Chronic alcohol exposure stimulates adipose tissue lipolysis in mice: role of reverse triglyceride transport in the pathogenesis of alcoholic steatosis
This is how you really examine frozen liver samples for steatosis in a real laboratory:
"Neutral lipids in the liver were detected by Oil Red O stain. Liver cryostat sections were cut at 7 μm, fixed with 10% formalin for 5 minutes, and stained with Oil Red O in 2-propynal solution for 10 minutes"
The image on the right (for Ed to enjoy, even if the approach is a little basic compared to what you can do) is from one of the alcoholic mice, lots of lovely lipid accumulation:
And if you want to know about hepatocellular damage, you measure leaked ALT in real plasma from real blood:
"... the plasma ALT level was significantly higher in alcohol-fed mice (68.8 ± 17.0 U/L) than pair-fed mice (28.4 ± 6.7 U/L)".
No suggestion of homogenising liver and measuring ALT in the supernatant!
OK, so these folks seem quite honest and to know what they are doing. That's very nice.
What did they actually do? They deuterated the fatty acids in the adipocytes of live mice, got half of the mice drunk for a few weeks and then measured how much of the deuterated triglycerides turned up in the liver.
Lots did.
They also checked out why the adipocytes released their FFAs under ethanol. The mice developed whole body insulin resistance and they particularly developed adipocyte insulin resistance. If your adipocytes resist insulin, you get thin. Vodka makes you slim, while it grossly fattens your liver and makes you (mildly) insulin resistant.
As they say in the paper:
"In conclusion, the present study demonstrated that reduction of WAT mass and adipocyte size was associated with alcoholic steatosis. Activation of ATGL and HSL due to adipose insulin resistance is likely the major cause in alcohol-induced WAT reduction"
Speculation: Combining alcohol with a carbohydrate load (Beer!) will still make you "sort-of" slim, because any lipid you manage to force in to your adipocytes, using the hyperinsulinaemia needed to achieve normoglycaemia, will be released as soon as insulin starts to fall and you end up with a central beer belly combined with skinny arms and legs peripherally... Back to the paper.
The core slimming effect of ethanol is based on the induction of insulin resistance within adipocytes... This releases FFAs and the FFAs, if not utilised, are stored in liver and visceral adipose tissue.
You really have to wonder how much of the hepatic steatosis of fructose is generated in the same manner as that of alcohol, primarily driven by reverse transport of FFAs from adipocytes to hepatic cells. It would also be interesting to know if PUFA were released from adipocytes alongside the fructose-generated palmitate we talked about in the last post. The adipocytes certainly release multiple PUFA derived FFAs for transport back to the liver under the influence of ethanol.
Peter
BTW, did anyone notice that this group, who appear to be good, didn't measure or report plasma FFAs? I'm guessing FFAs are not markedly elevated in alcoholic reverse lipid flow, so trying to work out what is happening to lipid transport (or oxidation, for that matter) from FFA levels might be somewhat fraught, in any of those studies in which FFA levels are reported in the absence of isotopic tracking... Makes things tricky when you go on to think about fructose studies.
Very interesting! Trying to imagine tipsy mice. Couple of thoughts:
ReplyDelete1. How much did they have when scaled to humans? Could probably do the math myself but I guess you already have?
2. Again something Rob Lustig did not mention in his Fructose 1.0 lecture! He made it sound like fatty liver is entirely due to palmitate and similar manufactured in the liver from ethanol or fructose.
3. The famous beer belly (small hard paunch with spindly extremities as opposed to generally large and soft) cannot be entirely down to fatty liver or else it would be asymmetrical, so the beer belly seems to form because visceral fat is favored over subcutaenous. The paper does not say why subcutaneous apodicites are different from visceral. Why would booze + starch drive fat out of the extremities and into liver + visceral apodicites?
4. My impression was that there is a sort of consensus (not aware of studies) that carbs in general and especially under metabolic syndrome will favor visceral, while overeating on low sugar, maybe slightly low carb food will make one large but favor fat everywhere in the frame. If this is correct, again, why the difference between belly and extremities?
5. Why does the liver accumulate FFA in the first place? Is it trying to maintain limited serum FFA? Are there other condititions that would result in release of plenty of FFA? Is this why TPN avoids fats with the exception of EFA?
Puzzled
Eric
Eric, my feeling is that ethanol simply empties adipocytes and the lipids have to go somewhere. The liver is the main clearing house and quite why the resulting VLDLs target visceral adipocytes is an interesting question. But yes, a beer belly is largely visceral fat, probably in addition to an enlarged liver.
ReplyDeleteAll I can say is that in the current ethanol study plenty of deuterated PUFA showed up in the alcoholic liver, having originated in the peripheral adipocytes (presumably getting to this site via chylomicrons from the gut).
No one generates PUFA from alcohol or fructose yet I thought this sort of stuff https://www.ncbi.nlm.nih.gov/pubmed/26405460 was common knowledge. There are also some nice Oil red O stains from a corn oil based diet in https://www.ncbi.nlm.nih.gov/pubmed/21162572 (though quite how relevant to anything over-feeding a diet with 70% of calories from corn oil is, I'm not so sure). Nice pics though!
Yes, I would suspect there is some sort of monitoring of FFAs, more likely in the brain (plenty of CD36 in selected brain areas) than the liver per se, but you never know and the vagus nerve is plenty long enough to let the brain talk to the liver.
Peter
Eric,
ReplyDelete"4. My impression was that there is a sort of consensus (not aware of studies) that carbs in general and especially under metabolic syndrome will favor visceral, while overeating on low sugar, maybe slightly low carb food will make one large but favor fat everywhere in the frame."
I thought it was the other way round, eating low carb is good for losing subcutaneous fat, but only reduces visceral fat if you are eating low enough calories. If eating too much fat I think you tend to add visceral fat as "temporary" storage but it never gets used so just accumulates. Some bloggers use this idea to advocate "nutrient partitioning" where you eat more carbs on high calorie days hoping they go into muscle and whole-body fat (sumo wrestlers!), and eat low carb on low calorie days to lose fat all over (don't think the sumo guys bother with this bit :-).
Hold on, you lost me there, Peter. The peripheral adipocytes release FFA which travel to the gut where they hop onto the VLDL bus to take the portal vein to the liver? Isn't it more likely they get there as FFA in the general circulation? Or can they hitchhike the VLDLs just about anywhere?
ReplyDeleteWhile I didn't know the paper, the general idea was not news to me. However, one should never assume too much literacy: https://tim.blog/2009/10/05/gout/ Apparently, Walt Willett and his gang were until recently blissfully ignorant that sucrose is half fructose *gasp*
Malcolm: Not sure where I picket up that idea. However, folks in Europe tend towards the beer belly physique, whereas in America, if they are obese, the tend to be LARGE and flabby everywhere. The most striking difference is that the SAD still contains a tad more sugar.
Adipocytes release FFAs in excess of metabolic needs, liver mops them up, re packages them as VLDLs, secretes them, they are addressed to visceral fat (how? I'm thinking about that)
ReplyDeletePeter
Yes, no argument about this concise summary. I just was puzzled about the previously proposed detour to the gut. Is that real?
ReplyDeleteThanks
Eric
Ah, see what you mean. PUFA have to come initially from the gut. They would get to the adipocytes via chylomicons. Then lipolysis can divert them to the liver. Of course some PUFA will have travelled directly to the liver, also via chylomicrons. Trying to tease out the relative importance of adipocyte derived PUFA in the liver is a lot of what I'm following at the moment. Not clear cut!
ReplyDeletePeter
walking past pubs in a London all i'll think of is 'beer belly combined with skinny arms and legs'
ReplyDeleteHey Peter,
ReplyDeleteSo I've been operating on the optimal diet for a little while now, and although it has been essentially kind to me I am having two issues - which by no means require thorough scientific analysis but as you have much more experience operating under the diet I am curious as to your interactions with said issues. The first is bowel movements and texture being essentially unpleasant. I am defecating often and it trends towards a more liquid format. As there is a general discouragement of fiber that serves bacteria and not the human I am curious how you solve for this issue, or if you essentially tolerate it. The second issue is energy levels - my body is seeming to struggle with my energy feeling low & having the compulsion to nap regularly. Now I've raised my sodium, potassium, and magnesium intake to curb this, as well as upped my caffeine intake, but the fatigue still prevails. I am curious if you experienced this in your transition or if this is an abnormality I'm experiencing.
I apologize for this comment not relating to your post.
Hi Jay,
ReplyDeleteAs I'm not a clinician, the number of people I know who have had problems on VLC eating is low and there may be all sorts of things going specific to yourself. If you have some sort of specific problem with fat absorption it would give steatorrhea and be a functional low fat diet. Low fat/low carb would undoubtedly give low energy. I've also heard of SSRIs being associated with diarrhoea on VLC diets too. Just some thoughts...
Peter
Hi Peter. The predominance of PUFA is a mystery, but the rest seems to make sense. The body treats alcohol as a toxin, prioritizing it for energy use. This requires physiological peripheral insulin resistance, as well as visceral body fat uptake, to prevent other sources of energy (including stored fat) from being used. Visceral fat is very easy to mobilize, much more so than subcutaneous fat. So it is next in line as blood ethanol levels go down, as long as calorie intake is limited to, or below, energy needs. In my view, transitory visceral fat accumulation is not, in itself, a problem. Calorie intake regularly surpassing energy needs definitely is, because visceral fat accumulation becomes non-transitory.
ReplyDeleteJay, I do 14-10 intermittent fasting, lowish carb, high fat (butter, cheese, olive oil) and plenty of leafy greens (no, I am not afraid of fiber).
ReplyDeleteWhen I travel to the US, it screws up my digestion within about three days, Japan usually, too. This was the same even before I started LCHF and IF.
I originally attributed this to the fact that I usually eat way more protein (beef in the US, seafood in Japan) than at home, but I tried keeping up IF and not have too much meat, made no difference. I also tried staying away from (usually in the US, chlorinated) tap water, PUFA, bromated bread, and I even gave up on airline food once, but I can't seem to escape my fate.
So there could be a strange ingredient in US food that does this.
I have not read up on optimal diet, but my impression is that you want to have healthy gut bacteria and feed them with fiber. They will make nice short and medium chain saturated fatty acids for you...
Ned, makes sense. I suspect that fructose will pan out the same. At peak blood fructose (or alcohol) level there is inappropriate lipolysis, the insulin probably shifts the FFAs in to hepatocytes. The hepatocytes then release VLDL under low insulin conditions which (I would guess) might target those VLDLs to visceral adipocytes... Need to read more about the relative insulin sensitivities of visceral adipocytes. That's before we get on to GHr negative adipocytes and insulin sensitivity and dwarves and small mice............
ReplyDeletePeter
In the context of steatorrhea that would just be a transitional issue on the way to my body adapting, right? I mean, humans must assimilate fat in their bodies to some extent, perhaps mine just needs time to adjust to it being the predominant macro instead of something to expel if found in "excess".
ReplyDeleteAlso I've been tending toward liquid meals as of late due to a demanding profession. I consume heavy cream, as much as my body demands, but I add about 70gms of protein from whey to it, and around 50 GMs from dextrose. I use dextrose so it's purely glucose, thereby bypassing the trouble found with fructose's absorption. I also take a multivitamin daily and eat chicken hearts/eggs/beef hearts/beef when I get a chance. So my question is - with my carbs totalling a little over 50 GMs factoring the heavy cream & whey, is it safe to consume the majority of my carbs in that context from dextrose?
Jay, have you tried basing similar macros on something more like food?. I suspect six eggs might be rather more useful than whey protein and a multivit.... Just a thought. It's that eternal question, why is there so much cholesterol in an egg? Because that's how much it takes to make a healthy chick.
ReplyDeletePeter
I have, but in many cases I don't have the luxury of cooking meals without cutting into my hours of rest.
ReplyDelete