The folks that used artificial
sweeteners the most in this study had
the most cognitive decline. How could
sweeteners cause cognitive decline if
that really is what's going on? So, we
have finally have a study maybe by
chance that shows artificial sweeteners
are doing bad things. But hold on a
second. How artificial sweeteners might
affect health is not the same thing as
strong evidence that they do affect
health. So, should you stop consuming
artificial sweeteners?
Hey folks, Dr. Dr. Mike here for RP
Strength and I have a question for you.
Are artificial sweeteners making you
dumber?
They sure made me know. I was dumb
before.
So many of us consume artificial
sweeteners
and most of us assume that they are
healthy.
And for body health, this is very well
vetted. But what about brain health? Are
we destroying our brains with these
chemicals? Tonight, news at 11. Why are
we talking about this? A massive study
just came out. Gunglavus at all. The
study title is association between
consumption of low and no calorie
artificial sweeteners and cognitive
decline. An 8-year prospective study in
the journal of neurology. You don't just
publish BS in that journal. Published in
2025. It's very, very recent.
8 years.
12,000 people included in the study.
The folks that used artificial
sweeteners the most in this study had
the most cognitive decline. The
sweeteners examined included aspartame
or uh Scott as one of my friends
acquaintances said aspartammy.
>> Oh, that's nice.
>> It's fine.
Saccharine,
asylum K. Esulfane, potassium,
arythritol, xylitol, sorbital, and
tagos, which I've never heard of, but
sounds fun. The paper reported
associations for most of these with
cognitive decline, except for tagatose,
which just go out and buy tags stock.
Don't do that yet. Don't do that yet.
Hold up.
So, is the cause established? Is it
artificial sweeteners in this study
cause cognitive decline? The answer is
no. This study design cannot establish
cause and effect. It can only establish
correlations, aka associations, because
no variables were purposefully altered
and others maintained the same for us to
be able to infer cause and effect.
A while back, another study found that
artificial sweetener consumption was
correlated with higher body weights,
which led some people to conclude that
artificial sweeteners actually cause
body weight gain. And the naturalistic
fallacy folks just like this was the
greatest thing that ever happened. They
were like, "See, told you see." But it
turns out every time we ran an
experimental study where we gave one
group artificial sweeteners and the
other group not giving them artificial
sweeteners, the artificial sweeteners
group lost just as much weight,
sometimes more weight than the group
that wasn't given them. And so it turned
out that it was just correlationary. And
the reason it was correlated is
correlated. The reason it was correlated
is because when you look at populations
size cohorts, guess who does more diet
products? People trying to lose weight.
Guess who's trying to lose weight? Fat
people. So when you look at who uses
artificial sweeteners more, it's fatter
people use them more because skinny
people don't give a.
So it was backwards. A great example
when you think a study shows something,
but it's actually backwards. But it
makes you think maybe there's a cause
here. So, how could sweeteners cause
cognitive decline if that really is
what's going on? First, the gut microbe
and brain axis. This is probably the
strongest idea for a shared pathway.
Sweeteners have been demonstrated to
alter gut bacteria and gut bacteria and
brain signaling pathways.
This is definitely a thing. It doesn't
prove anything, but gut bacteria could
be a mechanism.
Another one was metabolic dysregulation.
If a sweetener worsens glucose control
or insulin signaling in some people, it
could hurt brain health indirectly.
But um this one's tough because most
sweeteners just don't affect in humans
glycemic control whatsoever. In animals,
they can sometimes do that, but not in
humans. Okay. Another one that was
interesting to me is inflammation,
specifically neural inflammation.
This comes up mostly, but not only with
aspartame, which uh it does have some
studies linking sweeteners to oxidative
stress, inflammation, mitochondrial
problems, and even neurotransmitter
changes. For aspartame, the suspected
issue is often its breakdown products.
But the direct research on here hasn't
been super supportive.
And for erythrtol and xylitol uh and
other sugar alcohols, it may be a
cerebrovascular and endothelial
situation because some studies found
that more platelet activity and clotting
potential was a thing after the intake
of these artificial sweeteners and
arythril may also uh impair tiny blood
vessels in the brain from operating
properly over time that could plausibly
affect cognition. And that sounds
really, really bad, but hold on a second
because other things may be going on and
almost certainly are. First, there's a
phenomenon in science called the file
drawer effect. A large fraction of the
file drawer effect looks like this.
Scientists do all kinds of studies. Some
of them show the kinds of effects that
would be like really worthy to publish,
like stuff happened. But then other
studies will be conducted and sometimes
you conduct a study to test like eight
or nine different things. You can
publish a bunch of papers off of that
study. But some of the variables just
don't change like there's no effect. And
you typically don't on average people
don't like to publish papers that say
nothing changed, nothing happened. And
so if you have a study, a meta study
that's done that studies 10 variable
changes and only three variables change,
you might get papers uh you know, one
paper each on each one of the three
things that changed. You might get a
synthesis paper for the three things
that changed and they might say, "Hey,
by the way, these are the things didn't
change." But you're not going to get an
independent paper on each one of those
things that didn't change. This is a
very well doumented phenomenon. It
happens all the time. It's happening
less and less slowly, but it's still a
big problem.
To that end, there are oodles and oodles
of studies
which uh have this file drawer effect
phenomenon. And it ends up being that
what is really going on, we don't see
because we're only fronting what is
interesting. It's like a social media.
People post their best pictures and you
think everyone looks like that all the
time, but that's not true. And so
there's probably a lot of research where
they couldn't show artificial sweeteners
doing diddly dick and it just never got
published because it's not interesting
to anyone. And so we have finally have a
study maybe by chance that shows
artificial uh sweeteners are doing bad
things that get gets published instantly
because holy shit that's big news.
There is another situation where you
say, "Okay, it's dispiosis, it's
inflammation, right?" It turns out there
are loads of studies that show that
proteins, carbs, fats, and damn near
everything else in some instances will
cause dispiosis and inflammation. And
so, man, if that many things cause
dispiosis and and metabolic
disregulation and inflammation in a
bunch of different studies, like how
does that make artificial sweeteners
unique? And by the way, they don't cause
all these things in the vast majority of
studies, just in some studies here and
there, which is why all those other
mechanisms I listed were just plausible
mechanisms, not likely mechanisms.
The other thing is this. If you measure
enough endpoints in cells, rodents,
stool samples, cytoines, metabolites,
receptors, and gene expression panels,
you can make almost any exposure look
really gnarly. Animal research reviews
specifically flag selective analysis,
biased outcome reporting, and
publication bias as reasons effects get
chronically overstated from testing
anything and seeing how it affects
anything else. So yes, gut bacteria
changed or oxidative stress marker moved
or inflammatory pathway twitched is
often a hypothesis generator like oh
this is a cool idea let's study it more
rather than hey this thing for sure is
caused by this.
The mechanisms of how artificial
sweeteners might affect health is not
the same thing as strong evidence that
they do affect health.
Here's the real kicker. There's a few
other ones that are even bigger deals
for why we should be looking at the
study with a bit of reservation.
Directly from this study, the folks in
the study who used more artificial
sweeteners and thus had more cognitive
decline also statistically had more of a
chance of the following things. This
one's going to kill you guys uh quite
literally if you had these. Being
diabetic, having a higher body mass
index and more body fat, having higher
blood pressure, having a higher
incidence of diabetes, which leads to
cognitive decline, by the way, had a
higher consumption of ultrarocessed
snack foods
and more alcohol use. But Scott, we know
alcohol use doesn't cause cognitive
decline. Of course,
>> it's not literally brain poison. No big
deal. Also,
more of these people than not were shown
to be actively dieting to try to improve
their health, which is another way of
saying that they were assessed
themselves to be in poor health to begin
with. It's weird that people who are in
poor health at the beginning of an
8-year long study have cognitive decline
through the the remainder of the study
because most of them won't be successful
improving their health because most
people are not successful in improving
their health because they don't stick to
diets or workout regimens. Strange how
that works. This screams reverse
causality like the older weight gain
studies with artificial sweeteners where
it was just the fat people using them so
it looked like they made people fat. Now
it's the people in really really poor
health using them and it's like surprise
they have one of the downstream
consequences of poor health which is a
degeneration of neural function.
The World Health Organization explicitly
cautioned that evidence linking
non-sugar sweeteners to bad long-term
outcomes may be confounded by baseline
participant characteristics and complex
pattern of use. The UKSACN
went even more bluntly about this and
said that observational studies of
sweeteners are highly vulnerable to
reverse causality, the same thing we've
been talking about,
and residual confounding, other factors
being responsible because people may
choose sweetened diet products because
they are overweight or at metabolic risk
rather than the products creating the
problem. Scott, we can have a good study
that shows pe that casts break people's
legs.
>> Yeah. Yeah, it sounds good.
>> I mean, everyone I've ever seen with a
cast had a broken leg. I'm starting to
think, "Hey, Mr. Cast, where were you on
the night of the 15th?" Like, "I swear
to God, it wasn't even real yet." That
sounds like makebelieve bullshit to me,
Scott. And then, Mr. Cast, the police
don't like put him in in jail, they just
beat the shit out of him.
>> Jesus.
>> Brutally. Oh god. Oh my god. You don't
break the cast, the whole thing.
Here's the real shit. Association
studies are hypothesis generating. get
ideas and then we actually study them in
randomized control trials where we
manipulate very carefully certain
variables to see how it affects others
so we can get a direct cause and effect
understanding.
So you may ask yourself the question of
what what do those studies say about
artificial sweeteners and health?
Well, here's some sampling. A 2025 meta
analysis of nine randomized control
trials comparing artificially sweetened
beverages with unsweetened beverages
found no significant differences in
weight, waist circumference, fasting
glucose, H1 uh HBA1C or glycloated
hemoglobin. It's an index of how
diabetic you are, insulin resistance,
lipid profiles, or blood pressure. Okay,
so all all of these inflammatory and gut
disbiotic and metabolic disregulatory
mechanisms that are imbued on these
sweeteners should be doing something and
they're absent when you actually look at
direct cause and effect analysis.
An earlier 2022 review, systematic
review and meta analysis for 17
randomized control trials found that
using low or no calorie sweetened
beverages instead of sugar sweetened
beverages improved body weight and some
cardiumabolic risk factors along with
that without any evidence of harm.
That's a big deal.
There is also a one-yearong trial. I
love the acronyms for this are amazing.
It's called the sweet trial. S wet t.
It's a randomized trial and it found
slightly better weight loss and
maintenance with sweeteners and
sweetness enhancers than without and no
worsening of cardioabolic risk markers.
Even though in those studies gut
microbiota changed. So the gut
microbiomes changed and didn't affect
seemingly any other part of their health
spectrum. And they actually had more
success using artificial sweeteners than
not using them over the course of a
year. you would think you would pick up
something.
And a reminder here is that randomized
control trials are a category level
stronger of evidence than cohort
association studies like this 8-year
long 12,000 participant study was. So if
we're looking at the best kind of direct
research, it shows that there's no
reason to suspect that artificial
sweeteners cause cognitive decline. And
we already know diabetes, higher BMI,
and all that other stuff those folks
have absolutely do cause cognitive
decline, never mind the alcohol
consumption. So, should you stop
consuming artificial sweeteners?
I assess that the probability that
artificial sweeteners, especially from
so many different classes, because
they're very, very different kinds of
drugs,
cause cognitive decline is very low. And
that's just because I'm scared to have
cognitive decline. I eat a ton of
sweeteners. Case closed. Just kidding.
The probability that excess calories
from sugar that lead to obesity cause
cognitive decline is almost 100%. Like,
we know this for a fact.
Now, this study might be on to a real
cause. And so, consuming measured
amounts of artificial sweeteners may be
better than consuming infinite unlimited
amounts for folks that read this and are
a little bit put off, a little bit more
riskaverse.
But consuming less of the super
unhealthy ultrarocessed snack foods is
probably the real insight. If anything,
if artificial sweeteners for you help
with sweetness cravings and allow you to
consume fewer calories because of it and
hit your diet goals, keeping weight in
the healthy range, this is a huge deal
and almost certainly overpowers any of
the other kind of effects these
substances might have negatively on your
health. And again, it's by no means
clear they do. And all of the direct
studies say they probably don't.
Metabolic syndrome and its associations
of diabetes and obesity it are proven
causes of cognitive decline
straight up. And so we already know
where to work there. My best
recommendation for this reason is to
stay the course and continue to use
artificial sweeteners if you like as
much as you like. That does not mean
artificial sweeteners are free from
criticism and guaranteed to be safe
forever. But we need way better studies
to cancel out all the studies that say
they're totally fine and put up a huge
volume of aggregate evidence to say,
"Okay, now we know they're bad for
sure." It's probably never going to
happen, but if it does, it's going to be
more than one study here and there. Sure
shit going to be more than one
association study. And a sure shit going
to be more than one association study
that found that the people who have
these problems are also more likely to
be diabetic, more likely to have
metabolic syndrome, and more likely to
be high consumers of ultrarocessed foods
and alcohol for the love of God. So for
the time being, our best as far as I can
speak for the scientific community, my
best, let me take that back.
Understanding seems to be that
artificial artificial readers are
probably neutral for health, plain and
simple. If they help you achieve your
goals and have some fun along the way, I
think they're totally great. This video
was brought to you by Big Artificial
Sweetener. It's literally one guy. He's
huge. He comes to your house and he's
just like, "You better say the right
shit." Yes, sir. So, I typed up this
this up. I'm scared. This is a cry for
help. I'll see you guys next time.