Episode 2 Britain's Favourite Supermarket Foods

There's one thing we can't argue with

when it comes to our shopping.

We Brits love our food.

In fact, every year we get through an astonishing amount of it.

We drink 60 billion cups of tea.

That's enough to fill the Royal Albert Hall over 150 times.

Every year, we eat over four billion loaves of bread.

That's enough to fill Glasgow's Clyde Auditorium

more than 300 times.

We bought 185,000 tonnes of pasta.

That's enough to fill Leeds Town Hall twice over.

We're used to hearing all the bad news about the food we eat

but I'd like to know the good news.

I'm Cherry Healey and I want to know more about the food we buy,

the supermarket staples that we put in our shopping trolleys

every single week.

I'm keen to see if science can help us

unlock the secrets of our favourite foods.

So in this programme, I'm delving deep into our trolley

of supermarket staples to find out

whether our favourite foods can also keep us healthy.

And to do that, I need some help,

and who better to ask than the good people of Britain?

Across the country, our volunteers are raring to go.

I hang out with some Cardiff cheese fanatics to see

if cheese holds the secret to a healthy smile.

-Look at that!

-Oh, wow!

It hasn't even dropped...

I join the Loughborough hockey squad

to find out if my morning coffee can turn me into a sporting champion.

Getting sweaty!

And I'm with A level students in Reading,

to discover the magic food that could get all of us concentrating.

That's a massive difference!

It's time to test Britain's Favourite Supermarket Foods!

CHEERING

First up, it's a supermarket favourite we are crazy about.

It's the world's most popular hot drink.

The average supermarket sells more than 100 different varieties

and here in Britain we drink 70 million cups of it a day.

What could it be but a good old cup of coffee?

If you're anything like me, the day hasn't properly started

until you've had your first cup.

But what is it about my morning coffee that perks me up

and is it doing me any good?

To find out, I'm on the streets of Bristol.

Here in the South West, they buy more supermarket coffee

than anywhere else in Britain.

How often do you drink coffee?

-Two times a day.

-Three times a day.

-Every other hour.

-Wow!

Why do you drink it?

It gives me a bit of a lift.

Why do you drink it?

To keep me awake...for college.

Is Otto allowed any coffee?

No, not at all.

Otto is hyper enough, thank you very much.

How does it make you feel when you have a coffee?

Like I can take on the world!

It seems our dedicated followers of coffee

are passionate about their daily brew.

Beautiful.

But what is it that gets them going?

-What is in coffee that gives you that boost?

-Caffeine, isn't it?

Do you know how caffeine works?

Not really.

I think it's healthy, isn't it?

No-one seems entirely sure how caffeine actually works.

I want to know the science behind that coffee kick,

so I've invited dietician and coffee guru Dr Sarah Schenker

to help me filter the facts from the fiction.

So, Sarah, like so many people,

I love my cup of coffee in the morning,

but how does caffeine give me that boost?

What's going on in my brain?

Well, it's just a mild stimulant

so it puts you into your flight or fight mode,

so you're ready for action.

There seems to be quite a lot of confusion

over whether caffeine is good for us or not.

One of the things I've always believed is that it's really dehydrating.

That's a really popular myth and one that a lot of people get wrong.

Caffeine or coffee doesn't produce a net loss of water from the body.

So when you drink it, you don't pee out more than you've just taken in.

Can anyone drink as much caffeine as they like?

If you're drinking a lot of caffeine, you know, one cup after another,

one cup of coffee after another,

you're not giving your body a chance for the caffeine to wear off,

then you can put yourself into an agitated state.

There's no official guidance on it but probably between

about anything from one to maybe four or five cups of coffee

throughout the space of the day, would be considered absolutely fine.

But generally it's safe, and as long as I drink it in moderation,

it's a great boost.

Which is great to hear cos it's a good friend of mine in the morning.

Caffeine is a natural stimulant that lots of us use as a pick-me-up,

so it's good to know that it's safe.

But there's one group of people who have a very special use

for that caffeine hit -

elite athletes.

I've come to meet the Loughborough University men's hockey team,

one of the top clubs in the country.

So who here uses caffeine before they do sport?

I use it just before games, generally.

I feel like it gives me an edge during the matches.

Whether it actually does or not, I'm not sure.

Other people I'd heard were using it

and I didn't want them to get a jump on me.

She shoots, she scores! Check it out!

But hockey is just as exhausting as I remember from school.

It's no wonder the boys want to try and get a boost.

Now I'm no athlete but I want to know if caffeine can do for me,

what it's doing for these guys.

To find out,

I've arranged to meet sports scientist Professor Mike Gleeson.

He studies the effects of caffeine on athletic performance

so if anyone can help turn me into Jessica Ennis then it's him.

So I've been speaking to the guys and they tell me

that they use caffeine as a way to enhance their performance.

How does it work?

Well, it has been tested scientifically and the studies show

that if you take enough caffeine at the right time,

then it will improve exercise performance.

So the boys consume their caffeine in either a pill or a liquid form

via energy drinks, but what about a regular cup of coffee?

Can I get the same effects from that?

If you drink enough of the coffee.

That usually probably means two strong cups of coffee to get

the equivalent dose that these guys will be having.

How can we test for that?

Is there a way I can see whether it really, really works?

Yeah. If you come along to the lab tomorrow, with your kit,

then we can find out did it work for you?

The next day I'm off to the lab to test the power of the cuppa.

And I've even roped in Callum from the hockey squad to join me.

Can the humble cup of coffee really give us more get-up-and-go?

So, Callum and I want to know,

does caffeine enhance your physical performance?

How are we going to test that?

Well, you're actually going to do that by running on a treadmill,

to exhaustion.

When you say exhaustion, what do you mean?

Like lying on the floor, being sick?

Well, it will feel hard

and obviously it'll feel harder the longer you go for.

You won't be able to carry on at the speed we're setting it at.

OK, so it's at the point where at that speed and that incline,

I cannot run any more.

Exactly. So one of you will be on decaf,

the other one will be on original coffee.

You won't know which it is, we're not going to tell you.

You'll do the test today and then we'll have you back next week

and we'll reverse the treatments.

Then we'll really see

whether or not coffee actually does improve your performance.

Callum and I gulp down our coffees

but we don't know who's drinking decaf

and who is on full strength caffeine.

An hour later, it's time to take the plunge

and start our test to exhaustion.

MUSIC: "Theme From Rocky" by Bill Conti

Mike's team have set up the treadmill at a speed

and incline to match our fitness levels.

It's getting sweaty.

They know that at a certain point,

we will literally be unable to run another step.

The things I do for the sake of science!

-Great job, well done.

-Well done, brilliant, well done.

I can't wait to find out how far I've run

cos I've never run that hard, ever.

And I can't believe I have to do this again next week.

A week later, Callum and I are back at the lab

to drink our mystery coffees

and run ourselves into the ground all over again.

Mike has reversed the coffees

so that whoever was on the caffeine last week is now on decaf.

We still don't know which is which but have kept our diets

and routines exactly the same

so, if there is any difference in performance,

it can only be down to the coffee.

That was really hard.

That was tough. I could be totally wrong.

Could be all in my mind, which is highly likely

but it just did feel a little bit harder this week.

I don't feel like I ran as far.

Will the results prove the science

behind the power of the caffeine kick?

OK, Mike.

I think that Callum and I have worked hard enough for an answer.

So did the caffeine make a difference to our exercise?

Ta-da!

In the red is what you did on the caffeine, coffee.

In the blue, the decaf.

You both did a lot better.

-Yes!

-You did 30% longer.

I felt like I did. Really.

And you did about 10%.

Right. Why the difference in the percent then?

For somebody who's already athletic and well trained

and maybe used to this kind of thing, it's not likely to make

as big a difference as to somebody who's relatively naive to it.

As someone who plays sport in a semi-professional way,

that 10% must be quite important.

Definitely, yeah. Now that I know that it makes that difference,

it's worth taking it, like you say.

I'm amazed that the coffee improved my performance by 30%.

But scientists have had similar results in other studies

and now think they know why caffeine can have such a dramatic effect.

We get exhausted during exercise

because a chemical message tells our brain and muscles we feel tired.

Caffeine blocks this signal meaning we can keep going for longer.

I've always thought that my morning cuppa gave me a boost.

But now I know caffeine can also help my workout,

I'm a committed coffee convert.

From our favourite pick-me-up to our favourite indulgence.

We Brits love a sugary treat but there's one sweet sensation

we choose over every other and that's chocolate.

On average, each one of us puts away over 22 pounds of the stuff

every year but surely there are no healthy secrets to be found

lurking in my favourite chocolate bar?

Chocolate is my guilty pleasure. I just love it!

It's so creamy and sweet and melts in your mouth.

I just can't stay away from it, even though I know I probably should.

Over the years, chocolate has had a pretty bad rap

but is it really the devil incarnate?

Recently, there have been all sorts of claims

about chocolate's supposed health benefits.

Could this be the light at the end of my chocoholic tunnel?

To find the truth behind the headlines,

I've invited dietician Sian Porter for a very chocolaty day out.

Sian, you have to help me.

I have a really passionate love affair with chocolate.

But some people say it's good, some people say it's bad.

What's going on?

If you think about the raw ingredient, it's a cocoa pod

and eventually it goes through processing and ends up as chocolate.

But as part of the processing, quite often we're adding more fat,

more sugar. So it is something that you are going to keep

as an occasional treat and eat in small amounts.

So the bean in and of itself isn't that bad

but after we've processed it and added lots of sugar and fat,

-it can be very high in calories.

-Indeed.

Why do people think that dark chocolate is better for you?

Well, interestingly, if you look at the data from population studies,

it would seem there is a link between intake of dark chocolate

and reduced risk of certain disease.

But we need more research to really tease out what's going on.

So whilst you're saying there may be some health benefits,

-you're not saying go and eat loads of chocolate?

-Absolutely.

Very disappointed, Sian.

Is there something in my favourite food that could be causing

these health benefits?

To find out, I've come to Nottingham.

Here at the university, Professor Ian MacDonald

is going to show me just how chocolate can impact on my health.

The science of chocolate. Now, that's my kind of studying.

So, Ian, I've always thought of chocolate as something

guilt-ridden and I should be really careful of.

Is there anything you can tell me

that will free me from chocoholic guilt?

There is new research coming out that the cocoa flavonols

that are in some chocolate may have beneficial effects,

as far as promoting heart health and vascular function is concerned.

Cocoa flavonols are natural chemicals found in cocoa beans.

They protect the bean while it's growing

and Ian thinks they may protect us as well.

I want to see the science of the cocoa bean in action!

So Ian and I have scoured the university and managed to find

some volunteers willing to test the benefits of chocolate.

-I'm Jo.

-My name's Adam.

-I'm Beth.

-M name is Hon Jin.

I love chocolate, much prefer dark chocolate.

My favourite chocolate is white chocolate. It tastes so much better.

I probably eat about ten bars of chocolate a week.

I love chocolate. I would eat it every day if I could.

Our intrepid chocolate chompers are off to Ian's lab.

He's already tested their response to white chocolate

which contains no flavonols at all

but today we're taking them over to the dark side.

If the theory is right, the cocoa flavonols in dark chocolate

should have a noticeable impact on their cardiovascular systems.

So, Ian, what's the plan?

OK, so the plan is that first of all

we need to get these four willing volunteers rested.

So the first thing we have to do is just lie down and relax calmly.

And then Liz will use the ultrasound machine to measure

the effect of chocolate upon blood flow in the artery

in the middle part of the arm.

So, basically, they get to lie down, relax and be fed chocolate.

That's correct. They lie down for three hours and behave themselves

and we feed them chocolate in the middle of it.

Tough life!

The chocolate test requires total calm.

Any excitement could cause a change in blood pressure

that might throw the results.

So the room is kept warm and dark

and any potential distractions are removed.

So now I need to leave the room while our volunteers

are being tested because they need to stay completely relaxed.

I don't know what they mean! I can do tranquil...

The test is measuring the flexibility of the main artery

in the arm because this is a prime indicator of a healthy heart.

The more easily it expands in response to increased blood flow,

the healthier the cardiovascular system.

The importance of flexible arteries.

Who knew?

To test whether chocolate has any impact on this flexibility,

Liz constricts blood flow to the arm with a cuff, so that she can

measure how much the artery expands when the blood rushes back in.

She does the test twice.

First, to see the normal functioning of the artery,

then again two hours after our volunteers have eaten 50 grams of dark chocolate.

This is when the cocoa flavonols will have reached

a peak in their bloodstream.

Time for our results.

Have the flavonols made their arteries more flexible?

Has darkness triumphed over the light?

So what have the tests told us?

The tests have told us that all of the volunteers have responded

positively to the dark chocolate,

whereas actually the white chocolate did not have any effect whatsoever.

You can see here that with the white chocolate it stays constant

over the two hour period, whereas with the dark chocolate

it goes up a bit and then a bit more. A substantial response.

So the dark chocolate, in as short a space as two hours,

has increased the flexibility of their arteries?

-Yes, that's right.

-That's quite amazing.

Ian and other scientists have carried out similar experiments

many times with the same results.

In the short-term, the effects of dark chocolate only last a few hours,

but studies suggest there may also be long-term benefits.

At last, a reason to feel good about my obsession.

So as a chocoholic,

how can I incorporate these results into my everyday life?

Well, if we can't persuade you to stop eating chocolate...

You can't.

If you replaced the milk chocolate that you ate by a dark chocolate

that was rich in cocoa flavonols, it certainly wouldn't do any harm

and it may be of benefit in terms of promoting a healthier heart.

If you want to move over to the dark side,

go for a chocolate that's 70% cocoa solid or above.

The higher the percentage,

the more likely it is to be rich in flavonols.

Whilst chocolate may not be the healthiest snack,

if you're a chocoholic like me, and you can't bear to be without it,

why not swap your milk chocolate for a few pieces of dark.

Your heart may thank you for it.

Still to come, I find out whether a simple spice

could stop cancer cells in their tracks?

Seems really powerful stuff!

It's pretty amazing.

And these A level students test a brain-boosting berry

that could help them fly through their exams.

-That's a massive difference.

-Quite a big difference, yeah.

But first, it's one of our trusty reliables.

There are some favourite foods we turn to time and time again.

Kitchen essentials we keep in our cupboards

and put into our shopping bags, almost without thinking.

And if there's one British staple

that's been a favourite for centuries, it's the humble spud.

Whether they're mashed, boiled, baked or fried,

potatoes are a national institution.

Every year, each one of us

chomps our way through 191 pounds,

or 14 stones' worth of potatoes.

That's a lot of spuds!

But not everyone is in love with the spud.

In fact, sales of potatoes have dropped 20%

in the last ten years and are continuing to tumble.

I'm in Scotland where they buy

fewer potatoes than anywhere else in Britain.

Perhaps if I butter up the good people of Glasgow,

they'll tell me why we're spurning the spud.

How do you ladies feel about the potato?

-Pretty boring.

-Pretty boring, yeah.

I think they're too common.

They don't look good.

I do eat chips but I don't make them out of potato.

-What do you make them out of?

-I just get chips...

Oh, obviously they're made out of potatoes. Oh!

It's not an exciting colour.

They look boring.

It's not an amazingly exciting texture.

Just bland.

It's just a potato.

Just a potato.

We seem to think of the potato as the Volvo of the veggie world.

Reliable, but essentially, a little bit dull,

But does it deserve this dreary reputation

or is there more to the simple spud than meets the eye?

I think there could be hidden depths to our tasty tatties

so I've come to the University Of Leeds food science laboratory

where Dr Joanne Maycock puts potatoes through their paces.

So, Dr Jo, I've been on the streets of Glasgow

and people seem to think the potato is just a big, bulky, starchy carb

that you have next to the fun stuff, next to the meat and veg

but really it's not that exciting.

In fact the potato is a really nutritious vegetable.

So it's not just a brown doorstop?

Oh, no. Far from it. It contains carbohydrates

but it also contains protein, lots of minerals

such as potassium, lots of vitamins such as vitamin B6, vitamin C.

You say vitamin C.

When I think vitamin C, I think oranges, you know, lots of fruits.

I don't think...brown potato.

Yeah, so the potato gives you half your recommended daily amount of vitamin C.

Half? From a potato? You wouldn't know it to look at it.

I can't believe that potatoes are chock full of vitamin C

and have more potassium than bananas!

But it turns out they have even more secrets to reveal,

once we get under the skin...

OK, so what we can do is we can use the microscope

to look at what's inside a potato.

I'm assuming more potato.

These larger circles, these are the cell walls

and this shows you the fibre that's in the potato.

It seems to be mostly made up of those.

So potato is really high fibre.

Potato is high fibre.

And then also here, this is the potato skin.

But the cells are a lot more dense, they're smaller

and there's a lot more of them.

So does the skin have the highest amount of fibre in it?

The skin does have the highest amount of fibre in it.

So what you need to do is, when you have your jacket potato,

-make sure that you always eat the skin.

-Nice!

It's the best bit as well! Cos it's crispy.

It's the tastiest bit.

Why do you need fibre?

So fibre's good for you because it makes you feel full.

It also has roles in helping reduce obesity, high blood pressure,

heart disease. There's lots of reasons why we should be eating fibre.

The magic of potatoes! It just never fails to astound me.

A fibre rich diet keeps your whole intestinal system running smoothly

and let's face it, who doesn't want a happy bowel?

And scientists think it may also help to protect us from cancer

and high cholesterol.

But when I think of fibre, I think of bran or brown rice.

I want to know if a potato can hold its own against something

we think of as a real high fibre hitter.

So Joanne has devised a fibre fight!

MUSIC: "Eye Of The Tiger" by Survivor

In one corner we have the health-food favourite,

a bowl of brown rice.

In the other corner, a lowly baked spud.

We're going to measure the fibre content of each

and find our champion.

I think most people looking at these would say that the rice

has the highest fibre content.

OK, let's find out.

OK, so we need to put our safety specs on.

Serious, sciencey stuff beginning. OK.

To find out which food is our fibre hero,

Jo needs to separate out the fibre from everything else

and it's trickier than it sounds!

Firstly, our two contenders are dried out and ground down.

-You cremated the potato?

-That's right.

So that is potato powder.

So that's our potato and that's our rice.

Next, Jo adds liquid enzymes which will reveal our precious fibre.

Our bodies find it hard to digest fibre so most of it passes

straight through us helping to keep us regular!

And in the same way, the enzymes can't digest it either,

so it gets left behind in the beaker.

So you're going to add enzymes and they're going to eat away

-all of the things that you don't want to measure.

-That's right.

So you'll just be left with the fibre. I actually understand that.

Down in one? Dare me?

Go on then!

Finally, our beakers of fibre are filtered

and dried out in the oven.

It might not look like it but this is what's left of our potato

and brown rice samples.

This is the pure fibre content.

So we're going to weigh them and find out who the winner is.

Ta-da! Bon appetite!

OK, so I've worked out the results.

The rice has got 3.55% fibre

and potato has got 5.44% fibre.

So that's one and a half times greater amount than the rice.

So the potato beats the brown rice hands down?

Yes.

I'm so surprised. The fact that it's that much more is amazing.

It's a killer blow for the brown rice.

We have our champion.

So it turns out that the potato is a wonder food in disguise!

Now that I know the truth,

can I rescue this unsung hero of the veggie world?

Can we, the people of Britain, fall back in love with the spud?

Back in Glasgow I've devised a cunning plan

to show people just how much of a healthy hero the potato really is.

These plates of food all weigh exactly the same.

One of these plates of food has more fibre than any of the others,

50% of your daily recommended dose of vitamin C,

more than 90% of your daily requirement of potassium

-and less than one gram of fat.

-Right.

Which do you think it is?

-I'd love it to be the chocolate cake!

-Wouldn't we all, Lilly?

-I think it's the carrots.

-Broccoli?

Broccoli?

I think the potato, as long as you eat the jacket.

I'm going to tell you that your wife is right.

-Oh, dear. Oh, dear!

-So you can listen to me in future.

-You'll have to listen to her now.

-Yes, dear. Yes, dear.

We've all heard about supposed super foods

making all sorts of nutritional claims and boasts.

But it turns out we've had a genuine superhero

sitting in our shopping trolley all along.

Next up, I'm looking for the secret power

in one of our all-time creamy favourites.

Every year, 1.8 million British dairy cows

work their udders off to produce the 13 billion litres of milk we use

for everything from butter on our toast to the cream in our coffee,

because Britain is a nation that is doolally about dairy.

There's one dairy delight we just can't seem to get enough of.

In fact, we eat a staggering 700,000 tonnes of it every year.

It is, of course, cheese.

There's no doubt we love our cheese

but what are our top five absolute favourites?

In fifth place it's everyone's stinky delight, blue Stilton.

Fourth place goes to the Double Gloucester

and third to the Red Leicester.

The runner-up in second place is mozzarella -

must be all those pizzas.

But in first place it's the trusty cheddar. No surprise there.

But did you know we actually eat six times more cheddar

than any other cheese?

But what is it that makes cheese so irresistible

and does our dairy addiction do us more harm than good?

To find out, I've come to Wales.

Here at Cardiff's famous castle,

they host the biggest British cheese festival.

For one weekend only, thousands of fromage fanatics

from across the globe have converged on this spot.

And if anyone should know why we love cheese it's them!

-It's the best thing in the world.

-It improves any meal.

Forget fast food. An apple and a lump of cheese. Job done.

Clearly we love our cheeses but do they love us?

What is it in cheese that people are worried about?

They're worried about the fat.

I would rather not think about that.

-Calories?

-Waistlines have something to do with it when you're our age.

There's a lot of fat in it. And dairy.

Is our delicious dairy actually a dieting disaster?

Perhaps cheese-lover and dietician Sue Baic

can WHEY in on this cheesy conundrum.

Sue, are you a cheese fan?

I'm a big cheese fan. It's a great food.

It's full of protein and it's also full of calcium,

which is necessary for strong bones and teeth.

But people are worried about whether cheese is healthy or not.

It's very high in fat.

Yeah, well that's true. Cheese is about a third fat.

And quite a large proportion of that is saturated animal fat,

the one that puts our cholesterol levels up.

But if you keep your portion sizes reasonably moderate, then it's not a problem.

So something like around 50 grams or slightly bigger than that

sort of sized matchbox, is what a portion size would be.

That doesn't look very much.

It's not huge but if you think about lots of tricks to make it go further.

You can use a very mature cheese and because it's got a stronger flavour,

you get away with using less.

-Extra mature cheddar will go a lot further.

-Or a stinky stilton?

-A stinky stilton.

-So you feel like you've really had some cheese but you haven't had too much.

-Exactly.

So it's packed full of goodness, but beware of portion control.

Anything else we should know about cheese?

Not only is cheese a good source of calcium for our bones and teeth,

but there is some research that shows that cheese can help

our dental health in other ways, actually.

-So cheese can also help protect our teeth?

-It can.

-Amazing!

Can a cheesy treat really help protect my pearly whites?

To find the answer I've called in Professor Alastair Sloan

from the Cardiff University Dental School for assistance.

When it comes to teeth, he certainly knows the drill.

So I'm intrigued to find out how cheese can help with dental health.

To understand that, we need to understand what happens in the mouth

when you eat foodstuffs that can cause erosion of your teeth.

Everyday foodstuffs such as oranges and lemons and fruit juices,

including our favourite cola drinks, sadly even wine,

they contain dietary acids in quite high amounts

and that can cause erosion of your dental enamel.

So these cause erosion of our teeth.

Not tomato sauce. No!

Sadly even tomato sauce is quite acidic.

I can see here that you have a penny and a glass of orange juice.

Are you going to do the classic childhood experiment?

Very simple experiment.

A very grubby two pence coin, very dirty.

Three days ago we dropped a very similar coin

into this glass of everyday orange juice.

-And if you look carefully, what you can see...

-Shiny!

-Very shiny.

-Good for the penny...

Great for the penny. But imagine if that was your actual tooth.

The acids there have cleaned the penny

and they do the same thing to your tooth enamel.

And that enamel softens.

-And erodes.

-And erodes.

-So how does cheese prevent the erosion?

Cheese stimulates the body's natural defence mechanism in the mouth

and that's the production of saliva.

To test Alastair's theory, we need a volunteer who likes cheese.

Where on earth will we find one of those?

She looks really smiley.

Excuse me. I'm assuming you quite like cheese.

I do, I'm Lady Cheddar.

-How would you feel about joining me for a cheesy experiment?

-I'm up for that.

With the help of our lovely cheesemonger,

Alastair is going to test whether a piece of cheese

can protect our teeth from the ravages of acidic food.

First he needs to get a normal reading

of the state of Susan's mouth.

If you don't mind spitting into this tube for me.

-I need lots of spit.

-Lots of spit.

And then we can make sure the pH of your mouth is normal.

Is normal. OK.

-SHE LAUGHS

-I know. Don't look. Don't look.

A pH scale measures the acidity of a substance, a food,

or in our case, Susan's spit.

-This machine tells us what the pH of Susan's mouth is.

-Absolutely does.

And a figure that's around seven means your mouth is at neutral pH.

It's very normal.

Numbers below seven means your mouth is more acid like.

And at 5.5 and below, enamel will start to dissolve.

The orange juice should have an instant impact on Susan's mouth.

-Spit for me again, please. A nice, big, healthy sample.

-So much spit!

Loads of spit.

OK. Let's take a look and see what we've got on this sample here.

The probe goes in. Wow!

-Wow!

-So we are now down to 4.75 which is below that critical 5.5 pH.

Just from that much orange juice.

Just from two big mouthfuls of orange juice.

As long as Susan's mouth remains acidic from the orange juice,

her teeth will be under attack so Alastair continues to test her spit.

Surely she's going to run out!

-We can't watch. It doesn't help.

-She'll get spit shame.

It takes almost 20 minutes for Susan's mouth to return to its normal pH level.

So what has all that spitting told us?

-Well, first of all it's told us that Sue is very normal.

-Yay!

And that actually what's happening in her mouth is she drank

the orange juice and her teeth were under attack from the acid.

Once Susan's mouth has returned to neutral,

it's time to run the test again.

But this time we're bringing in the big guns

in the form of a small piece of cheddar.

Can cheese really save Susan from an acid attack?

So, the cheese round! So what does Susan do now?

We need to have some orange juice, as we were.

And as soon as you've drunk that,

we need you to eat the cheese straightaway.

This is the nice bit of the test, yeah?

I feel like a mouse now.

What we hope to see is that the pH

should be above that critical pH of 5.5.

-But the proof will be in the spit.

-Will be in the spitting.

-OK. I'll look away.

-Little bit more.

You and your spit! You love it.

I'm just going to keep my eye on the dial.

-Well, look at that.

-Oh, wow!

-That is amazing, isn't it?

-Hasn't even dropped.

So before, it took nearly 20 minutes for Susan's mouth

to reach a neutral point and it's now taken...

-Less than a minute.

-Immediately, almost.

Pretty much an immediate response.

So eating a piece of cheese can really help to bring

-your mouth back to neutral pH, which stops acid erosion.

-Absolutely.

So what's going on?

How does the cheese counteract the acid in our mouths so quickly?

Firstly, the chewiness and flavour of cheese make it one

of the best foods there is for stimulating saliva.

And saliva is the body's own defence system, neutralising the mouth against acid.

But the calcium in cheese may also work directly on teeth,

replacing minerals and repairing some of the damage of erosion.

In theory then, after you've had a meal,

it's better to have a piece of cheese say than brush your teeth?

You should never brush your teeth immediately after eating.

You saw with Sue and the orange juice alone,

it took 20 minutes to recover back to neutral.

So if you brush your teeth inside that 20 minute period,

what you're doing is brushing acid around your teeth.

You must always wait at least 20 minutes before brushing

your teeth after eating.

Or, as we can see, a small piece of cheese may improve that process.

Did you have any idea, Susan, that your beloved cheese had so many wonderful properties?

No, I didn't. No, that is absolutely brilliant.

-It's not just a lovely way to end a meal but it's practical too.

-Absolutely.

-I love it.

It's fab.

Who would have thought something so delicious

could help protect my precious pearly whites?

As a nation, our favourite foods are changing

as we become ever braver in our eating habits.

Our supermarkets are now full of aisles

devoted to exotic foods and spices.

But our absolute favourite spicy dish is curry.

In fact, it's estimated that we spend an astonishing £4 billion on it every year.

I love a curry.

But I've always thought they were bad for you.

Could my Friday night favourite have any health benefits?

I want to know what's in a curry and is it any good for me?

I've come to Leicester in the heart of the Midlands.

This is Britain's curry central,

where there are more curry houses than anywhere else in the country.

Where better to discover what's really inside a curry

than one of Leicester's famous Belgrave Road curry spots?

And I've invited along nutritionist Azmina Govindji

to tell me if there are any wonder ingredients in curry that could boost my health.

Azmina, I've always thought curry was really indulgent.

Well, when you think of a curry

you visualise that orange layer of oil on the top, don't you?

But there are things you can do to make your curry really healthy

and some of the traditional spices and ingredients can actually be good for you.

I have to confess, I've never made it at home

cos I've always thought it was really complicated.

Most curries have the same basic steps, it's easier than you think.

Chef Hamid is going to take us through

the creation of a curry, step by step.

He's going to start off with his oil or ghee.

You can use sunflower, corn or rapeseed oil.

-Next thing that's going in...

-Are the onions.

And the onions give you that lovely texture

and creaminess that most curries need.

And what's interesting is that onions are one of the best sources of a substance called quercetin

and scientists are getting really interested in quercetin.

While Hamid cooks up a storm, I'm off to the local vegetable market

to investigate the power of quercetin with Dr Steve Alexander.

He's a man who definitely knows his onions.

So, Steve, I know onions contain this magical compound. What is it?

It's a compound called quercetin, which are naturally occurring

in fruit and vegetables and which is part of our diet.

And how can it be helpful for our health?

Well, the hypothesis goes that if you have quercetin over a number of years,

that what you'll end up with is a much better cardiovascular system.

Your decline that occurs naturally with age will be slowed down.

So running up and down stairs is something you can do when you're 20 and less easy when you're 70.

Well, even when you're 30 it becomes hard!

So, can you tell which onions have the highest levels of quercetin?

We can but not without doing a little bit of bio-chemistry.

Let's do it.

So what I did last night was I took the same amount

of each of these three different sorts of onions

and blended them with just a hand held blender at home.

Mmmm, delicious.

So this is red onion juice, white onion juice

-And spring onions.

-..and spring onion juice.

None of which I'd like to taste.

So what are you going to do with them now?

There's a dye reagent I can add to them

which will react with the quercetin

and generate a colour, which should be a dark blue.

So this dye will show us

the levels of quercetin in each of these test tubes.

Yep. Indeed.

So you can see that the red onion has the most quercetin in it

because it's gone the darkest colour, compared to the other two.

In fact when Steve tested these samples in the lab,

he found the red onion had up to 50% more quercetin than the other two.

So if I want to boost my quercetin levels,

I should use red onion in my curry?

Red onion will certainly give you a lot more than the white onion or the spring onion.

-So a curry a day?

-Could be very good for you.

Maybe not that often though!

The power of the onion!

Back in the kitchen, it's reaching curry crunch time

as more crucial ingredients are added to the mix.

So, Azmina, it's really starting to look like the base of something now.

Your cumin, your onions, your ginger,

garlic and the tomatoes have just gone in.

The interesting thing about tomatoes is that it's one of the few foods

that gets better for you once you cook or process it.

Tomatoes are packed full of an important nutrient called Lycopene,

which can protect the skin against UV rays

and which scientists think may cut the risk of certain diseases.

The cooking process can actually increase Lycopene content by 50%.

This is where it starts to get interesting.

It really smells like a curry.

You've got your chilli, coriander, cumin powder and your turmeric.

-Really colourful.

-Aren't they? And spices like this are the basis of most curries.

There's a lot of really good research on spices.

In fact here in the University Of Leicester,

there's a group of academics particularly interested in turmeric.

To find out more about turmeric's spicy secrets,

I've invited Dr Leonie Norris to join me at the curry house.

So, Leonie, I've heard turmeric has some amazing properties.

But it doesn't really look like much.

It looks like a mouldy potato.

It does at the moment but actually what we're really interested in

is what's inside turmeric, which is something called curcumin.

It's curcumin that gives turmeric this lovely bright yellow colour.

And it's what stains your fingers if you use it.

And chopping boards and everything else.

-Everything it touches!

-That's curcumin.

And why are you interested in curcumin?

Well, we're interested in the actual anti-cancer properties of curcumin.

Some studies have shown actually that Asian populations

who consume a lot of turmeric in their diet

have a lower incidence rate of bowel cancer.

That's amazing that curcumin might be able to prevent cancer.

But how does it actually work?

What we have here are some cancer cells that are untreated

and here we have cancer cells that have been treated with curcumin.

Hopefully what you'll be able to see is that the curcumin-treated cancer

cells are moving a lot slower

and generally appear to be a lot less happy.

So the curcumin is really slowing down the spread of the cancer?

That's certainly what we believe in the lab.

It appears to be inhibiting cell growth

and it can cut off blood supply to the cells,

which inevitably then will cause cell death.

-It seems really powerful stuff.

-It's pretty amazing.

It's still too early to know exactly how much turmeric is needed

in the diet to have an effect, but with clinical trials now under way,

Leonie and her colleagues believe their research

could lead to a real breakthrough in combating bowel cancer.

From the heart-helping power of the onion to the cancer-busting properties of turmeric,

it seems curry is brimming with nutritional secrets.

I'm amazed that curry can pack such a powerful health punch.

And now that I'm a curry chef extraordinaire,

I'll definitely be making it more often.

As the nation's tastes have changed, so too have our favourite foods.

We now eat almost 50% more fresh fruit than we did in the 1970s,

including far more exotic fruits.

But of all our fruity favourites, there's one I have a real crush on.

It's berries!

Strawberries and cream, raspberry jam, blackberry crumble.

It's the sweet taste of British summer.

In fact, berries of all kinds are a firm national favourite

and every year we get through a staggering 140,000 tonnes of them.

That's enough to make a summer pudding three times the size of the Royal Albert Hall!

But what is it that makes these juicy gems so special?

It's the juiciness of them. They're so lovely.

You just bite into them and "phssh".

What do you like about strawberries?

They taste a bit yummy, don't they?

-How do you like to eat your berries?

-We have them in our breakfast.

If we have a lot left over, I do make jam with the children.

But our favourite summer fruits aren't just tasty,

they also have a powerful nutritional secret.

One man who knows more about the benefits of the berry than most is Professor Jeremy Spencer.

He's spent years uncovering their potent powers.

So other than being delicious and really versatile,

what is so good about berries?

Well, berries, like other fruits and vegetables,

contain vitamins and minerals which are good for our health.

But what makes them unique is that they contain

some compounds at quite high concentrations called flavonoids.

Flavonoids are natural chemicals made by plants

for their own protection.

They protect the plant against things like UV light and insect attack.

And when we eat them, they also promote health effects in us.

So we've been focusing on blueberries

because they contain a profile of about six different flavonoids.

So you think that blueberries are the most potent of the berries?

We do certainly find that they can have some very significant effects

on blood pressure, on blood flow and also more recently brain health,

-things like attention and processing speed.

-What?

So you're saying that the blueberry can help your brain function?

That's right.

-And not only that but it does it within about two to five hours after consuming them.

-What?

That's quite a big claim, that eating blueberries

can increase my concentration in quite a short space of time.

I will believe it when I see it.

It's no surprise to me that blueberries are healthy,

but the idea that they could boost our brain power

sounds like science fiction.

I want to test this remarkable theory for myself

so I've come to Reading, where Jeremy conducts his research.

And where better to try it out, than the local secondary school?

To see whether Jeremy's theory really does hold true,

we've roped in some volunteers.

These are all sixth form students

from Reading's John Madjeski Academy

and they're in the middle of the most important school year

of their lives so, if anyone could do with a brain boost, it's them.

-No pressure!

-THEY LAUGH

-How do you find exams?

-Stressful!

Do you eat or drink anything to help you with your concentration?

Lots and lots of energy drinks.

Water, fruit...

Sweets, sugar.

-If there was something that could give you a bit of a boost, would that be appealing?

-Yep, definitely.

They don't know it yet, but these kids are our blueberry guinea pigs.

With their help we're going to find out

if these tiny berries can really make a difference.

First, the class is randomly divided into two groups - red and green.

Thank you so much for coming today and being part of our experiment.

It's really important that you focus on the tests you're about to take.

Next, they're given a series of specially devised exams

to test their word recognition, concentration and memory skills.

They're so focused on this. Proper exam conditions.

Really focused and really quiet and really taking it seriously.

So what's happening right now?

They're sitting a series of tests which will asses different

functions in their brain, so their memory,

their speed of processing and their ability to correctly identify targets.

OK, so the purpose of this test is to see how the kids,

are able to concentrate normally.

-Just their normal brain function.

-Yes, exactly.

While our students finish their brain tests,

I get to work on the next stage of the experiment.

I'm making them a very special mid-morning snack.

Turn that one on.

And we can start adding the milk to that.

The red group are getting a super-charged blueberry smoothie,

packed full of flavonoids.

'The green group are also getting a smoothie but theirs is banana.'

Delicious but not a brain-boosting berry in sight.

None of our students know which drink they're getting or why

but Jeremy thinks the secret powers of the blueberry

could improve those exam scores later in the day.

I've tried both of them and I can say that they are both delicious.

Oh, you've got a long way to go!

-Enjoying it?

-No.

Finished? Yes.

Oh, there's a bit more in there.

Nice try, nice try.

They may not have loved them but at least they drank them!

Thank you so much for taking part in part one of our experiment

and for drinking the delicious drink, which so many of you loved.

With the smoothies polished off,

we now need to give the berries time to work their magic.

Jeremy's research has shown that it takes roughly four hours

for the effects to reach their peak.

But what is it that the blueberries do?

What is actually going on inside our students' heads?

The scientists have discovered that the flavonoids in blueberries

are absorbed into the bloodstream

and then cause an increase in blood flow to the parts of the brain

responsible for memory,

concentration and attention to detail.

It's this effect that Jeremy hopes will transform our teenagers

into bright-eyed brainiacs.

So that's the theory but has it worked?

It's been four hours since the students had their smoothies,

so now it's time for round two of the experiment.

Let's see if those drinks really had an impact.

Our valiant volunteers are given another series of brain tests

similar to the ones they sat this morning.

This time of day is when many students start feeling tired.

Will blueberries be able to triumph

over even the classic afternoon slump?

So they're crunching the numbers now,

going through all of the results.

Fingers crossed it's going OK.

OK, Jeremy. Put me out of my misery.

Do blueberries really improve our brain function?

Well, you'll be very pleased to know

that in the tests so far processed today,

the blueberry outperformed the banana in every case.

-If you look at the...

-So it really works?

-It really works.

That's amazing.

In fact, overall,

the blueberry smoothie drinkers did 11% better in the afternoon tests

compared to their morning performance.

While the banana group didn't improve at all.

-That's a massive difference!

-Quite a big difference, yes.

The results of our study were so impressive

that Jeremy and his colleagues hope to publish them

as part of an academic paper,

along with similar findings from their other experiments.

And for our students, an 11% improvement could be the difference

between a pass and a fail in their A-level exams.

They ate two portions or 200 grams

of fresh blueberries in their smoothies

but the flavonoids should be just as effective in frozen berries

or even blueberry puree.

It seems incredible that something so small

can have such a dramatic effect.

So the next time I want to give my brain a boost,

I know what I'll be reaching for.

I set out to find the healthy secrets

hidden in our favourite foods.

And with your help, I've discovered that our supermarket staples

have powers we'd never have imagined.

I love the fact that coffee can help with my gym workouts.

I have a new-found respect for the humble potato.

And I'm amazed that eating blueberries

can boost my concentration.

This is the stuff we take for granted,

so it's good to know our favourite foods can still surprise us.

Subtitles by Red Bee Media Ltd