new study just came out this week looking at erythritol, which is a substance used
as sweetener, as replacement for sugar in some products. the study seems to suggest
an association of cardiovascular disease with erythritol, so the media had a field day with
this. CNN, ABC News, the New York Times, People magazine, they were all over it. and predictably,
there was a huge hoopla on social media, people panicking over it
etc. some people even called it erythritol-gate. okay, that was just me. and several scientists
went on social media, they tried to put out the fires and explain the caveats, the problems with
the interpretation of the study etc. so let's take a look at the study, what it found and what it
means for us. the main finding was that the blood level of erythritol correlated with cardiovascular
events. so events means heart attacks and strokes. so the people with the highest level of
erythritol in their blood had the most heart attacks or strokes. the main problem with that,
as several scientists explained on social media, is that erythritol is produced endogenously, our
body produces it. the study even mentions this: erythritol is endogenously produced. so measuring
blood levels of erythritol doesn't necessarily tell us much about the effect of eating it.
people who have higher levels might just produce more, not necessarily eat more.
they might not eat ANY erythritol, potentially. so that's the main limitation of the study,
we have no idea how much, if any, erythritol these people were eating, were actually eating, because
that just wasn't measured. the study even explains that in one of their data sets, the measurements
were made before erythritol started being widely used as a sweetener in processed foods,
so at least in that group, the measurement is unlikely to reflect intake. so there's
a massive logical leap between what the public perceives when they read these media pieces or
when they saw the pieces on CNN and all that and what the study actually measured. now,
smart viewers might say, okay, so this study doesn't really tell us if those participants
were actually eating erythritol, but if high blood levels were linked to disease,
maybe we should just eat less of it to keep our blood levels low, right? that's a reasonable
thought process, but here's the second problem: the erythritol production in our body responds
to all kinds of disturbances. erythritol levels go up in pre-diabetes, in diabetes,
as a response to osmotic stress, they may respond to dietary glucose and fructose, oxidative stress
etc etc. so the fact that people who have higher blood levels of erythritol tend to be sicker
doesn't tell us if it's erythritol itself causing the problem or if it's just a marker of disease
or of an unhealthy diet with a lot of refined carbohydrates or a number of other things. and
if that's the case, if it's just a marker, then changing dietary levels might not do anything, we
really can't tell from this type of measurement. in fact, in the study they split the participants
into four groups based on their blood level of erythritol, group one had the lowest level. groups
two and three had more but their cardiovascular risk wasn't significantly higher than group one.
only group four, which had the highest erythritol blood levels, had significantly higher risk,
but group 4 also had about three times more people with diabetes than group one,
so again it might just be that they're sicker to begin with and their erythritol level reflects
that, it's a marker of sickness rather than erythritol itself causing heart attacks. now,
researchers aren't dumb so they see these differences in diabetes in their data sets
and they try to minimize confounders as best they can. so they adjusted statistically for diabetes,
blood pressure, a few other factors, and the effect size came down substantially, was reduced,
which suggests that indeed a chunk of the original effect was due to these differences in sickness.
there was still a significant effect left, but it could easily be explained by some of these
other factors that also affect endogenous erythritol production, like pre-diabetes,
a bad diet, different types of stress that were not included in the adjustment models. so the
main weakness of the study, and it's hard to get around it, is they're primarily looking
at a marker of disease in the blood and not necessarily at the effect of consuming, of eating
erythritol. and actually, it was already known that people with higher blood levels of erythritol
tend to have higher risk of coronary heart disease, this has been published in the literature
for at least four years, and even this discussion of "is the blood level of erythritol a marker of
disease or does it actually cause anything?", that's also published in the literature, none
of this is quite brand new. so what the authors tried to do in the second part of the paper is
they tried to bolster those human data by testing the effect of erythritol on some lab models. and
they found that erythritol seems to promote blood clotting both in vitro, so in a test tube assay,
and also in a mouse model. and the last thing they did was they got a group of eight people
and they fed them some erythritol and looked at their blood levels and they confirmed that they
indeed shot up very high and stayed pretty high for a couple days. so the results in the test
tube and in the mice raise the possibility that eating erythritol might induce blood clotting.
is that also going to be the case in humans? is it going to affect cardiovascular risk? in which
direction? what's the net effect of intake of erythritol on cardiovascular disease? all TBD, all
unclear at this point. we have to be very careful with this type of lab data, in test tubes and in
mice, what we call mechanistic data, because it's very common for it not to reproduce in humans,
and even when it does, it's not uncommon for the same molecule to have other effects and
for the net effect of the food or the treatment in a living breathing human to be unpredictable
from these lab tests in isolation. for example, there are published results, also in vitro,
in test tubes or in lab animal models, pointing to benefits of erythritol. like for example reduced
weight gain, antioxidant activity, vasoprotective effects on the endothelium and lower glucose
levels in rodent models of diabetes. so which one do we go with? the mouse result pointing to
harm or the mouse result pointing to benefit? right? this is why scientific positions on the
likely health effect of a food or treatment have to hinge on human data, what we call outcome data,
because if you run enough assays in a test tube or in a mouse in a laboratory
you often find results going in several different directions. and the truth is, the central human
data in this paper, that association between blood levels of erythritol and cardiovascular risk,
is not fundamentally new and it's very inconclusive. now, according to the trial
registration, which is something that scientists are supposed to do before they start a trial,
you're supposed to submit a description of what you're going to do,
and according to that they also tested the clotting effect in their human subjects,
but that data didn't end up in the paper, it wasn't published. I'm not going to speculate
on why but if they publish it at a later date that could add a bit more
information. so there is some uncertainty with these products, especially long-term,
consuming them for decades at a very high dose, we don't really know everything that happens, and
it's good to acknowledge areas of uncertainty but we should avoid jumping to conclusions and making
these categorical claims that are not backed by evidence. there was basically a stampede on social
media, people essentially pulling their hair out, even people with some scientific training,
some medical doctors making just bizarre claims. I saw some people, not going to name names but I saw
some people saying this proves cause and effect between eating erythritol and cardiovascular
disease. the intake of erythritol wasn't even assayed, wasn't even measured in the population
where cardiovascular risk was reported. others telling all their followers to drop
everything with erythritol because this study proves that it causes cardiovascular disease.
I even saw people say that we don't need any more research, we don't need trials, this settles it,
eating erythritol causes heart attacks, case closed. that's completely divorced
from scientific reality. at a broader scale, I've noticed a pattern on social media with these waves
where people will basically decide that a food is terrible for you with little to no scientific
evidence to back it up and then just repeat it on loop until everybody's very emotional
and very angry about it and especially upset if something is questioned or if evidence is shown
to the contrary. and then sometime goes by and the wave dies down and it moves on to another
food. but the whole time the scientific evidence on that food that was focused on during the wave
barely changed. I saw this with lectins five years ago, I've seen it with different types of oils and
now it seems to be about these artificial or alternative sweeteners. it's fashionable to
say that they're bad for you, with or without the evidence, right? everybody on Instagram and Tik
Tok is repeating the same thing and a year or two from now it's going to be another food. I don't
have a dog in this fight, don't really care about these sweeteners one way or the other,
more than happy to come on and tell people to dump them if and when the science points to it,
but most of this mobbing and this repetition that I see on social media
does not reflect the current science. we can and we should acknowledge areas of uncertainty
without the wild overclaims. take this study for example, it's compatible with pretty much any
scenario. it's compatible with erythritol being harmful. it's compatible with it being harmless.
if the blood levels are just a marker of disease that explains the association, and the mouse data
might not pan out in humans. it's even compatible with benefit of erythritol. for example,
there are some small pilot trials where they took some diabetic people and they gave them
erythritol and several of their cardiometabolic markers improved. their glucose levels came down,
their hemoglobin A1c, and blood pressure, those that had the highest blood pressure, that came
down as well. so we could hypothesize benefit of eating erythritol based on the available evidence
and it wouldn't be unreasonable. as a hypothesis, not as a claim, right? so the next time you see
the scary headlines with people losing it on social media, bear in mind we have to look at all
of the available evidence on a topic, not just the study that just came out this week. it's pretty
rare that an individual study flips a field, it's much more common that people just overreact. some
studies that could actually push this forward a lot: randomized trials, especially long term,
that'd be great. good cohort studies measuring actual intake of the sweetener, not just blood
levels which is harder to interpret, especially for a molecule that's produced endogenously.
and genetic studies, mendelian randomization, could be interesting as well. in the meantime,
what do we do in real life? for people who have pretty healthy diets with not a lot of
added sugars or processed foods or sweeteners, no reason to add them. that's kind of obvious.
but then again, that's not the target audience. these products are designed
to replace regular old school sugar added to drinks or sodas or in processed foods,
and the existing evidence is pretty compelling that they outperform regular sugar or
sugar-sweetened drinks when it comes to weight maintenance and metabolism. so I would recommend
a diet soda over a regular soda easily for people who are going to have one of them anyway.
and in the long run, until we know more, if you want to gradually phase out the sodas and the
processed foods altogether, that's probably a safer bet, and not just because of sweeteners.
several viewers have told me they prefer stevia, sometimes it's perceived as being more natural,
whether it really is or not is debatable but yeah I don't see a problem with picking that
over another option. there will probably be studies in the future that will fundamentally
change our confidence in sweeteners one way or the other, towards safety or harm, but in my
opinion the study that just came out doesn't do that, it doesn't really change much. here's our
previous video on sweeteners for more detail, I hope that all helps, I'll see you guys soon