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- Hi, everybody.
Welcome back to our Fundamentals
of Nutrition channel.
Today we're going to talk
about the scientific method.
The scientific method is a
way that we gather evidence
around nutrition so we can answer
our burning nutrition questions,
questions that you might
have or that you might get
from friends and family.
Things like, "Is chocolate good for me?"
"Should I be a vegan?"
"What's the best way for me to feel
"like I have the most energy?"
All of those types of
questions are really important
and they're answered by
gathering scientific evidence
using the scientific method.
So what are the steps of
the scientific method?
Let's find out.
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So the scientific method, the first one,
first step is that you ask a question.
So let's use this question
as our overarching question.
Is eating ice cream healthy for me?
Let's say that you really wanna figure out
if that is true or false
because you really love
ice cream, perhaps.
So that's our first step.
The second step is to make
a hypothesis or prediction.
A hypothesis is just what
you think will happen.
And hypotheses are usually
based on previous information
that you know or your
personal experience, even,
but usually based on previous research
that might point you a certain direction.
So my hypothesis to our question
is eating ice cream healthy for you,
my hypothesis is people
who eat ice cream every day
will be happier and have better
markers of metabolic health,
like their blood cholesterol,
their blood sugar,
than those who don't.
So I'm really going all in and saying
that eating ice cream every
day is gonna make you happier,
so your mental health will be better,
and it's gonna make you
metabolically healthier,
so your physical health will be better.
And I may have based
this on previous research
that I've done.
Or I may have just wanna
believe that this is true.
It's better to base on previous research.
But a hypothesis is just a prediction.
Our third step, then, is
to conduct an experiment.
And there's really four
types of research experiments
that are commonly used in nutrition.
The first type is a lab study,
and we're gonna talk about
each of these types going forward.
A lab study, then we have a case study,
an epidemiological study,
or an intervention study.
So let's talk a little bit
more about each of these types
and how they might work
for our ice cream question.
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If you're doing a lab study,
you might have two groups,
usually of animals,
in this case, mice.
So you have one group of mice
and a second group of mice,
same type of mice.
And so what you might do
is for one of the groups,
you might feed that group
three servings of ice cream
every single day.
The other group might get
no ice cream every day.
And you might monitor the
mice for three, six months,
something like that.
And at the end of your time period,
you're going to ask yourself,
and you're going to do
measures with the mice
to figure out which group
of mice are happier,
which group of mice have
better metabolic health.
There's ways you can
measure mouse happiness,
and then you can take blood cholesterol,
you can look at the hearts of the mice,
you can look at the blood
sugar response of the mice
to figure out their metabolic health.
Oftentimes we see
nutrition studies in mice
when doing them in humans
is not really feasible yet,
or where you might have to really look
at the inside of a heart or another organ,
where you can't really
cut a human up to do that.
And I know there's animal rights issues
with lab-based research,
and some people really
don't like to do that.
But we do find out a lot
of fundamentally important
nutrition information from
lab studies in animals.
But one thing to remember with that
is that animals are
not the same as humans.
So just because something is
proven to be true in an animal
does not 100% mean it will
then be true in a human.
So lab studies are important,
but they are not the be-all,
end-all of figuring out
how a nutrient is going to impact a human.
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The second type of study that
you might do is a case study.
So in a case study,
you really usually follow one individual.
So here's an individual.
It looks like she likes ice cream.
So you recruit this individual.
And you feed this individual
three ice cream cones
every day for six months.
So you're talking about one person,
and she's eating all of this
ice cream for six months.
And then you ask, after six months,
is she happier than she
was at the beginning
and does she have better metabolic health
than she did at the beginning.
So you might give her a
psychological questionnaire
to determine her happiness.
And you might look at her blood sugar
and her blood cholesterol to
determine her metabolic health,
measures like that.
What you have to remember is
that you've only used one individual.
So even if you find that she is happier
after eating ice cream
every day for six months,
that might not apply
to a larger population.
Really important to keep
in mind with a case study.
So case studies can alert us
to kind of interesting findings
or unique findings, but
they don't always apply
across a population.
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The epidemiological studies
look at a whole population.
And you can really define the
population however you want.
So it could be a
population of UVM students.
It could be a population of Vermonters.
It could be a population
of the whole United States.
So in this case, we're looking
at the whole United States.
And often, an epidemiological study,
they might administer a
survey to everybody they can,
or a sample population
in the United States.
So they'll randomly choose
Americans to send surveys to.
You may have been involved
in an epidemiological study before
or a political study that
operates in a similar way,
where they send you a survey
or they ask you your thoughts.
So you send a survey
to everybody in America
and you ask, "How much
ice cream do you eat?"
"How happy are you?"
and "What health conditions do you have?"
And so then, they send the surveys back
and you figure out,
you figure out associations
between how much ice cream
people are eating and their happiness
and their metabolic health.
So you might find that people
who eat the most ice cream
are different than people
who eat the least ice cream.
And you might compare them,
those who eat the most
with those who eat the least.
But what's really important
is that you have to realize,
and this is like jump
up and down important,
any associations you find
between who eats the most ice cream
and their happiness or healthiness,
that is a correlation,
that is an association.
It does not mean, you did not
find that eating ice cream
causes you to be happier with
an epidemiological study.
That's just not possible
in that type of study
because what could have
happened if you found
that people who eat the most ice cream,
and those people were associated
with happier and healthier outcomes,
there could be other
factors involved there.
So there, in that relationship
that the arrow is indicating
that there's this
relationship between people
who eat the most ice cream
and being happy and healthy,
there's other things at work.
So they could be of a
different socioeconomic status.
They could have different
education levels.
They could be of different ages.
Sex could be at work.
They could be eating a
certain kind of ice cream.
They could be doing other
diet and health habits
that impact this relationship you found
between eating the most ice cream
and being happy and healthy.
So in an epidemiological study,
you have to really try to
control for those variables,
and there's statistical
techniques you can use
to try to do that.
But you'll never be able to say
from that type of study design
that eating ice cream causes
you to be happy and healthy.
If you want to look at causation,
you really need to do what's
called an intervention study.
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Two groups, and you do this randomly.
So the groups are randomly assigned.
Whether you're in Group 1 or Group 2
is usually assigned by a computer.
And because you've randomly assigned
this larger group of
people to these two groups,
you can assume there are
no fundamental differences,
on average, between the two groups.
So their education
level should be similar.
Their SES status should be similar.
The racial ethnicity
breakdown of the group
should be similar.
The sex breakdown should be similar.
So they should be able to be compared
because all of the factors,
the individual factors
between the groups are
kind of eliminated as factors
because of this random assignment.
So then you can take the two groups,
and Group 1, you might feed them
three ice cream cones a day.
Group 2, you might say,
"You're not getting ice cream at all,"
and then you monitor them over six months.
At the end of six months,
you then look at the data,
and you might find the
same thing you found
in epidemiological study,
that people who eat the most ice cream
are happier and metabolically healthier.
But because you did this
randomization to the groups
and then you had a controlled intervention
where you monitored if
people were eating ice cream
three times a day or not at all,
you can then say that people
who ate the most ice cream,
it seemed to cause them to
be happier and healthier.
So an intervention study,
you can establish causation.
So they're really hard to do correctly.
But they're very powerful
because of their ability
to establish causation on
different nutrition issues.
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So now that we've talked
about intervention studies,
and I'm telling you they're a great way
to find out causal relationships
between a nutrient, eating
a certain dietary pattern
and a health outcome,
you might be wondering,
why don't we always do
intervention studies?
And the issue is because
many nutrition questions
are so hard to answer
through intervention studies
because of the way the
study has to be set up.
So let's think about if
you want to figure out
if eating saturated fat is going to lead
to more heart disease down the road.
Many people have tried to figure this out.
But if you want to do a
true intervention study
to try to answer this question,
you would have to
randomize into two groups.
And then you would feed a
certain level of saturated fat
to one group, maybe a lesser
level to another group.
And then you would have to
make sure that every day,
the people in those groups
are eating the correct amount
of saturated fat.
And after that, you would
have to monitor them
for like 20, 40 years,
the time it would
necessarily take to develop
a health outcome like heart disease.
And so you're gonna
have a really hard time
getting people to volunteer
to be in a dietary intervention study
where they can't eat their own food,
they have to eat the
food you've provided them
so they're eating the right
amount of saturated fat,
for 40 years.
So that's almost impossible to do,
both by getting volunteers
and having the money to do the study.
And that's why a lot of nutrition research
is not done in that kind
of intervention study way.
It's done in a more epidemiological way
to try to get the best answers we can
in a sustainable fashion.
But it's this underlying issue
to many nutrition studies
that they can't be done
in an intervention way,
and so they can't figure out
these causal relationships.
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So after we've done
whatever type of experiment
we decide to do, we're
gonna analyze the results.
In this case, all of our
experiments tended to say
that those who ate ice
cream every day were happier
and had better markers
of metabolic health.
And then we're going to accept
or reject our hypothesis.
Well, our hypothesis was
very wishful thinking,
and we thought that
people who ate ice cream
would be happier and healthier.
And in this case, we have
a confirmed hypothesis,
which leads us to the last
step of the scientific method
where we ask a new question.
So we now know that ice cream
might cause people to be,
or might be associated with people
being happier and healthier.
But I might have a new question,
like does eating vegan ice
cream have the same impact
on happiness and metabolic health
as eating dairy-based ice cream?
And then I start the
process all over again
and I analyze my questions.
That's the sixth step.
But a really important part
of the scientific method
is publishing your findings.
And so you publish your findings
in scientific journal articles.
These are the type of journal articles
that are reviewed by other scientists.
So you have to submit your
article, your findings,
to be reviewed by other
people in your field.
And then if they have feedback,
they'll give you feedback.
You'll revise the article.
And you can eventually publish it,
if it's deemed basically
worthy of publication.
As you can see, this is an
article from one of my students
who did an ice cream study,
kind of like we have talked about here
looking at people's perceptions of vegan
versus non-dairy ice cream.
And it was published in the journal
"Food Quality and Preference."
So sharing your findings
with the scientific community
and then hopefully with the greater public
is a really important part
of the scientific method.
And that is also where
some of the messages
can get really screwed up.
So if a publication goes to just summarize
your scientific findings
and then share them
on like "The Today Show" or a newspaper
or a magazine article,
sometimes they can make
the findings seem flashier
or more exciting than they actually were.
Or they'll take rat findings and say
that the same is true in humans.
So we need to be voraciously
critical consumers
of media interpretations of science,
and also even of journal
publications of science.
So you need to be a critical reader.
And I'm gonna link below to several,
to a clip from John Oliver on his show
"Last Week Tonight" where he talks about
some of the issues
involved in sketchy science
and relating science from publication
to the general public,
which is a really
important part of science.
It's how people figure out
what nutrition messages
to follow or not.
It's usually because some form of media
is telling them something about it.
Not very many people go
to a registered dietician
for their nutrition advice,
even though that would be ideal.
But we need to know how to
critically consume science
as people questing for better health.
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All right, so that's a wrap
on the scientific method.
We've talked about how scientists go about
collecting evidence to answer
burning nutrition questions.
So when you're looking for answers
to your burning nutrition questions,
make sure that you're looking at science
that has followed the steps
of the scientific method,
been reviewed by other scientists,
published in reputable journals,
and then you can apply that
information to your life.
All right, see you next time.
Click below for relevant
links and more information
on the scientific method.
Later!
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