ExeTalks: Prof Jo Bowtell, Sport and Health Sciences

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hi there my name's joe botel and i'm a

professor in sport and health sciences

at the university of exeter where i

teach on a range of different

undergraduate and postgraduate programs

in exercise and sports science and in

nutrition

in my research i'm particularly

interested in how we use nutrition and

exercise to support the population to

age more healthily so how we can live

longer and healthier lives and in

particular also i'm interested in how

nutrition can be used to support athlete

performance

i'm particularly interested though in

the effects of polyphenols now

polyphenols are chemicals that are

produced by all plants and they provide

the taste and colour characteristics to

the fruits and vegetables that we

consume in our diets

now the reason that the plants produce

them is because they are antioxidants

and they help to protect the plants from

oxidants that they experience in the

environment for instance like

ultraviolet light

and a great example of this is you can

see the the apple here that on one side

we've got this nice red coloration and

on the back side we've got a green

coloration and now this red color is

produced by the polyphenols that the

apple has produced and laid down in this

area of the apple which is going to be

the sunny side of the apple so when this

was growing on the tree i would bet my

bottom dollar that this was the

sunny side the south south facing side

of the apple and so the the polyphenol

has been laid down to help to protect

the flesh underneath from the

ultraviolet radiation and to prevent the

oxidizing damage that might occur

due to that ultraviolet radiation

there are other examples

that we can provide as well of where

plants use this mechanism so in seeds

for instance so this is a snapshot from

a from a field near me that i took a few

days ago or a few snapshots and what you

can see here a range of different seeds

so here are some some grasses some nasty

stinging nettles

and some other weeds within the field

and you can see that the seeds have this

kind of purpley or ready coloration and

again this is derived from the

polyphenols or anthocyanins that the

plants are producing in the seeds to

help to protect them from the

ultraviolet radiation

and this is obviously really important

because the seeds contain the genetic

material that's going to produce the

next generation of plants

now it's also at the other end of the

life span as well so

here we see the fabulous autumn

spectacle that we get every year when we

get this display of reds and oranges and

golds within the leaves of trees and

autumn and again this is produced

because of the polyphenols and again

anthocyanins that are present within

these aging leaves and these

anthocyanins again help to protect the

leaves from the ultraviolet radiation

and help them to function all the way

through to the point at which they drop

off the plant in the fall

and it's actually a technique that we

use ourselves to some extent as well so

it's very similar principle here where

you can see this

br our tan cyclist legs here

and this is produced by the melanin that

the cyclists are producing in their in

their legs and that's helping to protect

the skin from ultraviolet radiation

because they also have that melanin also

has an antioxidant property very similar

to the polyphenols

now there are many thousands of

different types of polyphenols that are

present within plants within fruits and

vegetables and what i'm showing you on

this slide here is a particular class of

polyphenol called the flavonoids and

within the flavonoids again you can see

there are lots of different sub flam

families um within within the the

flavonoid group of polyphenols but they

all of the polyphenols have a common

chemical structure which is what allows

them to be classed as polyphenols and

what they have is they have this

ring structure within their chemical

structure this is known as a phenolic

ring hence the term polyphenol and they

also have a hydro two hydroxyl groups at

least so this oxygen and hydrogen

contained in groups and that chemical

structure defines them as being

polyphenols

and it's also that chemical structure

that gives them their antioxidant

properties both for the plants and as

we'll see shortly also for us when we

consume them

and the blend of polyphenols that are

contained within different fruits and

vegetables is quite different both in

terms of the amount of polyphenols but

also the blend of different polyphenols

that are that are present within them

and you can see here for example the

anthocyanidins here are really plentiful

within the cherries and the berries

whereas within cacao or chocolate

then we have very high levels of these

flavonols

present within them

and this is really important because not

only do polyphenols provide the color

characteristics as we've seen in some of

the earlier

content they also have an important role

in determining the taste of fruits and

vegetables that we consume so the blend

and amount of polyphenols will influence

how something tastes

and we can actually manipulate that by

changing the growing conditions so the

amount of water that the plant is

exposed to the amount of sunlight the

soil composition and

content all of these factors will

influence the amount and blend of

polyphenols contained within them and

therefore also um the the taste of those

particular fruits and vegetables and

this is something that we can exploit so

the wine buffs amongst you may be

familiar with the concept of

of the terroir of a wine cheers

and this is also exploiting the growing

conditions of the grape so

depending on the environment of the

vineyard the sunlight exposure and water

and soil composition and so on that's

going to influence the blend and amount

of polyphenols that are contained within

the grape and that will also therefore

influence the taste of the wine that is

ultimately produced from from those

grapes

now of course um uh it's producing tasty

food and drink is incredibly important

and i certainly love my food and maybe

the old tipple every now and again um

but the main reason that i'm

particularly interested in uh in in the

in polyphenols in fruits and vegetables

is what the effects are when we consume

them in their diet so how do they

influence the way in which our bodies

function

now we know

that

diets that are high in fruits and

vegetables are good for our health we

know that if we consume diets that are

high in fruits and vegetables we have a

reduced risk of developing conditions

like cardiovascular disease diabetes and

some types of cancer

and we know that the polyphenols

contained within those fruits and

vegetables are an important component of

why fruits and vegetables are are good

for us

and that's partly related of course to

the fact that the the polyphenols

serve as antioxidants for the plants

protecting them against ultraviolet

radiation but in addition to that when

we consume them they also act as

antioxidants and they can also have

anti-inflammatory effects as well within

our bodies

now when we consume a cherry such as

such as we see here in this slide

um

only about five to ten percent of the

polyphenols contained within that cherry

can actually be absorbed into the

bloodstream to then provide those

antioxidant and anti-inflammatory

effects

the rest of the polyphenols then

continue down the gut all the way down

to the large bowel or colon and there

they come into contact with the bacteria

that are contained within the gut you

might have heard of the gut microbiome

and how that can have important effects

beneficial effects on our health

so those bacteria that are contained

within the gut are able to break down

those remaining polyphenols break them

down into smaller molecules that we can

then absorb into the blood

and they can again have those beneficial

effects in terms of antioxidant and

anti-inflammatory effects

but the other really interesting thing

that happens as well is that we're

effectively feeding the bacteria within

the gut sometimes polyphenols are

sometimes called a prebiotic so we're

feeding the bacteria and what that can

do is it can change the amount and the

blend of different types of bacteria

within the gut having a favorable effect

on the gut microbiome which might be

important for health

effects and also for athlete performance

effects as well and we can measure that

by taking small fecal samples that we

can then look for the dna of the

bacteria within the gut within the gut

and we can then identify what bacteria

are there and in what types of amounts

it can give us some really important

information so this is a really exciting

um area of of research

now

bearing in mind these anti-inflammatory

and antioxidant effects of these fruits

and vegetables cherries and berries

chocolates and so on all of these lovely

tasting fruits and vegetables um

they these antioxidants and

anti-inflammatory effects mean that they

can have lots of benefits for us so they

can support healthy aging at one end of

the spectrum so help us to to live

longer and healthier lives and at the

other end of the spectrum polyphenols

can also be used to provide benefits in

terms of athlete performance and the

reason for that is that we know that

oxidative damage which is caused by

being exposed to free radicals and other

oxidants within our environment

contribute to the aging process and they

can also contribute to sort of impairing

athlete performance so by consuming

these polyphenols that have these

antioxidants and anti-inflammatory

effects we can have beneficial

effects on on performance and support

healthy

aging so we and and and other

researchers have have conducted lots of

experiments looking at the effects of

consuming these different types um of

fruit so pomegranates blackcurrants uh

cacao or chocolate cherries and

blueberries and what we've been able to

show is that by consuming um these

polyphenols either in the form of whole

fruits or in the form of supplements and

you can see some examples of these here

so this is a concentrate of a blueberry

so within this glass believe it or not

is the equivalent of around

300 grams of blueberries

all in the form of a concentrate whereas

in this glass here you have the

equivalent of about 250 grams of tart

cherries or sour cherries so all of

which are really rich in in polyphenols

and we have shown that consumption of

these supplements is able to improve

recovery from intensive exercise that

might cause muscle damage and this is

really important for athletes when

they're competing in a tournament

setting where they might have really

limited amounts of time to recover

before they need to repeat their

performance

we've also shown that polyphenols can be

helpful in terms of supporting athlete

performance so

an example of a study that we've done is

we asked athletes to consume a tart

cherry supplement this time in the form

of a of a capsule so this is packed full

of freeze-dried cherry powder and we

asked our athletes our cyclist to

consume these supplements for a period

of seven days and then to complete a 15

kilometer time trial and what we found

was that the cyclists were able to

complete that time trial four percent

faster when they'd consumed the tart

cherry supplement compared to a placebo

supplement and the reason that we think

that this might happen one of the

reasons is obviously the antioxidant

effects and we think that one of the

ways in which this works might be to

improve the supply of oxygenated blood

to the exercising muscle so these

antioxidant effects seem to have a

beneficial effect on on blood vessel

function

now the brain is an example of another

organ that is very highly vascular so it

has a very high requirement for blood

and in fact although the brain

represents only about two percent of our

body weight about 15 to 20 percent of

our blood flow at any one time is being

delivered to the brain

um now unfortunately we know that unfor

as we as all of us age we unfortunately

tend to experience some um deterioration

some decline in our cognitive function

and this might be experienced as a

little bit more forgetfulness all the

way through to difficulties in in

operating in our in our modern world

but we were interested to see whether

polyphenols because of all of these

beneficial effects that i've described

might be able to

improve cognitive function in healthy

older adults

and what we asked our healthy older

participants to do was we asked them to

consume a blueberry supplement very

similar to the supplements i showed you

earlier on

every day for a period of 12 weeks and

we took some measurements from them

before and after that and another group

of participants took a placebo

supplement

and what we found was that the

participants who were consuming the

blueberry supplement

experienced a significant improvement in

their working memory which was obviously

really exciting for us what we also did

in this study was we used a magnetic

resonance imaging scanner using a

particular technique called arterial

spin labeling and this allows us to

measure the amount of blood that is

being delivered to the brain so coming

back to that vascular effect

and

basically how the technique works is the

the um the magnetic

the magnet within the scanner is able to

tag the blood and magnetically tag the

blood as it's coming into the brain and

that allows us to then visualize that

blood as it is perfusing and bathing all

of the cells of the brain in that blood

and that's the image that you can see

here on the screen so the brighter areas

are the areas of of higher blood flow so

we can then quantify the amount of blood

in the brain at any one time and what we

found again is that our participants who

consumed the blueberry supplement

experienced a significant improvement in

their in the profusion of the brain with

blood so a higher amount of blood within

the brain

so i hope that this introduction to

polyphenols and to the human health and

performance benefits associated with

eating them will encourage you to eat

your five a day or maybe even your 10 a

day which would be even better for you

and possibly might encourage you to

study nutrition or sports science or

human physiology related field thanks

very much

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