32 replies to this topic

[RichardAlan]

I'm getting very confused here.  Sometimes I read that NR is broken down to NMN and then NAD  and other times I read that NMN is broken down to NR and then NAD. 

 

Does anyone know for sure which is which and if it's NR > NMN > NAD then why would anyone be taking NR?

[MikeDC]

Inside cells it is NR -> NMN -> NAD+.
But external NMN can’t enter cells without converting to NR first.

[RichardAlan]

Inside cells it is NR -> NMN -> NAD+.
But external NMN can’t enter cells without converting to NR first.

 

So you are saying NMN > NR > NMN > NAD ?   Now I am even more confused :-( 

[aaaaaaal]

I don't know about NMN but this is what it says on the Biotivia website:

 

 

 

Extracellular NAD+ undergoes conversion to intracellular NAD+ through dual salvage pathways. Oral NAD+ is metabolized into NAM (Nicotinamide) through the PRPP pathway using enzyme CD38 regulator. Oral NAD+ can also be metabolized into NR (Nicotinamide Riboside) through NR kinase process using NR kinases (NRK1 and NRK2) and enzyme CD73 regulator. The next phase is the intracellular conversion into NMN this is followed by final conversion into intercellular NAD

 

 

 

THE 2 SALVAGE PATHWYS FOR ORAL NAD+

NAD >> NAM >> into cell >> PRPP pathway >> NMN >> NAD+ (Uses enzyme CD38 regulator)
NAD >> NMN >> NR into cell >> NRK1/NRK2 >> NMN >> NAD+ (Uses enzyme CD73 regulator)
NR is sometimes converted into NAM during metabolism

NR kinases (NRK1 and NRK2) are predominantly expressed in skeletal muscle and, at a much lower level, in the heart (at protein level). No expression in brain, kidney, liver, lung, or pancreas. NR may be more functional to increase NAD+ levels in skeletal muscle cells.

NAD+ and NR have different mechanisms to form NMN or NAM for intracellular transition and these don’t interfere with each other. Both NR and NAD+ have single step process to form NMN which is used to increase the intracellular NAD+ levels.

 

Hope this is useful

Edited by aaaaaaal, 01 December 2018 - 06:46 AM.

[MikeDC]

So you are saying NMN > NR > NMN > NAD ? Now I am even more confused :-(

Outside cells NMN->NR
NR enter cell membrane
Inside cells NR->NMN->NAD+

I don't know about NMN but this is what it says on the Biotivia website:



Hope this is useful

Old data. NRK1,2 are in all organs. Old biology books are out of date. New data are coming out every day.

[LawrenceW]

Outside cells NMN->NR
NR enter cell membrane
Inside cells NR->NMN->NAD+

Old data. NRK1,2 are in all organs. Old biology books are out of date. New data are coming out every day.

 

Mike's bases his opinion of "Outside cells NMN->NR" on an old Dr. Brenner study. 

 

However, recent work done by Dr. Sinclair suggests that there is the possibility that there are as yet undiscovered transporters that facilitate the passage of NAD+ and NMN into the cell via the plasma membrane.

 

This is an interesting article that discusses the current thinking of academia.

 

https://www.leafscie...-cell-membrane/

 

Excerpt from the article:

"Can NAD+ or NMN pass through the plasma membrane?

Recently, there has been some debate in academia regarding the ability of nicotinamide adenine dinucleotide (NAD+) and one of its precursors, nicotinamide mononucleotide (NMN), to pass through the plasma membrane. It has been suggested that NMN cannot pass through the plasma membrane. However, there are some issues with this, given that there is research suggesting that this is not always the case and that NMN and/or NAD+ can cross the membranes of at least some cell types.

As far back as 2009, there is data that throws doubt on this assumption in the publication: Detection and pharmacological modulation of nicotinamide mononucleotide (NMN) in vitro and in vivo [1].

Also, evidence that intracellular NMN contents promptly increase when the nucleotide is added to the culture media indicates that plasma membrane is permeable to this nucleotide. These findings suggest that the pharmacologic effects of exogenous NMN in cultured cells and mice are due to cellular uptake and changes in NAD contents.

The matter is far from settled, as we can see from what Dr. David Sinclair says in his recent review Therapeutic Potential of NAD-Boosting Molecules: The In Vivo Evidence [2].

Whether or not NMN is taken up by a transporter is currently the subject of debate [3-4]. Brenner, Cantó and colleagues argue that NMN is not taken up quickly enough to invoke the presence of a transporter and that both NAD+ and NMN undergo extracellular degradation to generate permeable precursors that can be taken up by cells [4].

However, things are not that clear, and it is plausible that there could be specificity of cell types and NAD+ precursors. It could be the case that some cell types readily take up NAD+ or NMN and some do not; thus, finding out which do and do not should be the priority here. It is not at all unusual for such specificity to be encountered in biological systems, so this is something that needs to be determined during human clinical trials.

On the other hand, Imai argues that this is likely a cell-type-specific phenomenon and that some cell types can rapidly take up NMN [3]. If so, the identification of the putative transporter will help resolve the debate and help identify which cell types and tissues are able to transport NMN across the plasma membrane. Additional studies with isotopically labeled NAD+ precursors to trace the uptake and metabolism of these molecules should help answer these questions.

Dr. Sinclair also mentions here the possibility that there are as yet undiscovered transporters that facilitate the passage of NAD+ and NMN into the cell via the plasma membrane. Transporters (or membrane transport proteins) are proteins involved in the transport of ions, molecules, and macromolecules and they exist within and span the cell membrane allowing them to transport ions and molecules through them.

Transporters play an important role in cell survival, as these proteins make the interaction between the external and internal environment of a cell possible, importing and exporting substances in and out of the cell. In this case, Dr. Sinclair is suggesting that there are likely additional undocumented transporters that can facilitate the movement of NAD+ and NMN into the cell waiting to be discovered."

[stefan_001]

Here is a very recent study (posted in other thread) which indicates that alternative path doesnt exist or has little influence:

 

http://www.bloodjour...so-checked=true

Here we show that the NAD+-boosting agents Nicotinamide Riboside (NR) and Nicotinamide MonoNucleotide (NMN) reduce mitochondrial activity within HSCs through increased mitochondrial clearance via autophagy and possibly the Unfolded Protein Response mitochondria (UPRmt), leading to increased asymmetric HSC divisions as measured by asymmetric mitochondrial distribution in single cell pair-daughter analysis. This process was abrogated in Nrk1-/-;Nrk2-/- double knock out mice, which cannot incorporate NR into the NAD+ salvage pathway.

Edited by stefan_001, 01 December 2018 - 04:14 PM.

[Phoebus]

Here is a very recent study (posted in other thread) which indicates that alternative path doesnt exist or has little influence:

 

http://www.bloodjour...so-checked=true

Here we show that the NAD+-boosting agents Nicotinamide Riboside (NR) and Nicotinamide MonoNucleotide (NMN) reduce mitochondrial activity within HSCs through increased mitochondrial clearance via autophagy and possibly the Unfolded Protein Response mitochondria (UPRmt), leading to increased asymmetric HSC divisions as measured by asymmetric mitochondrial distribution in single cell pair-daughter analysis. This process was abrogated in Nrk1-/-;Nrk2-/- double knock out mice, which cannot incorporate NR into the NAD+ salvage pathway.

 

what does any of that mean? 

 

I have no clue 

[MikeDC]

Junk study.

[stefan_001]

what does any of that mean? 

 

I have no clue 

 

The authors in this study see an effect caused by NAD+ boosting by either administering NR or NMN. This effect does not take place when they do this with "Nrk1-/-;Nrk2-/- double knock out mice", That are genetically manipulated mice that miss the NRKs. In other words NRKs are essential for the process. The role of NRKs is "to transfer" NR into the cell. It therefore supports the theory that NMN -> NR -> passes into the cell and there is no direct NMN-> cell path

 

No idea why @MikeDC calls this study junk

Edited by stefan_001, 01 December 2018 - 07:43 PM.

[MikeDC]

My mistake. I thought asymmetric HSC division is bad. It is actually good.
The in vivo result is very good.

“In vivo, NR dietary supplementation resulted in a significantly enlarged pool of progenitors, without concurrent HSC exhaustion, improved survival by 80%, and accelerated blood recovery after murine lethal irradiation and limiting-HSC transplantation. In human xenotransplanted immune-deficient NSG mice, NR increased the production of human leucocyte progeny from hCD34+ progenitors. Our work demonstrates for the first time a positive effect of NAD+ boosting strategies on the most primitive blood stem cells, establishes a novel link between mitochondrial stress, mitophagy and stem cell fate decision, and unveils the potential of NR in vivo supplementation to improve recovery of patients suffering from hematological failure including post-chemo/radiotherapy.”

[MikeDC]

This again shows that people who think NR is expensive NAM is very wrong.
If all NR is degraded to NAM, NRK1 deletion will not make a difference.

[Phoebus]

when Mike realized the study was good for NR and bad for NMN he suddenly decided he liked it, lol 

 

 

[MikeDC]

when Mike realized the study was good for NR and bad for NMN he suddenly decided he liked it, lol

It didn’t say NMN is bad. I just don’t think NR can be bad for health.

[MikeDC]

Mike's bases his opinion of "Outside cells NMN->NR" on an old Dr. Brenner study.

However, recent work done by Dr. Sinclair suggests that there is the possibility that there are as yet undiscovered transporters that facilitate the passage of NAD+ and NMN into the cell via the plasma membrane.

This is an interesting article that discusses the current thinking of academia.

https://www.leafscie...-cell-membrane/

Excerpt from the article:
"Can NAD+ or NMN pass through the plasma membrane?
Recently, there has been some debate in academia regarding the ability of nicotinamide adenine dinucleotide (NAD+) and one of its precursors, nicotinamide mononucleotide (NMN), to pass through the plasma membrane. It has been suggested that NMN cannot pass through the plasma membrane. However, there are some issues with this, given that there is research suggesting that this is not always the case and that NMN and/or NAD+ can cross the membranes of at least some cell types.
As far back as 2009, there is data that throws doubt on this assumption in the publication: Detection and pharmacological modulation of nicotinamide mononucleotide (NMN) in vitro and in vivo [1].

Also, evidence that intracellular NMN contents promptly increase when the nucleotide is added to the culture media indicates that plasma membrane is permeable to this nucleotide. These findings suggest that the pharmacologic effects of exogenous NMN in cultured cells and mice are due to cellular uptake and changes in NAD contents.

The matter is far from settled, as we can see from what Dr. David Sinclair says in his recent review Therapeutic Potential of NAD-Boosting Molecules: The In Vivo Evidence [2].

Whether or not NMN is taken up by a transporter is currently the subject of debate [3-4]. Brenner, Cantó and colleagues argue that NMN is not taken up quickly enough to invoke the presence of a transporter and that both NAD+ and NMN undergo extracellular degradation to generate permeable precursors that can be taken up by cells [4].

However, things are not that clear, and it is plausible that there could be specificity of cell types and NAD+ precursors. It could be the case that some cell types readily take up NAD+ or NMN and some do not; thus, finding out which do and do not should be the priority here. It is not at all unusual for such specificity to be encountered in biological systems, so this is something that needs to be determined during human clinical trials.

On the other hand, Imai argues that this is likely a cell-type-specific phenomenon and that some cell types can rapidly take up NMN [3]. If so, the identification of the putative transporter will help resolve the debate and help identify which cell types and tissues are able to transport NMN across the plasma membrane. Additional studies with isotopically labeled NAD+ precursors to trace the uptake and metabolism of these molecules should help answer these questions.

Dr. Sinclair also mentions here the possibility that there are as yet undiscovered transporters that facilitate the passage of NAD+ and NMN into the cell via the plasma membrane. Transporters (or membrane transport proteins) are proteins involved in the transport of ions, molecules, and macromolecules and they exist within and span the cell membrane allowing them to transport ions and molecules through them.
Transporters play an important role in cell survival, as these proteins make the interaction between the external and internal environment of a cell possible, importing and exporting substances in and out of the cell. In this case, Dr. Sinclair is suggesting that there are likely additional undocumented transporters that can facilitate the movement of NAD+ and NMN into the cell waiting to be discovered."

Sinclair is just trying hard to make a case for NMN. So far for all cell types tested, there is no transporter for NMN. There is evidence that NAD+ can be transported through cell membrane, but not NMN.

[able]

Junk study.

 

 

My mistake. I thought asymmetric HSC division is bad. It is actually good.
The in vivo result is very good.
 

 

 

when Mike realized the study was good for NR and bad for NMN he suddenly decided he liked it, lol 

 

 

 

Yeah, too funny.  Perfect example of why you can't trust anything he says, ever.

 

Like a broken clock, he might sometimes be right, but just as likely to be picking bits of studies he likes, and ignoring the bits he doesn't like as "junk science"

 

Edited by able, 01 December 2018 - 11:14 PM.

[LawrenceW]

Inside cells it is NR -> NMN -> NAD+.
But external NMN can’t enter cells without converting to NR first.

 

 

Looks like we finally have a study that clears this up once and for all.

 

https://www.longecit...nmn-into-cells/

 

Seems like MikeDC had it dead wrong this whole time!

[MikeDC]

Looks like we finally have a study that clears this up once and for all.

https://www.longecit...nmn-into-cells/

Seems like MikeDC had it dead wrong this whole time!

For all practical purposes, nothing has changed. Slc12a8 Is only meaningfully expressed in intestine and can only transport a few percent of NMN before it is saturated in a few minutes. The expression of Slc12a8 in other cells is neglible. This has been confirmed by previous studies that NRK1 is required for NMN to increase NAD+. If Slc12a8 is expressed in a meaningful way, NRK1 will not be required. Nothing has changed. All previous studies are still valid.

[able]

For all practical purposes, nothing has changed. Slc12a8 Is only meaningfully expressed in intestine and can only transport a few percent of NMN before it is saturated in a few minutes. The expression of Slc12a8 in other cells is neglible. This has been confirmed by previous studies that NRK1 is required for NMN to increase NAD+. If Slc12a8 is expressed in a meaningful way, NRK1 will not be required. Nothing has changed. All previous studies are still valid.

 

Back from your 5th ban and immediately have to go peeing on all the threads, do ya?

 

 

 

As you know, the study found Slc12a8 is increased in older, sicker animals, in response to low NAD+ levels. It is a mechanism the body uses to try and make up for insufficient NAD+

 

You have absolutely no idea how much percent of NMN can utilize the Slc12a8 transporter.  None.  

 

They found it is not expressed at all in young, healthy animals, which is precisely what the Liu study used. So of course, no NMN utilized Slc12a8 transport in the Liu research.

 

It might be a very small amount of NMN that can utilize this new transporter, or it might be significant.  You don't know, so please don't go making things up that are not in the research.

 

It might not matter that much, or, it might prove a big advantage for NMN, and explain why research consistently shows better results with NMN in sicker animals.

 

One thing it does prove very conclusively, is that Dr Brenner was flat wrong when he keeps saying all NMN must go thru NR to enter cells.  And Dr Imai and Sinclair were right when they keep saying there must be a transporter.

[MikeDC]

If NMN works wonders in animals, why there is no human clinical trials results that have been published? Why there are 33 clinical trials registered for NR and only one is registered for NMN?

Show me some data and I will reconsider. In the meantime, you take your NMN and I take my NR.

[able]

If NMN works wonders in animals, why there is no human clinical trials results that have been published? Why there are 33 clinical trials registered for NR and only one is registered for NMN?

Show me some data and I will reconsider. In the meantime, you take your NMN and I take my NR.

 

Because NMN doesn't have a publicly traded company behind it, funding or encouraging studies?

 

You won't have to wait long.  As you know, metro biotech has completed numerous phase 1 studies and are ready to do phase 2 studies mid 2019. 

 

 

Metro International Biotech has conducted multiple IRB-approved human safety and bioavailability trials at a prominent Boston hospital, which demonstrated MIB-626 is well tolerated in healthy human volunteer subjects and raises blood levels of NAD+ and related metabolites.

 

 

 

https://www.metrobiotech.com/pipeline

 

They will also file 2 INDs to gain approval for use under orphan drug status, so it can be prescribe by doctors - something Elysium is pursuing, but Chromadex has give up on.

 

It fact, one of those INDs is for Frederichs Ataxia, which NMN proved successful for in treating mice, while NR was not successful.  

 

 

Metro International Biotech intends to file an IND in mid-2019 for Phase 2 trials in Frederich’s Ataxia.

 

 

 

Edited by able, 20 February 2019 - 01:54 AM.

[Colin]

David Sinclair "NR is converted to NMN and then NMN is immediately converted to NAD" on the Peter Attia Podcast, see https://peterattiamd.../davidsinclair/ at around the 1hr09min mark.  

[stefan_001]

Because NMN doesn't have a publicly traded company behind it, funding or encouraging studies?

 

You won't have to wait long.  As you know, metro biotech has completed numerous phase 1 studies and are ready to do phase 2 studies mid 2019. 

 

https://www.metrobiotech.com/pipeline

 

They will also file 2 INDs to gain approval for use under orphan drug status, so it can be prescribe by doctors - something Elysium is pursuing, but Chromadex has give up on.

 

It fact, one of those INDs is for Frederichs Ataxia, which NMN proved successful for in treating mice, while NR was not successful.  

 

https://www.scienced...55041311630482X

In summary, our results suggest that NAD+ depletion can induce severe neurodegeneration. Boosting NAD+ ameliorates neuropathological defects and markedly extends lifespan in an A-T mouse model.

 

They got more or less the same results with NR and NMN.

[stefan_001]

@able I keep wondering why you dont simply look at the expression atlas to get a view of Slc12a8 versus NRKs?

[able]

https://www.scienced...55041311630482X

In summary, our results suggest that NAD+ depletion can induce severe neurodegeneration. Boosting NAD+ ameliorates neuropathological defects and markedly extends lifespan in an A-T mouse model.

 

They got more or less the same results with NR and NMN.

 

 

Quote from NMN research:

 

“Remarkably, NMN administered to FXN-KO mice restores cardiac function to near-normal levels. “    (Martin, 2017). 

 

quote from NR study:

 

“In conclusion, NAD+ supplementation with NR in the FRDA model of mitochondrial heart disease does not alter SIRT3 activity or improve cardiac function.”(Stram, 2017)

 

I recall posting this several times last year, and Michael had some good points about reasons why the NR study wasn't successful, that I don't disagree with.  

 

But they clearly didn't have similar results.

 

 

Edited by able, 20 February 2019 - 09:30 AM.

[stefan_001]

@able you are comparing studies which didn't have the identical test setups. That is why I posted the link, the researchers used both NR and NMN in the same model and conditions and did not find a difference.

[able]

Ah, ok.  I hadn't seen that one before.  It does look like they both had similar benefit in that form of ataxia.

 

Did you happen to notice NMN was slightly more effective at increasing NAD+ levels and performance in the physical performance tests?

 

 

 

 

Edited by able, 20 February 2019 - 10:43 AM.

[MikeDC]

David Sinclair "NR is converted to NMN and then NMN is immediately converted to NAD" on the Peter Attia Podcast, see https://peterattiamd.../davidsinclair/ at around the 1hr09min mark.

This is true after NR enters cells. But NMN needs to convert to NR outside cells to enter cell.

[MikeDC]

Ah, ok. I hadn't seen that one before. It does look like they both had similar benefit in that form of ataxia.

Did you happen to notice NMN was slightly more effective at increasing NAD+ levels and performance in the physical performance tests?

Mice were fed 12mM NR or NMN solution. NMN has a molar weight of 334 and NR 255. So weight wise, 31% more NMN were used than NR. If supplements are sold based moles, NMN has a slight advantage. If supplements are sold based on weight (mg), NR has a big advantage.

Edited by MikeDC, 20 February 2019 - 12:31 PM.

[MikeDC]

All our comparisons of NR and NMN assumed that they both have perfect bioavailability and intact NR and NMN can enter blood stream. In reality, the majority of NR and NMN are hydrolized into NAM before entering liver. So oral NR and NMN should have similar results with NMN less efficient due to higher molecular weight. The advantages of NR over NMN increases as bioavailability increases because a majority of NMN needs to covert to NR first before entering cells. Sublingual NR should be better than NMN if it actually works. We have not seen any study of sublingual use of NR or NMN.