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5:03
Transcript
0:06
Picture warm, gooey cookies,
0:09
crunchy candies, velvety cakes,
0:12
waffle cones piled high with ice cream.
0:14
Is your mouth watering?
0:16
Are you craving dessert?
0:17
Why?
0:18
What happens in the brain
that makes sugary foods so hard to resist?
0:23
Sugar is a general term
used to describe a class of molecules
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0:27
called carbohydrates,
0:28
and it's found in a wide variety
of food and drink.
0:31
Just check the labels
on sweet products you buy.
0:34
Glucose, fructose, sucrose,
0:36
maltose, lactose, dextrose, and starch
0:39
are all forms of sugar.
0:41
So are high-fructose corn syrup,
0:43
fruit juice, raw sugar, and honey.
0:46
And sugar isn't just
in candies and desserts,
0:49
it's also added to tomato sauce,
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0:51
yogurt, dried fruit,
flavored waters, or granola bars.
0:55
Since sugar is everywhere,
it's important to understand
0:58
how it affects the brain.
0:59
What happens when sugar hits your tongue?
1:02
And does eating a little bit of sugar
make you crave more?
1:05
You take a bite of cereal.
1:07
The sugars it contains activate
the sweet-taste receptors,
1:10
part of the taste buds on the tongue.
1:12
These receptors send a signal
up to the brain stem,
1:15
and from there, it forks off
into many areas of the forebrain,
1:19
one of which is the cerebral cortex.
1:21
Different sections of the cerebral cortex
process different tastes:
1:26
bitter, salty, umami,
1:27
and, in our case, sweet.
1:29
From here, the signal activates
the brain's reward system.
1:33
This reward system is a series
of electrical and chemical pathways
1:37
across several different
regions of the brain.
1:39
It's a complicated network,
1:41
but it helps answer a single,
subconscious question:
1:44
should I do that again?
1:45
That warm, fuzzy feeling you get
when you taste Grandma's chocolate cake?
1:49
That's your reward system saying,
1:51
"Mmm, yes!"
1:52
And it's not just activated by food.
1:55
Socializing, sexual behavior, and drugs
1:57
are just a few examples
of things and experiences
2:00
that also activate the reward system.
2:03
But overactivating this reward system
kickstarts a series of unfortunate events:
2:08
loss of control, craving,
and increased tolerance to sugar.
2:13
Let's get back to our bite of cereal.
2:15
It travels down into your stomach
and eventually into your gut.
2:18
And guess what?
2:19
There are sugar receptors here, too.
2:22
They are not taste buds,
but they do send signals
2:24
telling your brain that you're full
2:26
or that your body should
produce more insulin
2:28
to deal with the extra sugar
you're eating.
2:31
The major currency
of our reward system is dopamine,
2:34
an important chemical or neurotransmitter.
2:37
There are many dopamine
receptors in the forebrain,
2:39
but they're not evenly distributed.
2:41
Certain areas contain dense
clusters of receptors,
2:44
and these dopamine hot spots
are a part of our reward system.
2:48
Drugs like alcohol, nicotine, or heroin
2:51
send dopamine into overdrive,
2:53
leading some people
to constantly seek that high,
2:56
in other words, to be addicted.
2:58
Sugar also causes dopamine to be released,
though not as violently as drugs.
3:03
And sugar is rare
among dopamine-inducing foods.
3:06
Broccoli, for example, has no effect,
3:08
which probably explains
3:10
why it's so hard to get
kids to eat their veggies.
3:13
Speaking of healthy foods,
3:14
let's say you're hungry
and decide to eat a balanced meal.
3:17
You do, and dopamine levels spike
in the reward system hot spots.
3:21
But if you eat that same dish
many days in a row,
3:24
dopamine levels will spike less and less,
eventually leveling out.
3:28
That's because when it comes to food,
3:30
the brain evolved to pay special attention
to new or different tastes.
3:34
Why?
3:36
Two reasons:
3:37
first, to detect food that's gone bad.
3:39
And second, because the more variety
we have in our diet,
3:42
the more likely we are
to get all the nutrients we need.
3:45
To keep that variety up,
3:47
we need to be able
to recognize a new food,
3:49
and more importantly, we need
to want to keep eating new foods.
3:53
And that's why the dopamine levels off
when a food becomes boring.
3:57
Now, back to that meal.
3:58
What happens if in place
of the healthy, balanced dish,
4:02
you eat sugar-rich food instead?
4:04
If you rarely eat sugar
or don't eat much at a time,
4:07
the effect is similar
to that of the balanced meal.
4:09
But if you eat too much,
the dopamine response does not level out.
4:13
In other words, eating lots of sugar
will continue to feel rewarding.
4:17
In this way, sugar behaves
a little bit like a drug.
4:21
It's one reason people seem
to be hooked on sugary foods.
4:24
So, think back to all those
different kinds of sugar.
4:27
Each one is unique,
but every time any sugar is consumed,
4:30
it kickstarts a domino effect in the brain
that sparks a rewarding feeling.
4:35
Too much, too often,
and things can go into overdrive.
4:38
So, yes, overconsumption of sugar
can have addictive effects on the brain,
4:42
but a wedge of cake once
in a while won't hurt you.
— end of transcript —
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