Great Barrington Declaration (2)

Sorry folks, more COVID-19, more anger. Again a screen shot from part way down this page here, published by the UK government.

https://coronavirus.data.gov.uk/details/deaths?areaType=region&areaName=London

It looks like this:

That dark blue, slightly wavering, rising line is the deaths of the over 60s with a positive PCR. Some really will be COVID-19. They should never have been exposed to the virus. Should they have wished to, they should have been allowed to stay shielding and they should have been helped financially and practically to do so. Anyone, of any age, who became seropositive in the first wave could safely be in close contact with them today, no need for loneliness this winter. This course should have been offered as an option.

It wasn't.

The lower, paler blue line is the deaths of the under 60s. This line runs along the x axis. Very, very few people in London under 60 years of age have died with a positive PCR this Winter. Not many in the Spring for that matter either.

Shutting down much of the country, including London, in to Tier 4 lockdown (welcome to my world) has done nothing to protect the vulnerable over 60s and wasn't needed for the under 60s.

This is exactly why I signed the Great Barrington Declaration, to avoid this. Focused protection for those who need/want it, lots of it. Throw money at them. Let the rest of us get on with life.

Boris Johnson and Matt Hancock are politicians. I expect nothing from them, they're not exactly bright. But Whitty and Valance have no excuse. They must know what the above graph looks like. They know. Both of them were taught immunology once upon a time (implausible though that seems nowadays).

The lockdowns have done nothing to protect Norfolk from our Winter catch-up. We have no focused protection for the elderly. It's wrong.

Sorry for the rant.

Happy New Year.

Peter

IgG IgA and sniffing a virus which stinks

Just a quick post, possibly the last for a while as I have quite a lot going on off-blog at the moment and time will be scarce over the next couple of months.

I have downloaded this graph from the UK government website which can be accessed at

https://coronavirus.data.gov.uk/details/deaths?areaType=region&areaName=London

Obviously it will be out of date within 24h but, unless you are Whitty or Vallance, you will not be expecting the line to suddenly spike upwards to give (sarcasm warning) 4000 deaths per day for the whole of the UK next week.

These are the figures for London:

London is at herd immunity. Even with the second wave.

I'd like to perform a thought experiment. Let's imagine Fred. Fred lived in Lewisham and was a typical victim of the lipid hypothesis, but had not progressed to frank diabetes or significant metabolic syndrome. He contracted SARS-CoV-2 in mid February, coughed for three days and recovered. He wasn't tested, didn't go to A and E and was not a Spring peak statistic. He has 1) T cell mediated immunity 2) mucosal surface IgA immunity and 3) possibly some antibodies, neutralising, though these may not be at a level detectable in routine serology. He is, absolutely, not on the graph for the April peak in deaths.

Here comes the sad bit.

Fred has had recurrent stomach pain throughout the Summer. He keeps taking the Gaviscon and it does a bit of good but not much. The pain is never quite bad enough to go to A and E, certainly not in the face of the then current viral pandemic.

Fred's problems continue on and off until early November at which point he collapses with incapacitating stomach pain and profuse vomiting. He is still immune to SARS-CoV-2.

He is admitted to hospital and worked up for acute pancreatitis. It is difficult to describe how appalling this is as a medical emergency, and yes, it is triggered by polyunsaturated fatty acids, thank your cardiologist. After a day or so on a medical ward he is transferred to the ITU, just after his SARS-CoV-2 PCR result comes back positive.

Fred is immune to SARS-CoV-2. His respiratory system is covered in IgA. Any SARS-CoV-2 he picks up in the hospital will simply stay there, bound and unable to invade.

But if you take a swab from his throat/nasopharynx, especially in a hospital area with even minor exposure to SARS-CoV-2, the fact that that some viral particles are bound by IgA in a fully immune person makes no difference to a PCR machine running at 40 amplification cycles. He will come up positive.

Pancreatitis comes with a significant death rate. Fred dies (he's imaginary, no need to be sad, for Fred anyway) on the 28th of November 2020. What did he die of? Obviously he is in the stats for COVID-19, second wave, London. At the right hand end of the graph at the top of the post.

Here in the UK deaths at home have been running at 1000/week above normal levels since the lockdowns started in March and this has not diminished. Over 75% of these do not get COVID-19 mentioned on their death certificate. Fred made it to hospital, bound a few stray SARS-CoV-2 particles to his IgA and so died with COVID-19 by PCR amplification, which does get mentioned on his death certificate.

The chances of London not having reached herd immunity in the Spring seems vanishingly small. Certain pockets appear to have been missed and are catching up at the moment, the virus is, absolutely, still around and, absolutely, still making some people very, very ill.

But I think Fred is also common.

It is easy for anyone with a smattering of immunology and basic knowledge about PCR technology to access the data for London, which make this clear.

I'm loathe to attribute motive but SAGE has been after an extended full lockdown ever since before lockdown 2 started and they needed more than genuine infection figures, or even deaths, to get it.

I got three rapid sequential texts at 11pm on Saturday night explaining about the "new, 70% more contagious" strain of virus spreading in the South East and the essentially total shutdown of the area, just to the south of us here on the Norfolk/Suffolk border, which was going to happen at midnight.

I couldn't get back to sleep.

I was angry.

I'm well aware of the state of COVID-19 around the UK and how areas spared in the Spring are catching up now. Norfolk will be one of these. This is not trivial.

But those late night texts about a massive change in policy based around a mutation and what I guess is garbage modelling (you think that the 70% increase in transmission rate comes from some sort of data? Haha. I would bet Ferguson modelled this. It will be as good as his previous models. And then it won't be a prediction, just a "scenario", when it turns out to be bogus) are frank psychological manipulation using fear. Bullying on a national scale.

I'm left wondering if those people who control the Prime Minister and used this "tweak" to force the lockdown they so desperately wanted were actually expecting the channel crossings to be immediately closed?

They should have been, given that we are living through times of a global pandemic of stupidity. But then, they are part of the problem.

Peter

IgG IgA and sniffing a virus

Basic immunology 101, ignoring T memory cells and cell mediated immunity..

If you contract a respiratory virus it colonises your nose/throat/windpipe. If you are unlucky it will also colonise your lungs and you might well be headed for a week or two in the ITU.

If it doesn't, you get better.

If you are re exposed to the same virus a month later you will not become ill unless you have something very, very wrong with your immune system. But might you transmit the virus still?

You can track the response of your immune system to the virus by tracking serum antibody production. The immediate effect is to generate IgM antibodies. These fade after a few weeks and are used clinically as a marker for recent infection. After a week or so you make IgG antibodies. These are present for a few months or even for life, depending on which virus we are talking about and whether there is continued exposure. If they are "neutralising" antibodies they will actually stop the virus invading cells by attaching to the cell-invasion protein of the virus. They are protective against illness.

There is another class of "poor relation" antibodies, the IgAs. These are mucosal cell surface produced antibodies. They are produced on the membranes of your nose, throat, trachea and possibly lungs if the virus gets that far and you survive.

IgA largely stops the virus becoming re-established in your nose on re-exposure. Neither IgM nor IgG, even if it is a virus neutralising IgG antibody, is going to do this.

Just to avoid controversy (and because the paper is handy) let's look at mice vaccinated against influenza using an adenovirus vector vaccine. The group used exactly the same vaccine in two groups of mice, in one they gave it intranasally, in the other intramuscularly.

Reduction of influenza virus transmission from mice immunized against conserved viral antigens is influenced by route of immunization and choice of vaccine antigen

"Here we demonstrate that transmission reduction is more effective when mice are immunized against A/NP and M2 intranasally than via the intramuscular route"

The intranasal route stimulated marked IgA production. The intramuscular route produced a minimal IgA response. Once vaccinated the group then challenged the vaccinated mice with field virus and assessed the ability of those vaccinated mice to transmit the field virus to non protected mice.

Intranasal, IgA generating, vaccination reduced transmission by 88.2%.

There is nothing surprising about this.

I fully expected the same vaccine given intramuscularly to do nothing at all to reduce transmission but it did, oddly enough, reduce transmission potential by 47%. Of course the question to be asked is whether this 47% transmission rate reduction would allow a vaccinated care worker to safely nurse your granny during an influenza pandemic.

You also still have to ask whether an 88.2% reduction in transmission might make a care worker safe to nurse an elderly person.

An adenovirus vector vaccine will induced an immune response to the protein coded for in the mRNA built in to that vaccine. If injected in to a muscle it should induce IgG in the bloodstream to that protein which, if neutralising, should protect against illness. That's good, but limited.

Contrast that to a genuine field virus infection. It starts in your nose, spreads to your throat and then down your windpipe to give you a marked production of membrane based IgA throughout the airway. It is going to induce IgA production to a whole host of viral proteins, not just the one or two forms of IgGs generated by a vaccine (even if given intranasally to generate some IgA). Some field antibodies will be very useful, some less so.

It seems to me that the probability of reducing or even eliminating viral transmission might be much better from a field virus infection than from a limited antibody response generated by an vaccine, even if given intranasally.

Quite what might happen if you combined intranasal and intramuscular administration, or even gave two doses of intranasal vaccine a few weeks apart are open questions for mice in influenza models. Yes, a model is only a model.

How much of this might be generic to respiratory viruses in general I don't know but I would be amazed if it wasn't.

As always there are a slew of questions which follow on from this concept but I'll stop here with my fondness of IgA inducing vaccines and particularly of asymptomatic infections. Having said that, I would qualify it as a vet. Anyone who has had the pleasure of administering an intranasal vaccine to a 40kg aggressive dog who is voting against said intranasal vaccination with his teeth is another matter. Luckily you can get it in through a muzzle on a good day. 

Peter

FIP vaccines etc

This post is just some random musings about coronavirus vaccines, most clearly in cats. The rest is speculation.  As an introduction here is the abstract-like entry for a book chapter pulled up by Duckduck from 'tinternet. It sums up pretty much what I recall from back in the days when I was a clinician dealing with the horrible disease of Feline Infectious Peritonitis (FIP), derived from complications of Feline Enteric Coronavirus infection. No author is stated but if I was an editor looking to have a chapter written about FIP I would, without any doubt, send the request to Niels Pedersen, who authored this (very long and involved) review:

A review of feline infectious peritonitis virus infection: 1963–2008

The chapter abstract summarises the interesting bits of the Pedersen's review nicely:

Coronaviridae

In Fenner's Veterinary Virology (Fifth Edition), 2017

Immunity, Prevention, and Control

Feline infectious peritonitis is not controlled easily; control requires the elimination of the virus from the local environment, whether this is the household or the cattery. This requires a high level of hygiene, strict quarantine, and immunoprophylactic measures. Because kittens acquire the infection from their queens, early weaning programs have also been used in attempts to interrupt virus transmission.

The development of a safe and highly effective vaccine remains elusive, even with the availability of bioengineering approaches. The only commercially available feline infectious peritonitis vaccine contains a temperature-sensitive mutant virus, based on a serotype II virus. The vaccine is applied to the nasal mucosa to reduce virus replication and antibody formation. Under these conditions, a cellular immune response is favored, and some protection putatively is achieved. Vaccination of infected, seropositive adult cats is not effective. In addition, experimental challenge of vaccinated cats has resulted in “early death” due to feline infectious peritonitis in some cases.

A broad spectrum coronavirus protease inhibitor drug has recently shown considerable therapeutic efficacy for treatment of cats with feline infectious peritonitis, a finding that suggests the disease might in the future be treated with antiviral drugs.

What is clear from FIP vaccination is that antibody production (or the administration of hyperimmune serum or pure IgG antibodies) in the absence of a cell mediated immune response, is lethal on challenge of kittens with a field strain of FIP virus. The serum is harmless, the IgG is harmless, the vaccine is harmless. What matters is how the disease progresses when field virus meets the antibody replete host. The effect of a vaccinia virus vector vaccine was described here (you only really need to read the title, it says it all):

Early Death after Feline Infectious Peritonitis Virus Challenge due to Recombinant Vaccinia Virus Immunization

which could reasonably be described as a bit of a booboo.

To summarise: Vaccines which stimulate antibody production without stimulating cell mediated immunity are a problem. This is Antibody Derived Enhancement. It's real. It has plagued (no pun intended) certain vaccines, obvious for FIP but Dengue Fever vaccine is a similar but non-related example in humans.

I'll leave FIP alone now except for adding that work with the reagent GS-441524 suggests that FIP is no longer the invariable death sentence which it was two or three years ago. People who have worked clinically with FIP, or lost cats to FIP, will understand the awe that this drug inspires. I hope it gets used sensibly.

Anyhoo.

I was listening to Radio 4's The Life Scientific which featured an interview with Prof Sarah Gilbert from Oxford, heavily involved in the development of an adenovirus delivered vaccine for protection of humans against SARS-CoV-2.

Apart from how genuine and extremely bright she is the main thing I recall is her comment that she was very pleased that the vaccine she was developing produced a robust cell mediated immune response in additions to stimulating antibody production.

This is excellent and is all that you could ask of a vaccine where antibodies are frequently high and ineffective well before admission of patients destined to die of COVID-19 complications in the ITU.

It looks like cell mediated immunity is what matters. That antibodies are non protective is also suggested by the extremely poor results using antibody rich serum from recovered patients to treat unwell patients with COVID-19. There is no suggestion that serum treatment did direct harm, just it didn't do much good.

So the major question this poses is how much good the vaccine might do in patients who are going to become ill with COVID-19 in the future. It is not an unbelievable stretch of fantasy to suggest that the defining characteristic of people who are going to go on to become seriously unwell after exposure to SARS-CoV-2 might just be those are the ones who are unable to mount an effective cell mediated immune response.

How well might the T cells of an 80 year old, morbidly obese diabetic respond to the vaccine, assuming they are not very likely to respond to the field virus?

We can but hope that if they do fail to develop cell mediated immunity then at least their antibody response (which will still happen) does no harm. And we can hope that cell mediated immunity response has been carefully assessed in the population to which to a COVID-19 vaccine is being rolled out as of today in the UK... 

Otherwise it's a bit of an experiment on many, many people's grannies.

Peter

Podcast with Dr Paul Saladino (2)

Part two is up, mostly about the glycerophosphate shuttle...

Peter

Protons (65): Fatty acids vs glucose and ROS generation

I've had this paper for some time:

The CoQH2/CoQ Ratio Serves as a Sensor of Respiratory Chain Efficiency

It really grabbed me as it was one of the earlier references to supercomplex assembly of electron transport chain components, failure of C57Bl/6 mice to manage this correctly due to a truncated supercomplex assembly protein and the deconstruction of excess complex one when electrons were fed in to the ETC via electron transporting flavoprotein dehydrogenase. So it's a great paper of enormous scope.

But there is more. Dave Speijer has a great discussion of why mitochondrial preparations are so hard to interpret because they are so far away from the in vivo situation and preparation artefacts are massively influential of results. It's in here on page 4110 if you'd like to browse.

Back to the Guarás paper. They got out of the problems of using isolated mitochondria by using intact fibroblast, treating them with a cell permeant dye which becomes fluorescent on exposure to ROS, followed by flow cytometry to assess ROS production. Then they could treat the cells with glucose or fatty acids +/- very low dose rotenone, which blocks RET without having the unacceptable off target effects of higher doses.

This is what they got. Glucose was 5mmol/l and FFAs, mixed types, were supplied bound to albumin at 1000micromol/l. Both quite physiological. Here is what they got (Fig 6, section H), we can ignore the galactose results:

So mixed FFAs produce roughly twice the ROS produced by physiological glucose. The effect is markedly reduced by inhibiting RET through complex I.

Sadly no one has done the experiment to compare saturated fatty acids, MUFA or PUFA on the generation of ROS. Still less to look at the effects of background glucose elevation to represent the immediate post prandial period, with or without insulin. But the basic proof of concept is there.

Nice paper.

Peter

Here we go in to Lockdown 2

This is the number of daily positive PCR tests (rather than genuine cases) in the UK, via Worldometers, graphed from the UK government website data. I've added an arrow to indicate the start of Lockdown 2 for those of us living under peak incompetence.

And here are the ICU admissions for the current wave, in orange. Ignore the dramatic drop at the end of this line, it probably represents under reporting because it takes time to update the database for the last 24h and these stats come out at teatime every Friday. Again these are data for time immediately before Lockdown 2:

Will it Lockdown 2 work?

Pretty safe bet it will because PCR positive test numbers have already plateaued, ICU admissions have plateaued and are probably falling, both over the week pre lockdown.

Overall it looks like we continue to head towards herd immunity despite all attempts to stop this and in the face of minimal protection for the vulnerable. Deaths have not plateaued yet, that will lag a few weeks behind the peak in positive test results.

Any modelling scenario which did not have these data as a future possibility when it was run at the start of October should perhaps have its validity questioned. That'll be the one with the 4000 deaths per day as a possible scenario, in particular.

Listening to the modellers is like listening a cardiologist espousing the benefits and "death-preventing" effects of statins. Except for lockdowns there is no equivalent to the easy option of dropping your statin prescription in the bin.

Will Lockdown 2 end on the 2nd of December?

Hahahahahahahahahaha

Peter

Linoleic acid makes you hungry

This paper reports what happens to hsCRP in people of differing fatty acid desaturase genotypes when you increase their linoleic acid intake from around 4% of calories to around 11% of calories. It's neutral or bad, depending on your genetics. Which is irrelevant to anyone remotely informed about what a human LA intake might reasonably be. So we can ignore the research on hsCRP.

Inflammatory response to dietary linoleic acid depends on FADS1 genotype

Two things come out that are worth noting. First is that, from Fig 4, that increased dietary LA mostly decreases the arachidonic acid in plasma phospholipids and cholesterol esters. I made a throw away comment in a previous post that I would expect supplementing any C18 PUFA would inhibit the formation of any C20 and C22 fatty acids. I got lucky on that one, AA levels mostly dropped with LA supplementation, one didn't change.

Much more interesting is the effect of the intervention, irrespective of genotype, on food intake. Like this:

"Based on food records, energy intake was significantly increased during the intervention period, which could be considered a third limitation. However, there were no changes in body weight or BMI, and an increase in energy intake was similar in both genotype groups. It is likely that the increased energy intake was at least partly related to the fact that oil consumption was carefully recorded during the intervention period."

I think we can describe this "likely" effect as ad hoc hypothesis number 3264.

A more reasonable ad hoc hypothesis is that increasing your linoleic acid intake from 4% of calories to 11% of calories makes you hungry. If this change were to have been caused by a projected loss of half a kilo of ingested lipid in to adipocytes over a year, that would be less than 50g per month. Easily masked by a number of biological variations.

Peter

Podcast with Dr Paul Saladino

 I had a very pleasant chat with Paul Saladino.

It was quite a long chat and there were still lots of places that we did not have time to visit...

Peter

Great Barrington Declaration

 This is really a job for twitter but that's not my platform.

Great Barrington Declaration

I've signed.

Peter

Full blown linoleic acid deficiency: speculation

 Tucker Goodrich emailed me the link to this lovely paper from the 1930s

ON THE NATURE AND ROLE OF THE FATTY ACIDS ESSENTIAL IN NUTRITION 

and included it in a blog post

Fat and Weight Gain (a Note to Peter) and the Essentiality of Linoleic Acid

TLDR, grossly linoleic acid (or the arachidonic acid derived from it) deficient mice are small, emaciated and lose a ton of water through their skin. Think superoxide.

It's an interesting situation, with a number of possible explanations and the sort of data you might expect from 1930, good for its time but we're not going to get the massive detail which people struggle to interpret nowadays.

I started off alongside the authors and caloric loss due to the evaporation of water from both the "leaky" skin and possibly from "leaky" lungs. If you have ever tried to keep a mouse warm under anaesthesia while it breathes anhydrous cold gas and is clipped and water/alcohol prepared for surgery you will sympathise. If not, you can take my word for it that without serious attention to heat conservation, their temperature drops like a stone.

The mice lose about 10ml of water per day through their skin. With a latent heat of vaporisation of 0.541kcal/g this means the 10ml of water steals about 5.41kcal per day of energy as lost heat, just to evaporate the leaked water. That's about an extra gram of carbohydrate or protein they would need.

But the mice were ad lib fed. They may have been pretty sick from LA deficiency but they managed to eat exactly as much as the healthy mice did each day. I find it implausible that they were so skinny because they were simply too ill to manage an extra gram of food. There is absolutely no doubt that they were very sick, but I still don't find this plausible for the emaciation.

A simple extrapolation from high PUFA diets facilitating fat loss in to adipocytes to the converse, that very low PUFA diets fail to allow fat storage is nice but seems very unlikely because the curative dose of linoleic acid seems too small to represent a supply of calories for bulk oxidation.

My core question relates to the failure to store lipid in adipocytes, with a spin off question in to the poor health of the fat free rats. This is all guesswork and speculation.

I have to accept the possibility that it might be as simply as that you cannot build a functional cell membrane or mitochondrial membrane without some bendy/fluid molecules. Given an inadequate fluidity to the mitochondrial inner membrane I can see that molecules such as CoQH2 or reduced cytochrome C, which move within/over a fluid inner mitochondrial membrane might lose electrons prematurely to molecular oxygen if they cannot reach their docking site in the next complex down the ETC. That a continuous, pathological loss of electrons from carriers to molecular oxygen, to give inappropriate superoxide and H2O2 generation, would lead to unrestrained insulin resistance and failure to grow, especially failure of adipocytes to grow, seems to be a plausible explanation.

As Burr and Burr comment, the kidney is also a very energy dependent and might well fail given a failure of insulin signalling due to excessive H2O2 generation. While the rats would lack ROS damage to membrane lipids they would not lack ROS damage to cellular proteins or DNA. The cells, if insulin signalling cannot occur due to excess H2O2 generation, would also be calorie starved as well as ROS damaged.

Quite why the tails fell of of the rats is beyond even my speculation ability.

So. The failure of adipocytes to grow suggests severe insulin resistance within those adipocytes. More generalised application of this idea would lead to explaining failure of the whole rat to grow.

Who knows what actually happened?

Peter

Continued:

I've long carried the idea in my head that PUFA depletion might be protective against radiation induced injury. I think I picked this up early in my low carb journey, probably from a Ray Peat follower. But that will have been over 15 years ago and I am unable to locate where this idea came from. So I went looking on Pubmed and opened a whole can of worms. Some of which are interesting.

The first is that rats fed a completely fat free diet are at increased risk of dying from radiation injury. That was this one:

THE EFFECT OF FAT LEVEL OF THE DIET ON GENERAL NUTRITION

XIII. THE EFFECT OF INCREASING DOSAGES OF X-IRRADIATION

ON THE PROTECTIVE ACTION OF FAT ON RADIATION INJURY

"More recently, it has been observed that the survival time of male rats, as judged by the intervals at which an LD25, an LD50, or an LD75 were reached, or by the average length of survival, was progressively improved when ethyl linoleate was given in doses of 10, 50, or 100mg daily (Cheng et al., '54)."

The same lab has produced at least four studies to support this finding.

Giving a rat 10mg of a source of linoleic acid will have no effect on substrate oxidation. But it might well allow the development of an effective electron transport chain which is less likely to release a random excess of electrons to molecular oxygen.

Of more interest is this study. It's not clear (to me) whether the diets contained 10, 20 or 30% of cotton seed oil by calories or by weight. Low PUFA diets (butter) were ineffective in small amounts but effective at 20% or 30%:

Deleterious effects of high fat diets on survival time of X-irradiated mice

"At levels of 2% or 10% of the diet cottonseed oil and margarine fat increased survival time over that on the fat-free ration. When these fats were fed at higher levels ( ie. ~ 20% or 30% of the diet), however, survival time was decreased below that obtained at the lower levels of supplementation."

My take home is that rats do, absolutely, need a few milligrams of linoleic acid. Notice that the amounts used in all of the studies are in the same ball park as found by Burr and Burr to prevent their fat deficiency syndrome. I think it is an interesting speculation that LA is particularly need to manufacture an effective membrane for the ETC, especially when electrons are going to be knocked around by x-ray irradiation over and above background radiation conditions. As the dietary dose increases then the deleterious effect of the PUFA eventually predominate, certainly in the radiation injury models.

Interesting findings.

Peter

Prof Sunetra Gupta

I first came across Prof Gupta as an invited speaker to one of the Royal College of Pathologist seminars, now viewable on-line at

The COVID 19 pandemic: epidemiology*

*Prof Gupta is at Oxford, not Imperial College as the RCPath intro slide incorrectly shows. We all know about the Imperial College modellers.

I thought she was talking sense at the time and that impression has not changed since. I notice that she has been very active recently in the media and I happened to pick up this interview via Faceache:

The Spectator interview

I've pulled this one out from many videos because it answers the question as to what an incompetent Prime Minister says when presented with someone who is telling him that he has done everything wrong. It's near the end so I've clipped out my favourite eight seconds:

Clearly there is no way, ever, that any government is going to say that they have screwed everything up about this pandemic. Completely.

Especially if they have. And honesty is not exactly a hallmark of Boris Johnson.

Peter

NB A more competent government in power would probably have done the all wrong things too, but much more effectively. That's a scary thought. I am seriously conflicted about this.

Aaargh BROKEN LINKS

UPDATE

Right. I've been back to the broken links issue and have noticed that, when you click on a link to a "search term" you get a blank Pubmed page. However in the URL of this broken link there is a complex set of gobbledygook but very close to the start is the PMID that the search term has previously pointed to. So in the post

https://high-fat-nutrition.blogspot.com/2007/10/physiological-insulin-resistance.html

the link to the paper by Wolever is broken. 

The URL above the blank Pubmed page from the link is this:

https://pubmed.ncbi.nlm.nih.gov/?Db=pubmed&Cmd=ShowDetailView&TermToSearch=10889799&ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum

and 10889799 is the PMID. Pasting this in to the search box gets you to the paper originally linked to so

https://pubmed.ncbi.nlm.nih.gov/10889799/

now gives access to the abstract as:

Dietary carbohydrates and insulin action in humans

After that it's a Sci-hub job.

Phew.

Peter

BROKEN LINKS

Over the years I have slowly learned how not to blog.

For one thing, never use hyperlinks embedded as "here" or "these people".

Always cite the paper title, then anyone can copy paste this in to Duckduck or Pubmed and they can then side step the broken link when it goes down, as it will.

In the very early days I used the Pubmed search result URL as the hyperlink. This appears to have been fine for the last 15 years or so but recently Pubmed updated and all of those links have been lost. If a hyperlink from a simple word like "here" used to go to a search result URL it will be down and even I cannot always relocate the original paper.

Sometimes even if I know exactly which paper it was it's not always possible to find on on my sprawling hard drive.

You learn these things as you go along. Damn.

Peter

SARS-CoV-2 loves linoleic acid

I haven't posted much about the SARS-CoV-2 virus or COVID-19. Mostly because I don't do politics on the blog and watching the utter incompetence of the UK government has been painful but not unexpected. It's fascinating how by having a completely wrong approach, but doing it so badly, that you can actually end up with a functional approach leading to herd immunity. Sadly it includes appalling rule by decree from Bojo.

On a brighter note, here's a snippet from the end of a fascinating paper looking at the detailed structure of SARS-CoV-2 and its fatty acid binding sites:

Free fatty acid binding pocket in the locked structure of SARS-CoV-2 spike protein

"We hypothesize that LA [linoleic acid] sequestration by SARS-CoV-2 could confer a tissue-independent mechanism by which pathogenic coronavirus infection may drive immune dysregulation and inflammation (35–37). Our findings provide a direct structural link between LA, COVID-19 pathology and the virus itself and suggest that both the LA binding pocket within the S protein and the multi-nodal LA signaling axis, represent excellent therapeutic intervention points against SARS-CoV-2 infections."

I think it was Puddleg who made a very reasonable comment about what, should he find himself in the ITU and someone tried to hook him up to a linoleic acid based intravenous emulsion, he would try to do. I think strangling them was involved.

The virus is looking to help the virus to make more virus, not to kill the host. A good plan to generate anabolic substrate might be activating peroxisomes to get all of that peroxisomal acetyl-CoA and cytoplasmic malonyl-CoA. Like this:

Infection-Induced Peroxisome Biogenesis Is a Metabolic Strategy for Herpesvirus Replication

and if we wanted to be a bit more specific we could take a lesson from Cytomegalovirus:

Cytomegalovirus Infection Triggers the Secretion of the PPARγ Agonists 15-Hydroxyeicosatetraenoic Acid (15-HETE) and 13-Hydroxyoctadecadienoic Acid (13-HODE) in Human Cytotrophoblasts and Placental Cultures

which uses good old 13-HODE derived from linoleic acid as well as 15-HETE from arachidonic acid to get what it needs. Both are potent peroxisome proliferation stimuli and are being used, probably also by most other enveloped viruses, to generate the lipid precursors needed to build more envelope. Hence their love affair with linoleic acid.

The fact that your cardiologist made you obese and diabetic as you become elderly (what ever your age) as a result of promoting hearthealthypolyunsaturates ties in neatly with the probability that linoleic acid might also markedly assisted viral replication in addition to triggering a cytokine storm.

The lipid hypothesis just never stops giving.

Peter

Protons (64) The miracle of fish oil (6)

Preamble: I started this current series of post about the ability of fatty acids with multiple double bonds to limit weight gain. To me, this is a paradox. Paradoxes are, without a doubt, the most productive sources for the development of an idea. Even as I started this current post I had no idea where it was going to end up and was bit surprised at where the metabolism took me. So be it. Let's begin.

Beta oxidation in peroxisomes consumes half the amount of oxygen as in mitochondria. The first step of oxidation of saturated fats runs like this:

R-CH2-CH2-COOH + FAD -> R-CH=CH-COOH + FADH2

In peroxisomes this is followed by

FADH2 + O2 -> FAD + H2O2

then

2xH2O2 -> Signalling -> Catalase -> 2xH2O + O2

The energy from FADH2 is released as heat and half the oxygen is regenerated.

The NADH from beta oxidation is of no immediate use in a peroxisome and has to be transferred to mitochondria before it can be utilised. I suppose it could be phosphorylated to NADPH for anabolism but I have no data on that. It's not clear how reducing equivalents might be transferred from peroxisomes to mitochondria. There is speculation about something along the lines of the malate-aspartate shuttle used to import cytoplasmic NADH in to mitochondria.

It's also something of a truism that peroxisomes cease beta oxidation at C8 and then export this (by uncertain mechanism) to mitochondria for completion of oxidation. Digging back through the reference trail leads to the origin of this as the finding that isolated peroxisome preparations happily oxidise lauric acid but won't oxidise caprylic acid (much). Clearly oxidising DHA will never produce caprylic acid directly because there are double bonds within the residual eight carbon atoms. What exactly happens to truncated DHA at the C8 length appears to be an unasked question.

So beta oxidation in peroxisomes produces heat, NADH, acetyl-CoA and signalling H2O2. And perhaps some caprylic acid from any saturated fatty acids being oxidised. It requires markedly reduced oxygen consumption and appears to result in proportionately lower CO2 production, which gives an unchanged respiratory exchange ratio (RER).

Going back to

Enhanced Peroxisomal beta-Oxidation Is Associated with Prevention of Obesity and Glucose Intolerance by Fish Oil-Enriched Diets

some of these things become clear. We have these measurements of oxygen consumption:

The round symbols are the fish oil fed groups. Average VO2 through 24h is reduced by fish oil from about 3500ml/kg/h to about 3000ml/kg/h, ie that's a just under 15% reduction.

Here are the RER figures, still fish oil as circles. As expected high fat diets show a low RER, low fat diets show the converse. The reduced O2 consumption is exactly balanced by a reduced CO2 production and the RER is still largely set by the dietary carbohydrate-fat ratio.

Clearly, under fish oil, approximately 15% of calories are being used to generate heat and anabolic substrate without consuming oxygen or being transferred to the ETC.  Provided there is enough fish oil to stimulate peroxisomal proliferation the changes are quantitively independent of the absolute amount of fish oil. 

So with fish oil at as low as 10% of calories, not all of which are PUFA, VO2 is dropped by 15% suggesting that the peroxisomes are activated and are oxidising more fatty acids than just the PUFA from the diet. Presumably on the low fat fish oil diet the peroxisomes are also metabolising palmitate and oleate derived from carbohydrate by de novo lipogenesis too.

If we go to this paper:

Peroxisomal and Mitochondrial Oxidation of Fatty Acids in the Heart, Assessed from the 13C Labeling of Malonyl-CoA and the Acetyl Moiety of Citrate

we can see, by clever carbon 13 labelling, that peroxisomal derived acetyl-CoA in cardiac muscle (and I would guess most other extra-hepatic sites) does not enter mitochondria, it all stays in the cytoplasm as malonyl-CoA.

These data are from perfusing hearts with docosanoate, a C24, fully saturated, fully peroxisome targeted fatty acid. We get lots of labelled malonyl-CoA in the cytoplasm, minimal labelled citrate in the mitochondria.

The next fascinating paper (HT to Peter Schmitt for the link) used erucic acid, another peroxisome targeted fatty acid.

Peroxisomal oxidation of erucic acid suppresses mitochondrial fatty acid oxidation by stimulating malonyl-CoA formation in the rat liver

In the liver peroxisomal oxidation of fatty acids generates acetate but this is still converted to acetyl-CoA and then malonyl-CoA without entering mitochondria. We know from the Randle cycle that malonyl-CoA is an inhibitor of fatty acid oxidation so it should come as no surprise that erucic acid feeding to peroxisomes inhibits fatty acid oxidation in mitochondria. So we end up with lipid accumulation within the liver, progressing to fatty liver and NASH. I have mention before that in rodent models of alcoholic fatty liver disease fish oil is one of the most effective generators of alcohol induced liver damage...

But perhaps the best line from this last paper is:

"Peroxisomal metabolism of erucic acid also remarkably increased the cytosolic NADH/NAD+ ratio..."

It seems very, very unlikely that fish oil will be any different.

We find ourselves in a situation where peroxisomal oxidation of fatty acids generates benign heat combined with large amounts of anabolic substrate and a high NADH:NAD+ ratio while requiring reduced oxygen consumption and simultaneously inhibiting mitochondrial fatty acid oxidation and shifting metabolism to glucose.

Does that look like a recipe for cancer?

It does to me.

I had no idea that there is a large literature looking at the role of peroxisomes in all sorts of cancer types. Woohoo, they are a drug target! Perhaps avoiding peroxisome activating fatty acids and their derivatives might be a better approach. Apart from accepted Bad Things like drinking erucic acid or 4-HNE (a superb peroxisome activator) we might ask serious questions about drinking bulk fish oil.

Perhaps don't.

Peter

Addendum: I recall this study (observational but not a food frequency questionnaire in sight), which I was fairly uncertain about back in 2013

Plasma phospholipid fatty acids and prostate cancer risk in the SELECT trial

Now I'm more convinced...

Protons (63) 4-hydroxy-2-nonenal (2)

Brief aside for a one-liner-ish post.

This study gives an idea of what happens when you drink 4-HNE:

A high oxidised frying oil content diet is less adipogenic, but induces glucose intolerance in rodents

Here are the diets. The rats on heated soybean oil (HO) ate relatively little so all of the other groups were partially starved to the caloric intake of the HO group.

and here are the weight gains (green circles).

Note especially how thin the 4-HNE fed rats (blue rectangle) were and how the fish oil fed rats (red rectangle), even under caloric restriction were still the fattest, fatter even than the fresh soybean oil fed rats. On the same calories.

This diet had no sucrose, it was starch based. Like the rodent chow in the last 4-HNE post which gave the greatest weight gain on DHA or EPA. Starch diets seem worse than sucrose diets when mixed with fish oil...

Back to 4-HNE. These rats were mildly glucose intolerant too. Glucose was ns different from controls throughout an OGTT but the area under the curve was greater under 4-HNE.

In this case we have, I would speculate, 4-HNE causing insulin resistance within adipocytes, limiting fat storage (ie reducing loss into adipocytes), so limiting hunger by actually reducing fat gain. 

And doing god only knows what other damage along the way to these un-arguably thin rats. As the authors suggest, the HO diet could even be destroying the beta cells of the pancreas...

Peter

Addendum HT to raphi for this link in the comments. Well, that's cool

4-hydroxynonenal causes impairment of human subcutaneous adipogenesis and induction of adipocyte insulin resistance

Protons (62) The miracle of fish oil (5)

Okay, its time to look at this paper:

Enhanced Peroxisomal beta-Oxidation Is Associated with Prevention of Obesity and Glucose Intolerance by Fish Oil-Enriched Diets

We have four diets, two based around low fat (10% fish oil or 10% lard), each with a little soybean oil thrown in. The other two were 60% of calories from fat, either from fish oil or lard, both with generous soybean oil added. Fatty acid composition was measured by gas chromatography. I've replaced the percentage of lipid as linoleic acid with percent of total calories as LA written in red.

Notice the study altered protein levels in addition to switching starch for fat. Talk about failing to control your variables.

Then we just have to feed ad-lib for eight weeks and look at the weights. In fact we can actually look at the fat mass in addition to weight, which is much nicer. We can also look at the energy efficiency, weight gain per unit calories absorbed. Note the columns have changed order, I've again added the linoleate percentages of calories in red, highlighted the energy efficiency in blue and circled the results of interest in green:

I did a rough back-of-the-envelope calculation for the number of mg/kg/d of DHA consumed by the mice fed the 10% fish oil diet. It works out as around 1250mg/kg/d on a semi-purified diet background, so probably in the peroxisome activating level.

Obviously the amount of fat stored roughly follows the LA content of the diet outside the green circle anomaly.

Notice that the "average energy absorbed" is lowest in the fattest group of mice. These animals are not making fat out of nothing. To understand this you have to go back to this image from a long time ago:

The top line is HFD (D12492, fed to Long Evans rats). All of the "hyperphagia" needed due to rapid weight gain occurs during the first 10 days and is only statistically elevated during the first 6 days. If the averaged food intake of the mice in the current study is lower than the brief "hyperphagic" phase this would explain the low overall calorie intake. The effect might be exacerbated in part due to the strain of mouse used, in this case the Swiss mouse, which is not prone to obesity in the way that many rodent strains are.

I started to look at these mice in terms of energy budgets. The mice are fed ad lib so are all going to eat exactly as much food as they need. No more, no less.

The high lard, high LA fed mice need 77.85kJ/d to meet basal metabolic rate, thermogenesis, cage exploration and this will also include a modest loss of calories in to their already distended adipose stores. They can do all of this on 77.85kJ/d. This is what they need.

The high fish oil fed mice should need very slightly less than 77.85kJ/d because they are lighter, so have less tissue to support metabolically, ie have minutely lower BMR and, again being lighter, it takes less calories to move themselves around their cage. They are also barely losing any fat in to their adipocytes. Despite all of these small combined contributions to decreased caloric needs they still have to absorb more calories (83.42kJ/d) than the fat mice to support a significantly lower weight and fat mass.

Clearly they are losing some of those extra calories but in this case the calories end up in peroxisomes rather than in adipocytes. I would predict that these mice will have a normal body temperature (this is tightly controlled in awake mice) but they will be physiologically adapted to dissipate excess waste heat. At 20degC this is easy for a mouse, it normally spends more calories on thermogenesis than it does on BMR at this temperature.

So the thin mice are unable to meet their basic caloric needs without having to "over-consume" food to make up the deficit induced by heat generation. In peroxisomes. They are not overeating and then using heat generation as a technique to stay slim. They are eating enough food to meet their needs but the lipid sources in their food are intrinsically and wastefully heat generating.

Just as the fat mice are fat because they lose calories in to adipocytes due to linoleic acid, so the skinny mice are skinny because they lose heat calories through their skin due to DHA in peroxisomes.

Ad-lib fed mice never over or under consume calories. They eat to meet their needs. Exactly.

Peter

Note that the mice fed 10% of calories fish oil "over-consume" to total 92.51kJ/d. They need more daily calories than the 60% fish oil fed mice because they are losing some calories in to adipocytes. That poses some more questions. As does the low oxygen consumption in the fish oil fed mice. An interesting paper. More to think about.

Protons (61) The miracle of fish oil (4)

There is a huge body of work on the requirement for DHA, its lipid peroxides, its use in the body but almost nothing about its bulk disposal. As in what happens to the excess DHA when you drink 60% of your total daily calories as fish oil, for weeks. As a rat.

I've been chasing tenuous leads as to whether DHA is catabolised in peroxisomes, in mitochondria or in both. I'd like a nice clear cut answer, but you can't always have what you want. It's clear that DHA can only be synthesised in peroxisomes because it requires elongation from ALA to eventually form a 24 carbon PUFA which is then shortened by beta oxidation to the C22 DHA. Only peroxisomes appear to deal with the beta oxidation of C24 fatty acids. For C22 and especially C20 it's not quite so clear cut.

On that basis I'm willing to go with peroxisomes as the main site of DHA catabolism, grudgingly and without hard data. Peroxisomal degradation is particularly difficult to justify from the simple FADH2:NADH ratio because DHA has so many double bonds that it's not going to drive reverse electron transfer through complex I. But it might be too fattening of course...

While searching I came across this study:

Enhanced Peroxisomal beta-Oxidation Is Associated with Prevention of Obesity and Glucose Intolerance by Fish Oil-Enriched Diets

which provides a number of points which need discussion, but for today I'm looking at following the reference trail back through DHA and peroxisomes.

The trail is good at level one backwards, with a nice paper on reagent grade DHA gavaged in to rats, but beyond that it drifts off into partially hydrogenated fish oil (goodness only knows what that contains but it undoubtedly induces peroxisome proliferation) and beyond that in to very long chain mono unsaturated fatty acids which do the same thing but neither helps me with DHA/EPA catabolism.

So I'll just start with the DHA gavage paper today

Docosahexaenoic acid shows no triglyceride-lowering effects but increases the peroxisomal fatty acid oxidation in liver of rats

The biggest problem with it is that for a lot of the work they were using group sizes of three rats. You don't do stats with n=3 group sizes, so I see it more of a proof of concept paper.

Rats were ad-lib fed semisynthetic diets (experiment I) +/- added cholesterol (experiment II). They were also gavaged with 500mg/kg, 1000mg/kg or 1500mg/kg of pure DHA daily for 10 days. Controls got nothing or palmitate 1500mg/kg/d. I'll come back to experiment III later.

Control rats grew at normal rat growth rate. DHA at 500mg/kg increased weight gain over the 10 days, 1500mg/kg did not, giving a comparable growth rate to controls. Using 1000mg/kg/d varied in effect but that's probably due to n=3 group sizes. Palmitate at 1500mg/kg/d is not obesogenic (well, whodathunkit?).

These are the numbers, relevant weight gains outlined in red:

Experiment III is even more interesting. Here they fed the rats ad-lib on a then-current 1993 style fairly high quality crapinabag, possibly something a bit like 5001. They gavaged EPA as well as DHA and had palmitate as control, all at 1000mg/kg/d, there was no untreated control group. This time we have n=5 rats. From the blue square palmitate gave 33g weight gain, DHA 52g and EPA 58g over 10 days. I particularly like this as DHA might be peroxisomaly directed but EPA, being shorter, less so. I get the impression this is not "all or nothing". DHA looks as if it might simply go through mitochondria if there is just a little of it around. If there is a lot it around it induces peroxisome proliferation and peroxisomal beta oxidation. Putting double bonds through mitochondria should produce fat gain, through peroxisomes less so. If you have my biases. Of course we have no idea re fat gain vs muscle gain in these rats.

The thing which struck me is how neatly you can control weight gain by choice of dose of DHA and by choice of background diet. I like it. Rats are so like people.


It's also interesting to look at Table 5

The column of interest here is outlined in red again. This is the ability to oxidise palmitoyl-CoA in the presence of potassium cyanide. Because KCN completely blocks the respiratory chain at complex IV any oxidation of palmitate in its presence is exclusively within peroxisomes. Increasing doses of DHA increase peroxisomal palmitate oxidation. Given high enough DHA ingestion peroxisomal activation appears able to over ride the weight gain effect of low dose DHA.

Summary: Low dose DHA causes increased weight gain in growing rats at 500mg/kg/d. At 1500mg/kg/d it doesn't, almost certainly through peroxisomal activation.

Adding DHA or EPA to a particularly healthy low fat/high complex carbohydrate diet might make the weight gain worse. In a rat.

Does this mean anything for humans?

Perhaps if you are going to take fish oil, take lots. Or, better still, none at all.

Peter

Oh, and, as far as I can see, no one has ever taken radio-labelled DHA and fed it to isolated peroxisomes or isolated mitochondria and looked at labelled metabolite or CO2 production. The test fatty acid has always been palmitate. Which is odd.

Protons (60) 4-hydroxy-2-nonenal

I've been re-reading Dave Speijer's

Being right on Q: shaping eukaryotic evolution

I cannot over emphasise how both broad and detailed this work is. This current post came from following a single link in the section on uncoupling.

Back in 2000 people were bulk manufacturing human uncoupling proteins using E. coli and assembling them within the membranes of synthetic lipid vesicles. They had problems getting the UCP1 to function correctly but eventually, by dint of an enormous amount of hard work, they found this requirement (the title says it all):

Coenzyme Q is an obligatory cofactor for uncoupling protein function

The UCP1 derived from E.coli could be activated by the addition of coenzyme Q, more specifically in its oxidised form CoQ. This is slightly counterintuitive as you might expect CoQH2 to be more of a signal that "excess" electrons were present in the ETC and that uncoupling to reduce the mitochondrial proton gradient might be a good idea.

Anyhoo.

The next snippet was provided by Brand's group

Superoxide activates mitochondrial uncoupling proteins

who used the oxidation of xanthine by xanthine oxidase to generate superoxide in-situ, to demonstrate that superoxide was, or could generate, the necessary co factor to allow UCP3 (in this case) to function. This is much more understandable because excess input to the ETC in the absence of a need for ATP is the classical situation for ROS generation and so ROS are more plausible as a signal to institute uncoupling compared to the oxidised version of CoQ.

Then comes this paper, again from Brand et al (which is the one I picked up from Dr Speijer's work):

Synergy of fatty acid and reactive alkenal activation of proton conductance through uncoupling protein 1 in mitochondria

The evil molecule 4-hydroxy-2-nonenal (4-HNE) is synergistic with fatty acids in activating UCP1. Physiological uncoupling is generally thought of as a Good Thing. 4-HNE as a Bad Thing. Perhaps we should be careful about making value judgements about molecules.

From an evolutionary perspective there is no obvious reason (to me) why UCPs might not be activated directly by superoxide itself but in this case the preferred solution appears to have been to allow superoxide to modify linoleic acid within/around the mitochondrial inner membrane into 4-HNE, which can then act as a cofactor to UCP1 to synergise, in this experiment, with free palmitic acid to dissipate the membrane potential and so to limit excess ROS production.

So UCPs in general appear to respond to an inappropriately high level of ROS generation by activating the safety valve of uncoupling the mitochondrial membrane potential. Linoleic acid derived 4-HNE is key to this process.




I have argued that the normal mechanism for limiting calorie ingress into a replete cell is for ROS to disable insulin signalling. And that PUFA fail to generate the appropriate ROS needed because they fail to deliver an appropriate supply of FADH2 to ETFdh and subsequent reduction of the CoQ couple. So PUFA allow an excessive, poorly controlled calorie supply. Eventually enough energy will be supplied that an excess of ATP combined with a paucity of ADP limits the activity of complex V, so membrane voltage will finally rise, the flow of electrons will back up and lots of ROS will finally be generated. At this stage there is still too much input, too little demand and a problem looking for a solution.

Uncoupling is one solution. Electrons can be allowed to continue to pass down the ETC and to pump protons but these protons are allowed back through the UCP, generating heat rather than ATP and reducing the membrane potential. Which will limit the ROS generation which might otherwise become too high.

Now, if you accept that PUFA are the cause of the situation and that uncoupling is the solution, which fatty acids would you expect to be the best activators of UCPs when uncoupling proves to be needed?

Correct. PUFA are the most effective protonophores when used by UCPs to reduce the inner mitochondrial membrane potential. As in:

Polyunsaturated fatty acids activate human uncoupling proteins 1 and 2 in planar lipid bilayers

Aside: It's worth reading the methods section of this paper. It gives insight in to a) how phenomenally difficult it is to set up models to look at individual protein functions in isolation and b) how far from physiological such models are. Difficult, extreme, necessary. But interpret with caution. And think about any requirement for 4-HNE. End aside.

Let's go up a level from the ETC to the cell plasma membrane and insulin signalling. If you are a cell and you are swamped with incoming calories but can only signal using ROS by the time that ongoing incoming calories are continuously too high, what other strategies might you apply?

How about augmenting the PUFA-inadequate insulin resistance by using 4-HNE to generate a few of the necessary extra ROS? As in:

The lipid peroxidation by-product 4-hydroxy-2-nonenal (4-HNE) induces insulin resistance in skeletal muscle through both carbonyl and oxidative stress

Additional cellular insulin resistance, supplied by 4-HNE, is a logical solution to a situation where insulin resistance is needed but is not happening appropriately. The role of 4-HNE can be viewed as being protective by uncoupling at the level of the mitochondrial membrane and also protective by augmenting insulin resistance at the cell surface membrane.

And to re-iterate again: Insulin resistance in adipocytes is synonymous with decreased fat storage and/or increased lipolysis.



I think it is very reasonable to assume that our physiology knows all about PUFA and how to deal with them. The end result may not always be what we want, but it will be adaptive. I think the context in which we are exposed to them is very important, especially the level of insulin, the rate of beta oxidation (which beaks down 4-HNE and related molecules) and the total quantity of linoleic acid in the diet. Getting 1% from mammoth fat is perfectly oaky. Getting much more on a ketogenic diet can be dealt with. Margarine on your baked potato might be a no-no.

I also think that bulk ingesting aged corn oil from a deep fat fryer might not provide a particularly physiological supply of 4-HNE.

But clearly, given the correct experimental set up, we can arrange that diets based around safflower oil can be less obesogenic than those based around lard, despite the very much higher linoleic acid content of the safflower oil. It provides a tool to understand papers like this one:

Differential effects of saturated versus unsaturated dietary fatty acids on weight gain and myocellular lipid profiles in mice

(HT to Amber O'Hearn for resurfacing the paper which has been on my "think about it" list for a long time)

which uses these diets

How the authors describe the diets is unimportant, all that matters is the PUFA content. Here are the weight graphs:

The minimum weight gains are the LF_PO at 1% PUFA (low total fat), over lain by the HF_CB (high total fat) but just over 1% of calories as PUFA. HF_PO is worst due to 4.5% of calories as PUFA. HF_OO diet is almost as bad with the same PUFA percentage.

Yet another aside: I would never argue that there is no influence of the lipid species available to be incorporated in to adipocyte triglycerides. All-palmitate would turn adipose to candle wax, all-linoleic acid into a liquid. So there are decisions made re storage vs oxidation taken at several layers above the ETC with are not unimportant but are not my forte. End aside.

But the safflower oil based diet, despite over 35% of calories as PUFA, is almost as weight gain limiting as the two low PUFA diets.

If you wanted to explain findings like this you would need to look at the level of heat generation, the level of 4-HNE production, the rate of oxygen consumption and possibly the level of insulin signalling in the post prandial period. But there are mechanisms to support a possible explanation.

Is linoleic acid a potential adjunct to weight loss? Mostly "no" is the short answer. But it appears to depend on how carefully you set up your study and what result you would like to get. Possibly how long you run the study for. Not that there any biases involved. It might also rather depend on how close you want to get to eating F3666 high PUFA ketogenic rodent food. And how many double bonds you might be willing to accept into your inner mitochondrial membrane lipids.

Personally, no thanks.

Peter

BTW

In the first paper CoQ probably works by generating the 4-HNE needed by UCP1 while CoQH2 doesn't. I'd speculate that because CoQ is an electron acceptor, which normally accepts electrons from the terminal FeS cluster of complex I, it might be looking to accept electrons from other sources in a lipid bilayer preparation. In the synthetic lipid by bilayer there are molecules of linoleic acid. Under conditions of available oxygen I see no reason why CoQ might not accept/steal a pair of electrons from a double bond in linoleic acid which would leave behind a reactive lipid radical which is a good candidate for combining with oxygen and eventually forming the 4-HNE needed by UCP1 to work efficiently. Just a guess.