods to the test?
Well, no positive influence ingesting chia seed oil
on human running performance,
but there was an effect found for spinach supplementation
on exercise-induced oxidation stress.
And by spinach supplementation, they meant they just gave some guys
some fresh raw spinach leaves, one gram per kilo,
so like a quarter of a bunch a day for two weeks
and then they had them run a half marathon.
And, they found that “chronic daily
oral supplementation of spinach,”
uh meaning like eating a salad,
has alleviating effects on known markers
of oxidative stress and muscle damage,
Here’s what happens when you run
a half marathon without spinach:
a big spike in oxidative stress, blood malondealdehyde levels,
that stay up hours or even days later.
In the spinach group, the before and after 2 weeks
of spinach doesn’t seem to make much of a difference,
but put the body under pressure,
and then you can really see the difference.
Your body is better able to deal with the stress.
And, if you look at the resulting muscle damage,
as measured by creatine kinase leakage from your muscles
(that's an enzyme that should be in your muscles,
not leaking out into your blood),
you start out at about 100
and go up to 200 after the half marathon,
right after, 2 hours later.
But it’s the next day where you really feel it,
that delayed onset muscle soreness,
with CK levels reaching 600 before coming back down.
Okay, that’s without spinach, though.
On spinach, you get a similar
immediate post-race bump,
but it’s that next day where spinach really shines.
You don’t get that same next-day spike,
and so, for a competitive athlete, that quicker recovery
may get you back training harder sooner.
They attribute this to the anti- inflammatory effects of spinach.
Same with black currant juice.
After some hardcore weight lifting,
muscle damage indicators go up and stay up,
whereas the same lifting drinking berries,
and it goes up, but comes right back down.
But these were just measures of a biomarker of muscle soreness.
What about actual soreness?
If you look at the effects of tart cherry juice
on recovery following prolonged, intermittent
sprints in soccer players,
you see the same kind of reduction
in biomarkers of inflammation,
but more importantly, less resulting muscle soreness.
Then, they measured maximum voluntary isometric contractions of the leg muscles,
which understandably took a hit
in the days after the intense workout,
but not in the cherry group.
They conclude that participants supplemented with a
tart cherry concentrate were able
to maintain greater functional performance.
But, that was testing like how high
can you vertically jump.
They didn’t actually see if they played soccer any better.
But, this study on purple grape juice
actually showed an ergogenic effect
in recreational runners by promoting
increased time to exhaustion,
where you ramp people up on a treadmill
and see how long they can go before collapsing.
After a month of drinking a grape Kool-Aid
type placebo control drink,
no real change in performance,
but a whopping 15% improvement in the real grape group–
hung on for another 12 minutes.
They used juice, so they could make
a matched placebo control drink,
but you can buy concord grapes fresh, or tart cherries fresh, frozen,
or water-packed in a can.
I mix them with oatmeal, cocoa, and mint leaves
for a chocolate-covered- cherry type sensation.
You may want to try that for a few days
before participating in your next big sporting event.
Next up – we look at the pros and cons of fennel fruits
as a cheap, easy-to-find, nonperishable source of nitrates.
Dozens of studies now suggest that the nitrates in vegetables,
such as beets and green leafy vegetables, may help
both sick people as a low-cost prevention and treatment intervention
for patients suffering from blood flow disorders such as high blood pressure
and peripheral vascular disease, as well as healthy people as an effective,
natural performance-enhancing aid for athletes.
Most of the studies were done on beet juice,
which is why I was so delighted to see the study on whole beets
as I reported before, showing the same benefit.
But what about studies on whole green leafy vegetables?
There was this study awhile ago suggesting that one of the reasons
that at the age many Americans and Europeans are dying,
the Okinawan Japanese are looking forward to many more years
of good health -- at least they were --
is all the nitrate in their green leafy vegetables, which tended to bring down
blood pressures when put to the test.
The reason I didn't report on it at the time is because I never heard
of these vegetables. I know what chrysanthemum flowers are, but I didn't
think most of my viewers would be able to find these at the local store.
What about good old American, red, white, and blue greens,
like frozen spinach. It hadn't been tested -- until now.
They wanted to test the immediate effects on our arteries
of a single meal containing a cooked box of frozen spinach
for both arterial stiffness and blood pressure.
First they needed a meal to increase artery stiffness and pressure,
so they gave people a chicken and cheese sandwich,
which lowered the elasticity of their arteries within hours of eating,
but add the spinach and the opposite happens.
After chicken and cheese, the force the heart has to pump
goes up within minutes, but the spinach keeps things level.
So, a meal with lots of spinach can lower blood pressure
and improve measures of arterial stiffness.
That's great for day-to-day cardiovascular health,
but if you want a whole food source that can improve your performance
when you're out hiking or something?
Beets and spinach aren't the most convenient of foods.
Is there anything we can just add to our trail mix?
Well, if you look at the list of high nitrate vegetables,
you'll see there isn't much you can just stick in your pocket --
unless fennel seeds have a lot, which are actually not seeds at all,
but the whole little fruits of the fennel plant. Let's find out.
Fennel seeds are often used as mouth fresheners after a meal
in both the Indian sub-continent and around the world.
You'll typically see a bowl of candy coated fennel seeds
as you walk out of Indian restaurants.
And when you chew fennel seeds you can get a significant bump
in nitric oxide production, which has the predictable vasodilatory effect
of opening up blood vessels, making them a cheap, easy way
to carry a light-weight, nonperishable source of nitrates.
They single out mountaineers, thinking chewing fennel seeds
could help maintain oxygen levels at high altitudes
and help prevent H.A.P.E. (high altitude pulmonary edema),
one of the leading killers of mountain climbers
once you get more than like a mile and a half above sea level.
Not to be confused with H.A.F.E caused by the expansion of gas at high altitudes,
a condition known as High Altitude Flatus Expulsion,
known to veteran back-packers as Rocky Mountain barking spiders.
But fennel seeds may help with that too,
as traditionally they've been used as a carminative,
meaning a remedy for intestinal gas.
Fennel has also shown anti-hirsutism activity, combatting excessive
hair growth in women, the so-called bearded woman syndrome,
but applying a little fennel seed cream can significantly reduce it.
But if fennel seeds have such a strong hormonal effect,
should we be worried about chewing them?
Well, there have been cases reported of premature breast development among
young girls drinking fennel seed tea a couple times a day for several months.
Their estrogen levels were elevated, but after stopping the tea
their chests and hormone levels went back to normal.
Current guidelines recommend against prolonged use in vulnerable groups,
children under 12, pregnant and breastfeeding women,
and perhaps your pet rat, as rodents metabolize a compound in fennel
called estragole into a carcinogen, but but our cells appear able to detoxify it.
Finally today, what is the latest science on the performance-enhancing qualities
of nitrate-rich vegetables? Let’s find out.
Nitrates, concentrated in green leafy vegetables and beets,
underwent a great makeover a few years ago
from inert substances to having profound effects
on the power plants within all of our cells,
reducing the oxygen cost during exercise
meaning we can bust out the same amount of work with less oxygen.
So one little shot of beet juice allows free divers to hold
their breath for over four minutes. They get about a half minute longer.
And for others this improved muscle efficiency
allows athletes to exercise at a higher power output
or running speed for the same amount of breath.
But that was back in 2012.
What's happened since?
Well, this all led to many athletes, elite and amateur alike,
consuming beetroot juice prior to competition.
But what does the new science say?
Well, most of the studies were done on men.
Turns out it works on women, too, even African-American women –
an even more neglected research demographic.
Same workload power outputs using significantly less oxygen
after drinking beet juice. But forget beet juice.
What about whole beets?
Cheaper, healthier, can find them in any produce aisle,
but there had never been any studies on actual beets, until now.
Whole beetroot consumption acutely improves running performance.
They gave physically fit men and women
a cup and a half of baked beets, which is equivalent to about a can of beets,
75 minutes before running a 5k.
They started out the same, but during the last mile of the 5k race
the beet group pulled ahead compared to the placebo group,
who were given berries instead.
Though they were running faster, their heart rate wasn't any higher.
If anything, the beet group reported less exertion.
Faster time with less effort?
They don't call them block-rocking beets for nothing.
But if nitrates are so good why not just take them in a pill,
nitrate supplements with names like "Hellfire."
Although they can work, their long-term safety is questionable.
Non-vegetable sources of nitrates may have detrimental health effects.
So if we want to improve our performance,
we should really ideally obtain nitrates from whole vegetables.
The industry knows this, so instead markets an array
of nitric oxide stimulating supplements.
However, there is little or no evidence
of a performance improvement following supplementation
with these so called NO boosters.
The evidence is with the vegetables.
How much money can companies make selling beets though?
So how about a novel beetroot-enriched bread product?
We've tried to get people to eat their fruits and veggies
and where has that gotten us?
But hey, lots of people eat white bread.
So why not have them eat red bread?
And indeed it worked.
Red beet bread brought down blood pressures,
improved the ability of arteries to relax and dilate naturally.
Bread, therefore, may be an effective vehicle
to increase vegetable consumption without significant dietary changes,
because, heavens forbid, people should have
to change their diet to improve their health.
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please go to the Nutrition Facts Podcast landing page.
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