
Too much fructose can damage your liver, just like too much alcohol - arikr
http://sugarscience.ucsf.edu/the-toxic-truth/
======
will_brown
>Scientific evidence on fructose and the liver is relatively new

People have been force feeding animals to fatten them up (gavage) for about
5,000 years, but specifically feeding them sugars/grains for the purpose of
fattening their liver.

Ever hear of the French delicacy Foie Gras(1)? It literally means fat liver,
and after 5,000 years of perfecting fattening liver what do we force feed the
animals? Corn! The same fructose we highly concentrate and load into foods and
drinks and feed to kids...which goes hand in hand, per the article, with why
kids weren’t diagnosed with fatty liver disease pre 1980’s and now 13% of US
children have it.

(1)
[https://en.m.wikipedia.org/wiki/Foie_gras](https://en.m.wikipedia.org/wiki/Foie_gras)

~~~
mrob
High fructose corn syrup is made by processing regular corn syrup (mostly
glucose) with enzymes to convert some of the glucose to fructose, making it
sweeter. Corn is not naturally high in fructose.

~~~
canttestthis
Is there a term for scientific claims made in this way? I saw something
similar on reddit the other day where a commenter was trying to prove that a
certain chemical was not harmful. It went something like "The reason we think
this chemical is harmful is because of this study from the 60s which was done
in 17 countries. But one country was excluded from the study because of
inconclusive results. Which one? The US! The country that we care the most
about, and there weren't solid results here!"

~~~
NTripleOne
I don't know if it has a term of not, but it sounds like the pretty fuckin'
opposite of science to me - adjusting the results to fit your wanted view
instead of adjusting your view to fit the results.

~~~
zero_iq
Cherry-picking / confirmation bias.

------
nnq
This is know _scientifically_ for _~10 years_ now (in a sense that there are
some studies, and the biochemistry of mechanisms is know, but the statistical
power of the studies might be low... can''t remember, left the biomedical
field years ago), and _anecdotally_ since like _for ever_ (google "making fois
gras").

Also, for cats and dogs, other sugar (xylitol if I member well) can destroy
their livers pretty fast. Fortunately, we come from sugar-happy monkeys (that
used to eat lots of rottenfruit), so we can safely enjoy our booze in
moderation :)

And for extra self-destructive power, _mix fructose and fats:_ your liver will
be too overloaded processing the fructose (that btw, also gets transformed to
extra fat and collesterol if its other metabolizing pathways get saturated) to
be able to handle the fats correctly, so "bad collesterol" will accumulate in
you blood, and then clog your arteries (yeah, it needs some extra help from
inflamation).

But, oh, wait, there's a name for that: _donuts!_ ...or virtually every other
fatty sweet stuff. Oh, and for extra-extra-damage the fats should be fried
(for reason I don't have time to detail). And there's a name for that too:
_KFC + dessert!_

 _Now go enjoy your deserts! Or the fois gras you had before it ;)_

EDIT+: video explaining some (older) science behind it, form UCTV:
[https://www.youtube.com/watch?v=dBnniua6-oM](https://www.youtube.com/watch?v=dBnniua6-oM)

~~~
KozmoNau7
Dr. Lustig's argumentation is questionable at best.

[http://www.alanaragonblog.com/2010/01/29/the-bitter-truth-
ab...](http://www.alanaragonblog.com/2010/01/29/the-bitter-truth-about-
fructose-alarmism/) [https://blogs.scientificamerican.com/brainwaves/is-sugar-
rea...](https://blogs.scientificamerican.com/brainwaves/is-sugar-really-toxic-
sifting-through-the-evidence/)

Eat less sugar? Sure! But don't do it because of Dr. Lustig's exaggerations
and paranoia. Do it because sugar is calorie-heavy with no real benefit.

~~~
birksherty
"because sugar is calorie-heavy". That's it? What about all the studies that
shows high consumption of sugar leads to diabetes, heart disease, mental
health etc.?

Who knows what is true any more? May be big sugar companies are fighting back
using fake studies and blogs to lessen the blame like they did with fat
before.

Edit: I forgot to mention 2 real examples:

1\. My father is not fat. We don't eat any junk foods, everything is cooked at
home. He goes to office by cycle, it's long commute. But eats too much sweets
and sugar, kind of addicted. He got diabetes, glucose reading 290 without
food.

2\. I started eating lots of sweets/sugar after I stayed at my parent's home
for four months. When I sleep on my stomach, I started to feel my heart beat.
It was not like this before. It was a bit scary. Then I read all those
articles about sugar, and I figured that might be the reason. I stopped eating
sugar completely. I no longer feel heart beat while sleeping on stomach. My
heart beat per minute came down from 67 to 61. I only stopped sugar,
everything else was constant.

Okay, these are only 2 cases, it proves nothing. I know. But, I don't care
what anyone says about sugar now. I know what I experienced and I believe on
that.

~~~
KozmoNau7
And what about the studies that attribute those same maladies to fat,
excessive protein intake from red meat, aluminum and countless other factors?

I know people who are fit and well within normal weight, blood pressure,
cholesterol and everything else, eat a very healthy diet and they still got
diabetes.

One of them lives almost exclusively on home-grown and home-cooked meals (they
run a small farm), he's very into working out and is one of the most fit
people I know. Yet he has type-2 diabetes.

You're absolutely right that we should all eat less sugar, but there's no
great mystery to it.

~~~
apple4ever
Those studies are starting to be shown as wrong.

I bet those people who eat "healthy" it a lot of carbs, which the body just
changes into sugar. So they really aren't eating that healthy.

~~~
KozmoNau7
So what makes you so sure the studies demonizing sugar are not equally as
flawed as the previous studies?

------
acidburnNSA
The main title in the article ("The Toxic Truth") is a tribute to UCSF's
famous Dr. Lustig of the lecture "Sugar: The Bitter Truth" [1], which is a
fascinating and well worthwhile lecture about the biochemistry of fructose as
it relates to obesity. I thought I'd just watch a few minutes of it and ended
up sitting through it and learning a whole lot.

He also wrote a book on the topic("Fat Chance: Beating the Odds Against Sugar,
Processed Food, Obesity, and Disease")[2].

[1]
[https://www.youtube.com/watch?v=dBnniua6-oM](https://www.youtube.com/watch?v=dBnniua6-oM)

[2]
[https://www.amazon.com/dp/B0095ZMPTU/](https://www.amazon.com/dp/B0095ZMPTU/)

~~~
smohare
Lustig has always stuck me as a bit alarmist. Another red flag are his
attempts to capitalize on his increase in popularity. That being said, he does
seem sincere and not attempting to spread disinformation as such.

A somewhat old, but measured take on some of Lustig’s claims:
[https://blogs.scientificamerican.com/brainwaves/is-sugar-
rea...](https://blogs.scientificamerican.com/brainwaves/is-sugar-really-toxic-
sifting-through-the-evidence/)

------
itchyouch
>That excess fructose is broken down by the liver and transformed into fat
globules (triglycerides)

I believe this is not "that" accurate. Generally the presence of excess
carbohydrates cause the body to prioritize sucrose/fructose/glucose to
glycogen conversion and storage & usage. Dietary Lipids that are ingested are
stored rather than used for energy. While, De novo lipogenesis (turning carbs
to lipids) does occur, it is inefficient enough that the body barely converts
something around 1% of carbs to fat.

Since glycogen is stored in the liver and muscles, and insulin signals the
muscles & liver to take up the glycogen in the blood, this is probably where
diabetes starts when the liver and muscles are already filled with enough
glycogen and there is no where for the glycogen in the bloodstream to go.

If the body could efficiently convert sugars to lipids, I don't think diabetes
would be that much of an issue. People would just get obese with the diabetes.

AFAIK, the priorities for energy consumption of the body is:

1\. sugars into glycogen into ATP

2\. protein into glucose into glycogen (gluconeogenesis) into ATP (some
limited amount)

3\. lipids into ketone bodies into ATP

So as long as the body was sugars to use up, that is the priority of usage.

One of the most calorically intensive tasks the body does is growth and repair
of new tissue. Excess sugars are generally used up by kids who are growing.
However, once people reach adulthood, the growth rate slows so significantly
that the excess caloric intake forces all the lipids ingested to be stored.

~~~
dl904
Something that has been popularized in certain countries is the notion that
there is a huge difference between different kinds of sugars, and that
especially fructose is harmful to people. I wonder if there is any truth to
that.

~~~
Gibbon1
What I understand is the core structure of glucose and fructose differ enough
that the metabolic pathways are different. And also while fructose tastes
sweet it isn't under homeostatic control like glucose is. So I think it's
important health-wise to distinguish the two.

There are other sugars that either differ only slightly from glucose or are
dimer, etc. AKA lactose is a disaccharide sugar composed of galactose and
glucose. Compare with sucrose which is disaccharide composed of glucose and
fructose.

------
teach
Just wanna say that my wife has a PhD in nutrition and this isn't news to us.

We've "known" that unbound fructose is hard on the liver for years.

~~~
sbenitoj
Your wife is one of the few pedigreed nutrionists who “knows” that! Sadly most
nutritionists are overweight themselves and continue to advocate people
consume whole grains, low-fat dairy, and fruit to lose weight/be healthier.
Kudos to your wife for ignoring the massive amount of BS most doctors and
nutritionists are inculcated with!

~~~
equippan
What is wrong with whole grains or fruit? I have never heard of that before.

~~~
sbenitoj
Whole grains are one of the biggest sources of dietary inflammation. There
isn’t something inherently wrong with grains, it’s that they’re not even close
to the grains we evolved to eat anymore (at least, not in the U.S. — grains in
mainland Europe are generally fine, unless you have an issue with
gluten/grains such as celiacs, Crohns, or IBS).

Source: Tons but the book Wheat Belly is one of the most succinct. Also, every
trainer who is even half-way decent at transforming clients tells them to
avoid grains, don’t discount what people are ACTUALLY doing to get results,
even if a definitive study hasn’t been done on it (although many studies have
been done, see Wheat Belly).

Fruit falls under the category of “healthy, if you’re healthy.” If you’re
overweight and inactive, and you want to lose weight, then you should not be
eating fruit, or any high-sugar, high-carb food for that matter. Once you’re
lean and physically active, it’s fine.

~~~
cheald
> every trainer who is even half-way decent at transforming clients tells them
> to avoid grains, don’t discount what people are ACTUALLY doing to get
> results

Isn't it more likely that trainers tell people to avoid wheat and corn because
they tend to be high-calorie, low-satiety foods? I've lost 70+ lbs over the
past year on IIFYM-style caloric restriction. I still enjoy corn and wheat
products, but somewhat sparingly because I'd rather have an extra half pound
of chicken than a piece of bread.

Cutting out grains is a quick and easy way to help people hack their caloric
intake more than anything else, IMO.

~~~
sbenitoj
Congrats!

Yes that’s also true. But cutting grains also fixes your sense of satiety.
Ever had a piece of bread and then next thing you knew the whole bread basket
was gone? Many people feel like they can’t control themselves when eating
bread. No one does that with steak. And even other high-carb foods like
potatoes present less of a problem for people (in terms of whether they feel
full and stop eating vs continuing to eat past the point of satiety).

IIFYM is very effective at fat loss BUT (and I know I’m going to get shit for
saying this) it requires a very specific personality type that can be very
mechanical about eating. Most people don’t have the time or interest to count
their macros, and even if they did they still have difficulty overcoming the
urges that come with consuming junk food such as modern grains in the U.S.

~~~
cheald
I don't think it's grains in particular that mess with satiety - it's
carbohydrate-heavy diets (particularly simple carbohydrates) vs protein/fats.
Protein in particular is known to be highly satisfying, _and_ it tends to be
less calorie-dense than carb-heavy foods. Carb-heavy foods are everywhere,
because they prepare easily and keep for a very long time, and provide a lot
of calories in a small package. Sugar + fat together make our brains _super_
happy and trigger the "put all of that in my face now" response. In the right
form, even starchy carbohydrates can be really easy to put down - consider a
big bowl of mashed potatoes or white rice for example!

I actually agree with you about IIFYM needing the right personality type.
[http://physiqonomics.com/fat-loss/](http://physiqonomics.com/fat-loss/) is
probably my favorite "how to be not fat" page in existence and it outlines
that issue quite well - if you can be disciplined to stop eating, then IIFYM
works great. If you can't, then full abstinence is pretty necessary. I find
that I'm much more successful on an IIFYM diet than an abstinence diet,
because on the latter I find myself craving the "forbidden fruit" and it eats
at me until I crack, then I feel guilty, and it spirals from there. On IIFYM,
I can let myself have whatever I'm craving, knowing that I just have to make
up for it with the rest of my intake that day. The actual mechanical part of
counting macros is pretty trivial once you've learned how to do it
(MyFitnessPal learns your dietary habits quickly, and trivializes the
process).

Not every approach works for everyone, but I have a lot of frustration around
a lot of the diet fads that are constantly looking for the "magic bullet" \-
no fat! no sugar! only specific carbs! lots of carbs! 3 gallons of coconut oil
daily! Only eat every 6 days! - when, IMO, the only magic bullet is self-
discipline to find out how to keep yourself from overeating, and my experience
has been that that can be different for each person based on their
psychological tendencies.

~~~
sbenitoj
Great article, just book marked it. Definitely appeals to people “like me” who
align philosophically with HN types.

My biggest issue with it, and all diet advice that wants to “give it to you
straight, it’s all about calories” is this — YES in order to lose weight you
HAVE to burn more calories than you consume, there is no question about it,
it’s tautological. But it’s kind of like saying, “in order to stay sober every
night, you have to drink alcohol slower than your liver can process.” It’s
true...but it doesn’t really answer the question you should be asking, which
is “why are you an alcoholic?” The answer to that question is more
complicated, but it’s the only question that matters.

Back to diet, when it comes to being lean — why were the vast majority of
Americans lean in the 1950s back when almost no one did any formal exercise,
especially women, and hardly anyone was counting macros, calorie counting,
etc? They just naturally ate about as many calories as their body burned off.
Their bodies had a mechanism to tell them to stop eating when they were full.
So what’s the difference between people and food 60 years ago and people and
food today? No other mammal on earth has gotten so obese as a percentage of
the population as humans have. The answer to that question, I’d argue, is the
only one that matters!

I think this is why the Paleo diet has taken off so well, because frankly we
shouldn’t have to count calories, macros, etc to stay lean — yes, those
methods work, but we should be able to simply rely on the signals our bodies
are sending us, every other lesser mammal does this, and humans did it just
fine 60 years ago.

TL;DR Yes, it’s all about eating fewer calories, BUT how you eat fewer
calories has a big effect on whether you can sustain it long term and feel
satiated.

------
lunarcave
For anyone interested in this subject - and how sugars and carbs can
_potentially_ harm your overall emotional and physical well-being and lead to
obesity - I'd recommend "Why we get fat" by Gary Taubes.

It has a surprisingly healthy dose of scientific studies condensed for the
layman, and some historical context as well.

~~~
asveikau
> sugars and carbs

I feel like carbs are unfairly vilified by a lot of people, to the point of
resembling fad diets. Anecdote: I eat very carb-heavy. I also lost 35 lbs in
the last couple of months. I didn't do it by cutting carbs.

Sugar I buy into vilifying a bit more... Since it's particularly evil how much
sugar gets added to everyday items these days, in the "high fructose corn
syrup" era which is probably responsible for a lot of the current obesity
problems. But I've come to see even a "no sugar" backlash as a little unfair.
My daughter loves sweet desserts, as kids do, and we often cave and give her
what she wants. But I've been finding on my current weight loss kick that I
can eat a lot of it with her and still lose weight every week.

For me, being mindful of portion sizes and thinking about calories
holistically has done a lot better than demonizing certain foods.

------
TazeTSchnitzel
Given the US uses HFCS a lot, whereas many other countries use other sugar, it
would be interesting to compare liver disease rates since the 1980s in the US
vs non-HFCS countries.

~~~
KozmoNau7
HFCS has roughly the same fructose:glucose ratio as table sugar, honey and
other sugars that are claimed to be less unhealthy.

HFCS alarmism is just that: Alarmism.

The problem is not the composition of HFCS, it's that we in the western world
are adding a hell of a lot more sugar to _everything_ compared to 40-50 years
ago.

~~~
nikolay
But some claim that during the conversion of corn glucose to HFCS, a lot of
contaminants end up in it, and explain some of its ill-effects to that.

~~~
KozmoNau7
Oddly enough, they don't seem able to actually back up those claims.

~~~
nikolay
Then keep on consuming HFCS. I quickly googled for the lazy you and it's not
too hard to find stuff on the subject like [0]. I am personally staying away
from all sugars except those naturally found in fruits and honey.

[0]: [http://www.washingtonpost.com/wp-
dyn/content/article/2009/01...](http://www.washingtonpost.com/wp-
dyn/content/article/2009/01/26/AR2009012601831.html)

~~~
KozmoNau7
That's production faults, not inherent to HFCS.

I try to stay away from added sugars too, but there is no reason to demonize
HFCS specifically.

~~~
nikolay
I didn't say contamination is specific to HFCS, but any large-scale low-cost
process is prone to contamination. There was another point that the fructose
part in HFCS is less stable than in table sugar, and affects the gut worse in
some ways.

------
nikolay
Fructose has always been known to be metabolized just like alcohol, so, here's
the news? The only type of fructose that's tolerable, in my view, is in
moderate consumption of whole fruits (not juice or other processed versions),
and unadulterated honey - still in moderation. When I see people eating huge
amounts of fruits, I start feeling sorry about their pancreas and liver!

~~~
kwoff
Why "unadulterated honey"?

~~~
nikolay
Supermarket-quality honey is pasteurized and has added sugar, i.e., it has
almost no benefits, but gives you all the negatives of glucose and fructose.

------
stretchwithme
Is it possible to buy processed foods that have no fructose. Certainly,
fructose is sweeter and that's why it's used so much. But would be great to
avoid it altogether. I know you can bake with dextrose.

I wish I'd taken chemistry. I see a lot of conflicting statements about
isomers of glucose.

~~~
goda90
It frustrates me when I look at things so far from "dessert" like a can of
chili, and find corn syrup or even sugar in the ingredients. Most great
homemade recipes don't use that sugar, so why should the store bought stuff?

~~~
KozmoNau7
The simple answer is that sugar is a flavor enhancer, as is salt, which is why
the level of both is generally very high in processed foods and pre-packaged
meals.

Take chicken, for instance. A lot of chicken you buy is pumped full of
sugar/salt-heavy brine, because water is cheaper than chicken. The salt helps
the chicken bind the water, and the sugar balances out the taste. The end
result is overpriced and compromised taste-wise.

Personally, I try to avoid added sugar wherever I can, and I have started
thinking of sugar as a spice to be used very sparingly, if at all. The only
exception is when I bake a cake, because cakes that aren't made full-butter,
full-sugar full-everything are just sad. Make good cakes, just eat smaller
portions of them, less often.

------
erikb
It is really, really surprising that this is discovered so lately. We should
be knowing this for 30 or so years. I have a strong guess that this article is
overpresenting how new this is. Otherwise something really weird is going on.

~~~
wutbrodo
> It is really, really surprising that this is discovered so lately. We should
> be knowing this for 30 or so years. I have a strong guess that this article
> is overpresenting how new this is. Otherwise something really weird is going
> on.

1) You're right, it's not that new. I'm pretty sure I've read it at least once
before on _HN_ itself.

2) Nutritional science is a mess not because something weird is going on but
because it's really, really hard. It's difficult enough to study the short and
long term effects of substances on the body when you're taking about a drug
but when you're trying to do it for something like food. Food is intimately
tied to culture, habit, social settings, and mood, which makes it hard to
fully regiment what your test subjects are taking. Nutrients also both appear
and are metabolized in extremely complex arrangements that we still don't
fully understand (even something as basic as calorie counts use a pretty
ridiculous, roundabout measurement technique), which makes it hard to
accurately track. It also is something that everyone has to do all the time,
so (unlike drugs), we have to go with "best current understanding"
recommendations, which create their own political and reputational effects on
scientific study when they're contradicted.

We just this year upended decades of public health consensus on the effects of
low sodium on blood pressure. This isn't "something weird" going on, it's par
for the course for the field.

~~~
erikb
Okay, thinking about your arguments I have to agree. This is not about
nutritional advise but about nutritional science. In the pure science
department having a good enough result to statistically trust it is rare and
may happen even two or three generations until it is common believe already.
It is actually good that they ignore common believe in favor of reliable data.
Someone must.

------
manigandham
Based on how much conflicting studies, stories, evidence, research and
anecdotes out there, it seems nutrition is the one thing that really just
boils down to self-experimentation, moderation, and common sense.

------
cies
Without saying how much is too much :)

I wanted to know because it is probably really hard to reach without
processing the sugar. IIRC dates are most fructose dense food we can find in
nature. How many dates would be enough to damage my liver?

It would probably be hard to hurt your liver with alsohol as well, if you
limit yourself to unprocessed alcohol (i.e.: by eating off fruits).

~~~
arikr
I've read Lustig's book, and my recollection is that he says that more than
10% of your daily calories from (all, both added sugar and naturally included
sugar, if I remember correctly) sugar is too much. So if you're eating 2000
calories/day, then 200 calories from sugar, which means 200/4 = 50 grams total
(including added sugar).

Separately, on the sugar science website they say:

> our scientific team recommends keeping all __added __sugars below the
> recommended limits of 6 teaspoons /day (25g) for women and 9 teaspoons (38g)
> for men.

[http://sugarscience.ucsf.edu/sugar-
faq.html](http://sugarscience.ucsf.edu/sugar-faq.html)

~~~
runeks
So one orange, a large apple and a banana per day will hurt my liver (totaling
63 grams of sugar[1])?

Where is the scientific evidence supporting this?

[1]
[http://www.sugarstacks.com/fruits.htm](http://www.sugarstacks.com/fruits.htm)

~~~
kieranmaine
I just watched a documentary where Lustig said sugar in fruit is fine because
the fibre in the fruit means you absorb the sugar over a period of time,
meaning the liver doesn't get one big hit.

~~~
siquick
No citation available, but I see far more people drinking fruit juice than I
do eating fruit with the skin/fibre still intact.

~~~
woodandsteel
Fruit juice is no better than soda pop.

~~~
brewdad
At least fruit juice has some nutritional value. You're right though that it
still isn't a "healthy" choice.

------
stretchwithme
I hear as bananas ripen, the sucrose breaks down and more fructose is
available. That's why they get sweeter. So healthier not to wait too long.

~~~
jlg23
It's been a long time I did biology in high school, but a quick fact checking
on WP suggests I'm not too far off: This is true for most/all(?) fruit and yet
untrue for humans because sucrose is broken down into glucose and fructose by
the body anyway.

------
jlebrech
going to bed with left over sugar is bad for you. but for regular exercise
sugar is good too (slower carbs are better)

It's all about balance, possibly everyone should have a blood glucose meter
and burn off that excess glucose every night.

------
eighthnate
Doesn't too much of anything damage your body?

------
guessmyname
Too much of everything is always bad.

~~~
amasad
>Too much of everything is always bad.

That's folk-wisdom, which is sort of a good heuristic but is not useful when
we can actually test and demonstrate. Some things are bad even in small
quantities, say poison. Somethings we can't get enough of, say fresh air.

I've mostly cut out fructose (and most other forms of sugar) altogether from
my diet and it's probably the single-most impactful change that I've made in
my lifestyle on my well being.

~~~
guessmyname
> Somethings we can't get enough of, say fresh air.

Well, if you get too much air, the pressure will probably kill you, so...
¯\\_(ツ)_/¯

~~~
yjftsjthsd-h
I would have gone with hyperventilation, though there's a cutoff there

------
swendoog
Why is it that I can eat tons of sugar, including HFCS soda, and not gain any
fat?

~~~
Mz
I don't know the answer to your question about you in specific, but I have a
genetic disorder that predisposes people to being super thin. One element of
it is that fats are misprocessed.

I have made some headway on dealing with it. But, I mean, I wouldn't know
where to begin to explain it and I have no idea how it relates to your
experience. So, I mean, I don't know what pieces to even talk about. If I know
someone has, for example, diabetes, I can come up with pertinent things to
say, even though that isn't my condition.

There is a lot of info out there these days. You may be able to eventually
hack this and find a means to put on weight.

------
enraged_camel
It's almost as if too much of any one thing is bad for you.

It's interesting that science is _just_ figuring this out. And I say this as
someone who has doctor parents.

