Published on: 2020-07-24

Longevity interventions when young

I should start this post by saying that I am a layman when it comes to everything I'm going to be discussing here.

However, I am left in an unfortunate position where all of the focus for applying healthspan-extending interventions in humans is focused on older individuals. This is understandable under "do no harm" medical ethics, the older you are the better your risk vs reward probabilities are.

But when we take a more detached view, young people are the obvious best candidates to fight aging in. Aging needn't be reverse in young people, only stalled.

Thus I had to do a bit of reading up on the subject. As I've been doing that, I realize I've come up with a plan plus some avenues for future investigation (i.e. self experimentation). This article is a distillation of the plan and the thought process that lead me to it, but I am leaving out a lot of details for the sake of brevity. The conclusion is a bit underwhelming, but I at least try to explore relevant areas, instead of wasting time on "longevity lifestyle" type topics.

I A quick overview of the problem and target

I will go ahead and assume that you are familiar with various theories around aging. For the purpose of this article, I am going to assume that the epigenetic theory of aging as propose by Guarente, Horvath, David Sinclaire, et al. For more information on this theory a good starting point is the Wikipedia article on the epigenetic clock [1], a good followup being a paper by Horvath himself [2] and a good reference to carry while reading is [3].

The other theory I'm taking into account here is the mitochondrial theory of aging [4], both in the form where it speculates that reactive oxygen could cause genetic & structural damage to the cell and in the form where it speculates mitochondria genetic integrity degrades faster than that of the rest of human cells.

In short, aging is an interconnected process that goes something like:

Cell DNA loses structural integrity with continued existence (e.g. when the DNA is read) and with each replication. Over dozens of years, this leads to many/most cells being dysfunctional from an epigenetic standpoint. I.e. not having the correct genes activate/deactivated/promoted in order to express the optimal quantities of proteins that allow them to fulfill their role.

Cells suffer genetic and epigenetic damage due to external causes such as radiation damage, physical damage, chemical damage, infection with a virus/bacteria... etc

The mechanisms for repairing and staving off genetic and epigenetic damage seem to get worst as we age and they get worst in cells that have suffered more genetic and epigenetic damage.

The mechanisms internal to the cell for destroying cells with too much genetic or epigenetic damage can malfunction due to... genetic and epigenetic damage => senescence or cancer.

The mechanisms internal to the organism for destroying cells with too much genetic or epigenetic damage (e.g. the immune system) lose potency with age. Due to genetic and epigenetic damage.

This damage accumulates, partially due to external factors and mostly due to the ways humans are "designed". The accumulation is "exponential", most types of damage cause positive feedback loops that make other types of damage easier.

It should be noted though, that when I say "damage" here I mean that from my selfish point of view, not from a natural selection point of view.

Tissue belonging to the immune system being replaced by adipose tissue is "damage" from an individual's point of view, but it's a "feature" working as intended from natural selection's perspective.

This is not a complete picture of the situation, not even from my layman's perspective, but I think it's a good practical synopsis we can start from.

When do we want to stop these aging mechanisms? If we could have a "static" snapshot of our body we are born anew into each day, how old should it be?

Looking at mortality per age demographic in the UK [5], a rough answer is somewhere around 12, but anything up to 20 and maybe even 30 should do just fine.

How do we go about doing this?

II Figuring out the actionable issues

It's very simple to point at the "cellular" level causes as "genetic and epigenetic damage", but figuring out the mechanisms that can stop this doesn't seem like a solved problem

We can say things like:

mTOR inhibition (which inhibits cell division, among other things [6]) seems to increase the lifespan.

Increased sirtuin expression and NAD+ level seems to sometimes help stave off some of the genetic & epigenetic damage.

Telomere length is a decent essay but doesn't hold much water as an actionable-upon target.

Proteins that allow for epigenetic de-aging exist and seem to work in vitro.

etc

But there's no complete picture one can plug some numbers into to get an intervention plan

Epigenetic aging (and thus it's reversal) can be traced down to the expression of certain genes, e.g. the Yamanaka factors [7], which are used to create pluripotent stem cells from "normal" cell (i.e. reverse the epigenetic "age" of a cell [8,9]). An easier to understand view on the topic, though one which to me seems to make some mistakes in the way it simplifies, is the book Lifespan: Why We Age―and Why We Don't Have To [10].

Even more so, reversing the epigenetic age of cells is likely a process that will inadvertently promote the creation of new pluripotent stem cells, depending on the intervention, so it can also serve to help "replace" cells which are to badly damaged with "young" ones. [citation needed]

Genetic damage, assuming it sticks, is permanent. However, most genetic damage is either disadvantageous (=> cell line dies out) or fatal (=> same thing, but faster) and when it isn't, it's usually harmless. In situations where all 3 aren't true, we have something that might turn cancerous or otherwise dangerous, which is why we have the immune system.

Speaking of which, let's turn to an overview of the "macro" causes/symptoms of aging.

The first thing that concerns me is brain function and associate motor skills. But Warner Schaie [11] says I have basically nothing to worry about just yet:

Same goes with motor control [12], it seems that up until my 30s I can pretty much ignore both as long as I apply the "use it or lose it rule", which is part of a life well-lived anyway, so it's not that relevant.

As for the rest of my body, most of it is either rather sturdy or somewhat redundant. For example, joint issues seem rather painful, but fixating on preventing them would just have me circle back to the cellular causes.

The things which seem to stand out most as having potential for being viewed as "causal" are the endocrine and lymphatic systems. I think there could be some interesting solutions that pertain to the endocrine system directly, but besides HRT (designed for old people) I haven't been able to find any. So my focus will remain on the lymphatic system, specifically the thymus.

It's actually a bit hard to find a definitive analysis on the topic, but, basically, all the primary literature will suggest the same thing: The thymus and various markers we associate with its function shrink with age starting somewhere in our teen years if not before [13, 14]. This shrinking isn't necessarily the case for newborns (e.g. see [15]) and the thymus can regrow to some extent.

This is obviously a very bad thing and seems to be strongly correlated with everything from infectious disease to cancer in all tissue types [16]. Going back to our causes of aging, the reasons for this become obvious.

Which is not to say we'd want to have the thymus of a 2-year-old at 20, there's a reason the thymus shrinks. The more pathogens we get exposed to and the more our immune system gets accustomed to various proteins our own mutated cells might be predisposed to accumulate (citation needed), the less need of new immune memory cells we have.

Immune cells are expensive to maintain and known to sometimes accidentally damage or horribly and swiftly murder their host [17]. If you've ever taken an antiinflammatory drug, that's a sign you might at least in part agree with this sentiment.

Regardless, it seems practical to err on the side of "more" for anyone beyond their teen years.

So, as it stands, my position is something like this:

I am constantly suffering genetic and epigenetic damage, both in my cells and my mitochondria. This damage will get exponentially worst as I age since it comes with positive feedback loops attached

The one organ/system that is most essential at combating this damage, as well as combating external threats to my body, is constantly shrinking.

III The standard nonsense

Here is where I see most longevity intervention articles fail, in failing to focus on any real solutions because they are risky and uncertain. But focusing on lifestyle advice is pointless because it's a solved problem. Most people don't implement the solutions, but that's mainly a question of willpower. It's ultimately something that the individual must shape for themselves in a way that works for them.

The short-review of this section, if I must give one, is:

Don't eat anything with added fructose, glucose, sucrose or dextrose or anything breed to contain large quantities of those.

Don't eat anything with traces of hydrogenated fats, processed meat added fiber.

Keep in mind you can react badly to certain carbohydrate-binding plant proteins, figure out if and what they are.

There's an argument to be made that excessive consumption of omega 6 is bad, and either way you wouldn't want to see where that added soy/sunflower/rapeseed oil in the can came from, so maybe just avoid those unless you really like them.

Take a bunch of supplements depending on what you think your diet and environment might be missing, measure their effect (via daily blood draws looking at specific markers, not via placebo-ing yourself). Personally, I do a very small dose of D3, 100mcg MK7, 100mg MgCitrate, and a pinch of dry spirulina. YMMV, go by trial and error.

Exercise with a focus on staying mobile but without damaging your spine and joints, if you don't know how, visit your local science-bro for lifting, eastern-spiritual yippie for yoga or kinesiotherapy for pilates. Also, if you can mix exercise and social all the better. I have my sweet spot at inconsistent night runs, morning mobility exercises, 3x/week light weight lifting, plus climbing, swimming, and hiking whenever I feel like it.

Sleep, don't stress out too much. Don't smoke, don't drink alcohol, test your drugs, don't stick sharp objects down your throat, don't surround yourself with mercury vapor, avoid ingesting copious amounts of cyanide, limit your amount of free climbing and your visit to warzones, live in an environment containing oxygen... etc

Ok, I'm done with this bit.

The gist of it is that a "healthy lifestyle" is obviously a prerequisite for everything here. But a healthy lifestyle can be many things and it boils down to individual tradeoffs.

IV Combating cellular aging with small molecules

Sadly enough, it seems that one way or another most "longevity-promoting" small molecules have a roundabout way of being complex-1 inhibitors, AMPK activators, CAMP inhibitors... etc.

Things which are certainly more than helpful in greatly extending the lifespan of a metabolically compromised individual, but have little indication of doing anything for those that are already "healthy".

One of the caveats with cellular aging is that a lot of drugs are tested on unhealthy people. Someone with metabolic diabetes or NAFLD is not an accurate template for normal cellular function (see section III for not getting those).

This is one of the reasons for which I am unsure of the bellow substances even when they seem to show some efficacy in humans and I don't even bother to discuss other popular ones at all (e.g. metformin).

Most of what we'll be looking at are animal studies in rats and mice. This is because they are vaguely similar to humans (as opposed to E. coli or yeast) and have short enough lifespans for experiments to be able to investigate it.

How do we even being to translate mice and rat dosages into human dosages? Long, complex, and case-specific story. Can we get an approximation? Kind of, according to [18] we can boil it down to:

dosage_human = dosage_{x}/ (avg_{x}_weight/avg_human_weight)^0.33

Assuming that weight is 0.02kg for your average lab mice => dosage_human=dosage_mouse*0.07

Assuming that weight is 0.02kg for your average lab rat => dosage_human=dosage_mouse*0.15

This is a very loose approximation, but the formulas in the papers are gross estimations of body weight vs surface mass scaling anyway. So what's another +/-25% dosage error to add to the pile?

If something works for you, you should determine the exact dosage by trial and error using relevant markers. If you don't have any, assume placebo and err on the side of caution by taking less if you still want to take something due to the theoretical backing.

A good introductory reading if some of the things in this chapter seem to shallowly explained compared to the level of the references would be [28].

Let's start the beginning:

Rapamycin

Rapamycin is an mTOR inhibitor. I do not understand how rapamycin functions, because I don't understand how mTOR functions, and I'm not sure anyone does (citation needed).

In particular, as a core component of both complexes, mTOR functions as a serine/threonine protein kinase that regulates cell growth, cell proliferation, cell motility, cell survival, protein synthesis, autophagy, and transcription. As a core component of mTORC2, mTOR also functions as a tyrosine protein kinase that promotes the activation of insulin receptors and insulin-like growth factor 1 receptors. mTORC2 has also been implicated in the control and maintenance of the actin cytoskeleton

[19]

In other words, mTOR does... everything. This enzyme seems to literally be implicated in all processes at the core of cellular life and reproduction.

For some reason, rapamycin seems to be quite deadly to fungi and the mTOR inhibition seems to be particularly useful in generating an immunosuppressant effect in humans.

The studies that do look at its effects on lifespan though, seem promising based on experiments in mice, the most informative of which I find to be: [20, 21, 22]. The kind of increases observed in certain strains seem comparable to those of severe caloric restriction.

This is by far the most efficacious but also the scariest molecule on this list. As far as I understand its effects upon your body would be similar to fasting and thus not entirely pleasant. The accentuated immunosuppressive effects, in particular, give me pause.

The biggest advocate for longevity usage, that I've followed the works of, is Peter Attia. You can find all his material on the topic here [23] and I'd particularly suggest this [24] podcast discussing it with David Sabatini. They are less rigorous than an article, but it's fairly easy to skip over the chaff and get into the relevant bits. They are also complemented by generous references to the things discussed if you want to dig further.

On the whole, there are too many confounders here for me:

Benefits don't seem too cumulative with fasting, which is already something on the list (see below)

It's effects upon metabolic processes which could lead to the longevity effect only taking place in mice on a very poor diet (doubtful, since the effect is so large)

That in itself would be fine, were it a mainly harmless substance, but it seems to bring with it a series of potential side effects. It's the kind of thing I'd consider taking in cycles to compliment fasting when I'm older, barring a better solution, but not right now.

Resveratrol

Initially, Resveratrol seemed promising because it was an antioxidant (benefits according to the mitochondrial/ROS theory of aging) and it seemed to have something to do with the function of these seemingly important DNA repairing & structure maintaining Sir2 proteins.

The first wave of research was focused on the idea that Resveratrol was a caloric restriction mimic, it's lifespan extension properties were most apparent in metabolically damaged mice and rats. Lean mice and rats that benefited from CR didn't seem to derive lifespan extension from resveratrol, though some other benefits were observed in certain studies [25].

Human trials are done, some benefits were observed with dosage around between 1 and 5 g/day (mainly around 1-2), it seems perfectly safe. But the benefits aren't groundbreaking and are more obvious in metabolically compromised individuals [26]. Then again, "causes harm" studies for supplements aren't exactly a hotly founded topic, so take with a grain of salt.

The last interesting and more recent discovery about it is that it seems to promote levels of key enzymes that help with the synthesis of NAD+ [27].

Note: pterostilbene seems almost analogous in function to resveratrol. For some reason, some drug cocktails sold as longevity enhancers contain it instead of resveratrol. I chose to focus on resveratrol since it seems the more well studied of the two.

This gets more promising when we get into our next two small molecules:

Nicotinamide mononucleotide (NMN)

Alright, here we get into the sirtuins. Which I don't have time to go into nor am a qualified person to speak about. The gist of it boils down to:

Various Sir2 genes are a critical part of various DNA repair mechanisms and for some reason. They are also histone deacetylase, which means they serve a role in maintaining the structural integrity of DNA and for some reason, there seems to be a particularly large effect size when modulating their expression compared to other HDACs.

Intra-cellular and intra-nuclear levels of NAD+ seem to be critical to their function with the relationship being along the lines of "the more the better" seems to be the silent consensus. Declining NAD+ levels seems like a hallmark of aging [29].

But the story that that same study paints about the NAD+ level & SIR2 (Sirt1 specifically) activation link is a bit more complex than "More NAD+ => more Sirt1/7 activity".

Also, maybe I am painting a bit too rosy of a picture here. I can't find the study at the moment, but see links between elevated NAD+ and infertility and NAD+ in the bloodstream is a potential signaling molecule for an immune reaction (since free NAD+ in the blood would usually indicate a large number of cells undergoing apoptosis) [citations needed]

There seems to be a straight forward path between NMN and NAD+ assuming:

a) NMN can get into the bloodstream

b) NMN or one of its metabolites that can turn into NAD+ can get into the cell.

So take resveratrol and take NMN and you've got Sir2 activation and you're actively working towards solving the problem of cellular aging, right?

Sigh

There are no half-decent reviews of the literature here and I am really lazy so I just commissioned a "literature review", by which I mean to say I asked a guy to find all half-decent studies and compile dosage + whether it was in vitro or in vivo + organism + observed effect + administration method + other relevant notes. So most of the digging here I'm basing off [30] + some skimming I did through the more relevant articles here (in mice + oral administration)

Effects that could be plausibly associated with longevity are found, but no studies look at the actual lifespan of NMN feed mice or rats. Some are just in vitro studies, others inject the NMN (which for various reasons you might not want to do [citation needed]). The ones where it's administered orally use dosages ranging from 100 to 500 mg/kg daily, which translates to 420-2100mg for a human weighing 60kg based on our rough estimation.

There are some promising results, but those are mainly in terms of restoring function to old mice rather than preserving it in young mice.

The problem of absorption is a live one, i.e. how well is NMN absorbed through the human gut. The one human trial we have [31] failed to look at this, though they did get some circumstantial evidence regarding increased levels of NMN metabolites... but that's not exactly ideal.

The alternative to oral is sublingual, but all the marketing push and studies behind that approach seem to be done by a single company [32] with a very tiny research team and no real track record to speak of (The FDA is apparently harassing them, but nowadays that might count as a seal of quality rather than an indication that they are doing something wrong.)

Even if the absorption problem was solved, point b) and the question of NAD+ efficacy still remain. But our current theoretical framework, backed up by some in vitro and mouse studies seems to indicate the answer for b) is yes and the answer for NAD+ efficacy is "some considerable magnitude positive effects in the areas monitored".

This is not very promising. Enter:

Nicotinamide riboside

The idea with this one is pretty similar to NMN, I won't enter into the details (seem to boil down to better gut absorption profile but more of it being metabolized in the liver instead of reaching other tissues).

The studies are a whole other world, after the NMN literature seeing a study named: "Repeat dose NRPT (nicotinamide riboside and pterostilbene) increases NAD+ levels in humans safely and sustainably: a randomized, double-blind, placebo-controlled study" is like a breath of fresh air.

And there's more of them! A total of 3 relatively well-conducted human studies looking at safety, NAD+ levels, and a few other additional markers all with encouraging conclusions [33, 34, 35].

There's no a lot to for me to harp on about here. Assuming that the NMN story seems plausible to you, NR is the same thing but with more of the absorption happening in the liver and with human trails to back up the animal results. Granted, none of the human trails are long enough to see anything relevant to us assuming we don't believe the NAD+ -> longevity link.

Some mice studies show no effect on lifespan (but some effect on "healthspan") [36] and some show a minor effect on lifespan [37]. Either way, these numbers are nothing to write home about, we're not getting any closer to immortal mice here... we're nowhere near close to the effects of caloric restriction.

For a more detailed review of NR, especially if you are considering taking it, I suggest [38]. The study also goes into the details of how increased NAD+ level can actually be damaging to lifespan and the precursor seems to matter a lot. But, same as before, loads of yeast and mice and not a lot of humans.

Thus I will end the journey through the small molecules I have considered and found worth discussing. I am confident that a combination of NMN, NR, and resveratrol would be the way to go for me, were I an old obese rat with a habit for high-fat+high-glucose chow. I'm still unsure how well this translates for a healthy 24yo human, but err on the side of "some positive effect with a relatively negligible risk profile".

V Combating cellular aging with other interventions

This chapter will be a lot shorter and less practical stuff may come out of it for all but the most adventurous of you.

The interventions I want to look at are fasting/CR and gene therapy.

Starting with fasting, the theory sounds quite simple:

Humans have been doing this for a lot of time to promote longevity and some form of time-restricted feeding and/or caloric restriction seems to be a blue zone staple. The rat studies are very promising, [39] find lifespan almost doubling compared to the very short-lived control. Even if one could argue the control here was surprisingly short-lived, there's still a ~20% improvement in median lifespan over that of the type of rat used in the experiment, see [40] for details on the rat specie's normal lifespan.

But that's just a cherry-picked example with stunning result, however less stunning but still undoubtedly positive and significant results are found in other studies [e.g. 41].

In addition to that, caloric restriction is a well-known lifespan extension technique and we could see how many of its potential benefits overlap with fasting.

There are known benefits for stopping nutrient intake for a prolonged amount of time at a cellular level. First, there is a "survival of the fittest" process among cells, mitochondria, and organelles.

Mitochondria that are unable to efficiently produce ATP are "starved out". With ever-increasing selection for mitochondria that can efficiently use BHB, ketones, and fat the longer the fast goes on. This seems to be partially aligned with the reason metformin seems to help with lifespan increase (if we think of it as a complex 1 inhibitor).

Cells that have damage to their DNA and organelles might often function "less efficiently", but this is not enough for them to die in normal nutrient conditions, however, when starved of nutrients this mechanism may be triggered.

The immune system might be more active in collecting senescent cells (those that have lost the required machinery to undergo apoptosis) and more active overall in finding cells that it can signal to commit apoptosis (e.g. infected cells or cells with mutations).

Internally, cells will also clear out damage organelles, and other (hopefully) redundant proteins floating around via autophagy (basically increased production & activity of autophagosomes [43]) to sustain their function.

There's obviously a component of mTOR inhibitions as cells divide less but seemingly without the same effect upon the overall efficacy of the immune system.

Finally, there's an increase in hGH, which amongst other things promotes thymic regeneration and pluripotent stem cell creation (more on that later).

[citations needed for all the claims above, I wasn't maintaining my wiki properly when I was looking into this, sorry]

The question remains: What fasting method to use? The answer to that seemed impossible to give before, but I think I've found and inadve[citation needed]rtent solution by looking into Thymic regeneration (see next chapter).

Next, some cofactors promote the creation of pluripotent stem cells and the overall epigenetic "restoration" of cells. This is a good thing until cells become too undifferentiated and can no longer function and/or end up mutating to cause cancer.

Honestly, while this is an interesting avenue, the research on this is still scarce and it seems to me like to high risk of a solution to try. Feel free to pick up google scholar and dig through some studies if you wish.

The base idea is simple, use a gene insertion vector to add genes for Yamanaka factors to some or all tissues. Code the plasmid to be activated via a relatively harmless molecule when ingested, now you've temporarily got an epigenetic de-aging mechanism you can trigger at will with a pill.

In practice, again, what you probably end up here with is the deregulation of your entire metabolism and/or cancer unless you are careful. This is a nice solution in that it seems like it should work for older individuals and doesn't necessarily favor the young, so I'll wait until I'm older and more research is out.

VI Thymus regeneration

Based on effects in humans and my overall knowledge on the topic I think it makes sense to split this section into two:

1. Thymus regeneration via hGH

hGH encourage c-Myc expression, this makes it an interesting combination between cancerous and potentially able to revert epigenetic aging (c-Myc is one of the Yamanaka factors).

It's present in tall people and men, tall people and men die young. It's less present in short people and women, short people and women live longer. But this might all be due to other things associate with those conditions,e.g. IGFs overexpression. Indeed, if you want to enter the 'longest-lived lab animal' competition the way to do it is to knock out the IGF receptor genes.

A new study came out a few months ago and it showcased it's hGH based method as being able to help with thymus regeneration and revert epigenetic aging as measured by the Horvath clock [44].

Researchers in [45] told people to inject themselves with rhGH and take 500mg metformin and 50mg DHEA, also 3000 IU D3 and 50mg zinc. The people did this for over 1 year.

They then noticed the reversal of the Horvath clock by 2.5 years and a relatively impressive amount of thymic regeneration as well as bone marrow regeneration.

epigenetic age approximately 1.5 years less than baseline after 1 year of treatment (−2.5‐year change compared to no treatment at the end of the study).

Those substances are rather cheap and easy to get. If you are following a proper diet all but the metformin are probably not needed. If you are fasting metformin might not be needed either (also, see above, if you are taking resveratrol). The problem is that to get hGH, as a young person, you'd need a doctor that trusts you a lot or you'd need to procure it outside of Europe and the US.

You can get rhGH relatively safely in Russia, Thailand, and (if you have enough money) the UAE. You can also order from the shadier parts of the controlled-net, or a TOR website, or get it from the physical black market (do they exist anymore?), but unless you also pay for a CoA, I wouldn't trust the quality.

Also, even at a low p-value, getting shot by a cop is a really bad move from a longevity perspective.

Furthermore, injecting hormones into yourself is usually not a thing you should do willy nilly. Your endocrine system is very reactive to current hormone levels. Due to the way hGH levels are controlled (via the level of GHRH), this might not be as true for it as it is for e.g. testosterone. Still, it's a gambit that might make you forever "addicted" to exogenous hGH for your body's well functioning.

Happily enough, this is the last and most relevant place where I will bring up fasting, for it can solve this problem for us.

First, we need to figure out how much rhGH the participants were taking, the study is vague about this but I believe I can get an approximate number here.

The study describes the rhGH dosing as:

rhGH (Omnitrope, Sandoz) was provided to trial volunteers and was self‐administered 3–4 times per week, depending on side effects, at bedtime along with other study medications.

The only information we get is:

During the first week of the trial, rhGH alone (0.015 mg/kg) was administered to obtain an initial insulin response

Let's look at the guidelines for Omnitrope [45]:

Based on the weight-based dosing utilized in clinical stu ... dosage at the start of therapy is not more than 0.04 mg/kg/week .... increased at 4- to 8-week intervals according to individual patient requirements to not more than 0.08 mg/kg/week.

So, I guess we could assume the dosage was somewhere between, say 0.02 mg/kg/week and 0.08 mg/kg per week ?

There's also the problem of absorption

[46, 47]. As in, how much is being absorbed in the blood and how quickly. But the studies here are all in sick individuals and I was honestly unable to get anything cohesive from them. Absorption seems close to ~100%, so I'm just going to ignore the time element for now.

So now let's move on to the rigorous literature on fasting and hGH:

I see [48] getting cited a lot to say that long-term fasting increase hGH. I've seen it cited in other studies as well as on Healthline, WebMD, and other pop-medicine websites.

But it's a confounded mess, they test hGH levels very rarely, it mixes it's subject with literature references and it's an n=1 study, on a middle-aged monk...

The next study I found is [49], a larger sample, but it looks at a very quick 36 hours fast and uses obese people, so I'm not sure how much we want to go by the data here.

The other commonly cited study I could find is [50], but in this case, the participants are actually injected with GHRH after 20 hours of being observed in a fasted state, so for our purposes this becomes irrelevant.

When I search for information on the topic I get articles like [51], that cite [50] and seem to miss the memo about the GHGH injection. Others cite [48] and seem to confound between the actual study they ran and the extra literature analysis presented in it that is not directly linked to other fasting human hGH studies.

A band of thankless heroes come to the rescue: MARK L. HARTMAN, JOHANNES D. VELDHUIS, MICHAEL L. JOHNSON, MARY M. LEE, K. G. M. M. ALBERTI, EUGENE SAMOJLIK, AND MICHAEL 0. THORNER.

These guys seem to have produced the only existing human fasting hGH study [52] that's relevant for healthy humans. It has:

9 subjects

subjects not selected out of an insane monastic population

subjects healthy men between ages 24 and 28

subjects BMI between 21 and 25

subjects not injected with hGH production boosting hormone

subjects had a cannula inserted and blood samples were collected every 5 minutes

subjects were constantly monitored in the lab

subjects were fed for one day with a controlled diet in the lab

This is amazing. Why is nobody citing this one instead of those other 3? I'm starting to feel like a lot of the literature on this subject is very bad. But regardless, this study still stands out as excellent for our purposes with no obvious flaws.

The 2-day fast resulted in a more than 3-fold increase in 24-h mean serum GH concentrations (2.0 +/- 0.29 vs. 6.7 +/- 1.1 μg/L, P = 0.0004). The percent of samples with undetectable GH concentrations was 29 +/- 8.5% (range 0-74%) on the control day, and 3.0 +/- 2.0% (range 0-18%) on the fasting day (P = 0.01).

and

Twenty-four-hour endogenous GH production rates were increased 5-fold by 2 days of fasting

You can see an individual case study and more data in the study, but for now, I will focus on this idea that, if you don't eat for ~32 hours and keep fasting for the next 24 hours, your hGH levels in the blood will be increased to a bit over 3 times the normal amount, this seems to be very consistent among subjects. Also, secretion increase by 5 times the normal amount, which I assume means more hGH gets taken up into various tissues (?).

The 3x and 5x increase are good guidelines, but I still need to know my baseline. hGH secretion differs between people but not so much as with other hormones, I'll just go by what Wikipedia [53] says:

... healthy adults secrete GH at the rate of about 400 μg/day ...

So 3x that amount would be an extra +800 ug hGH as the result of a 56 hour fast. But, if we assume the 5x number is what we care about then that means +1600 ug.

A 56-hour fasting window is unideal, it's too long. Single-day fasts (i.e. one full day + night without eating) usually last for 48hours - (duration of feeding window). So, for example, if your feeding window is ~4 hours like mine, that means 44hours.

To add to that, hGH works in bursts, so it's not like we can get half the amount in the last 24 hours if we only fast for the first 12 of those. The bursts are also correlated with sleep, the study isn't very clear about this, but it seems like subjects were allowed to go to sleep at 10 PM and there's indeed a significant spike associated with that, though not nearly as significant as in a fed state, where a short period in their sleep might be when they produce over 75% of their hGH.

This could be grossly estimated into saying that a 2-night fast (i.e. sleeping 2 night without having eaten the day before) could easily get us 1,600ug hGH, but probably much higher, since again, the first 32 hours count for 0, but I assume that first night also had some increased secretion.

Again, keep in mind, this is a "stupid" estimation for the "average" human that produces ~400ug hGH a day.

Assuming that same "average" human weights ~60kg that means the thymic regeneration study administered 1200ug-4800ug per week. So given that we're probably missing out on some hGH from the first 32 hours, I think it's a good first guess to estimate that this sort of 56 hour fast could get you into the low-mid range of hGH increase that showcase thymus regeneration in the aforementioned study.

But at the end of the day, this is irrelevant, we need to actually measure our hGH when fed and fasted to get some real numbers here. But we'll come back to that problem later (and sadly enough, won't solve it)

If you like life in the fast lane

For the other methods of Thymus regeneration, I think [54] is a perfect reference, while I read some of the things quoted here + some more I don't believe I understand the subject well enough to be quoting most papers here, so for most of my claims, go to that study and dig for yourself if interested.

1. Inject yourself with interleukins (Id gamble on IK-7 but YMMV, test and monitor if you want to try this).

Pros: Human trials, relatively cheap, can be done with a subcutaneous pump, maybe you can avoid getting symptoms if you do this while in an environment with a high risk of catching a cold (e.g. airport)

Cons: Some applied medical knowledge required for administration, short shelf life, no guarantee this works long terms and common sense tells us it shouldn't (otherwise we'd notice a lack of thymic degeneration is people with certain autoimmune diseases), injecting yourself with inflammatory proteins could make your feel unpleasant and also have a lot of side effects ranging from triggering an autoimmune condition to internal damage to a quick and very painful death.

2. Periodically inject yourself with a plasmid carried by a viral vector that can then be used to increase expression of FOXN1 at will (e.g. by taking a harmless antibiotic or some other drug that triggers the production) [55] have an experiment with this in mice and their paper also serves as a good review of the previous literature on and competing viewpoints on this topic.

Pros: Spectacular effects if you are a lab mouse.

Cons: Requires you to order a specific plasmid, a quick search on Addgene indicates no suitable one so you probably have to also design it and or search really hard for one that works and pray that you understood it correctly. Overexpressing proteins that are heavily related to core intercellular signaling mechanisms in humans may lead to anything, as risky as it gets. Other researchers that tried it found less spectacular effects (see Discussion section of the paper)

3. SSIs, sex steroid inhibition is potentially the best-studied method to induce thymic regeneration and seems to work across age groups (if you are a mouse).

Pros: Cheap as chips, loads of human trials for other purposes so side-effects and safety profile, while unideal, are well known, moderately positive effect.

Cons: Maybe not as easy to get as you'd expect, messing up with hormonal systems that (see above) are very reactive to changes, potential loss of energy. Confounded AF since they also act as de-facto statins.

**4. KGF, a growth factor that might promote thymus regeneration (similar to FOXN1), seem to be effective under a narrower range of conditions and have a smaller effect size BUT this might just be due to the fact that more trails have been done and thus our picture is more complete and down to earth than with FOXN1.**

Pros: An analog of KGF can be taken as the drug Palifermin which as undergone human clinical trials, although you probably won't find it in a standard drug store.

Cons: Side effects exist, although they aren't the worst. Lackluster evidence of significant thymus regeneration outside of abnormal conditions (e.g. when exposed to a large dose of radiation).

5. (Not in the paper) Bacillus Calmette–Guérin vaccine. Anecdotal evidence might indicate this could help a bit since it offers a bit cross-protection against various diseases [56] and is linked to an overall increase immune response. A study in newborns indicates the answer is no [57] , but newborns are weird. If it does work, the mechanism is likely similar to (1). If you like (1) in principle but it seems dangerous this might be a good middle ground (?).

Pros: Cheap, effectively no risk when compared to everything else discussed in this article.

Cons: Probably not very effective if at all.

6. (Not in the paper) Samumed seems to be developing various WNT pathway-related drugs that essentially work to (among other things) correct the malignant immune signaling mechanisms that appear with age (citation). Might be worth looking into some of their drugs since they should finish phase 3 fairly soon.

There an additional secondary source on the topic of thymus generation I should recommend [58], it's also somewhat easier to read , it proposes similar solutions with a few twists.

VII Measuring: A summary of the summary

Before we talk about an actual protocol we need to talk about measurements. If we don't have a success/failure state we can delude ourselves to believe everything is working even though nothing isn't.

It's also important to remember that if we use a proxy as a targe that proxy might become irrelevant. For example, if someone is diabetic we can probably use insulin response to a glucose challenge as a marker of epigenetic age, since curing his diabetes will probably improve that as they regain closer to normal function. If someone is perfectly normal, the response to a glucose challenge is noise.

If we use a battery of assays that directly measure n markers to indicate "immune system age" and optimize for those, we could be optimizing our immune system to stay in it's 20s, or more likely, just those n markers.

Same goes for IQ testing, use the same one each time and it should keep going up well into your 80s despite the thing you are trying to measure probably starting to degrade 50 years earlier.

I see three ways of avoiding this:

Having "train" assays and "test" assays. We optimize some drugs on the "train" assays and then validate the results on the "test" assays. Regularly changing assays. Whatever you are measuring to indicate immune system regeneration this year, switch it up next year. Use markers that are hard to optimize for and where "optimizing" should essentially be equivalent to solving the underlying problem. Thymus size and epigenetic clock are good examples here. Though ultimately no marker falls into this category fully, there's always room for overfitting a therapy.

Also, use things that you can measure all the time at almost 0 cost. Sleep monitoring and weight monitoring being the best examples. Takes ~30 seconds away from your day and it's amazing to paint a moving picture that has data for every single day of your life.

Continuous monitoring could also help, some preliminary devices exist for various markers in urine, you can also do things like blood glucose, heart rate, blood oxygen... etc. But the devices are noisy, expensive and messy for the most part. So I'm not sure if they are worth the effort.

Also, for the sake of all that's good in this world. Never use any sort of external """x-care""" products. Your skin and hair will be your first line of warning in many cases, especially when you might be particularly sick and thus too lazy/depressed to do proper testing without a push.

The things we probably really want to measure are:

Degree of genetic damage

Degree of epigenetic damage

Thymus size and activity patterns

Level of HGH and ideally Ghrelin and IGF

Intracellular autophagy

Number of senescent cells

Sadly enough, almost none of these are easy to measure and the more I think about it the more I realize measuring might require an article of its own.

Furthermore, what I list above is only the tip of the iceberg, measuring some of these realistically requires 20+ tests and there are other nice to haves that I'm not mentioning (various cancer markers, LP(a), levels of a few dozen environmental toxins that tend to accumulate faster than we can eliminate them, various steroids, various common disease with hard to detect symptoms... etc).

For now what I can say is:

Chest MRI can't hurt and is relatively inexpensive (e.g. a decent resolution chest MRI costs me ~150$). For more on using that to determine thymus size see [59].

Epigenetic/Horvath clock test every x-months can be good, but the resolution on that is not great, this will probably only pay dividends over a few years.

Glucose and Ketone monitoring is basically free, it's a very useful tool for deciding your diet.

Body composition scales are bad at absolute values but good at relative values and could be a useful addition.

You only need to get a full genome test once, it costs 500$-2000$ depending on the error range you are fine with. You might want to redo it in 5-10 years when you can get much smaller errors for the same price, but this one, while expensive, only need to be done once.

IQ is free and easy to measure and you need only do it once a month or so. ( I actually don't do this one, but for reasons related to not wanting to know my IQ and I'm really stupid for not doing so and should start doing it)

Also, having a bunch of "test" exercises to measure motor IQ, motility and strength might be a good idea. And, again, easy and free.

CTs can be useful but I will pass due to the radiation exposure. Also, MRIs might have some side effects, but I don't think they are worth worrying about unless your body contains significant amounts of metal in which case obviously don't.

For tracking the immune system's & thymus overall efficacy and MRI is not enough, but writing about the other assays means an article in of itself.

HGH and various other hormones are very to track unless you want to invest in nurse training and old hospital equipment. I'm still working on a strategy here and will expand more on what I have in the article dedicated to this.

Genetic damage, number of senescent cells, intracellular autophagy, and efficacy of various intercellular, and intracellular communication mechanisms are impossible as it stands. Arguably we can find some proxies, but again, this requires an article of its own and I'm not very sure of the ideas I have here yet.

VIII Do we have a protocol ?

So, what's the protocol that results from all of this?

Well, as you can see, the situation is bleak as fuck. Due to a hostile regulatory environment, human trials of anti-aging therapies are impossible and biohacking is no wide-spread enough nor done with enough rigor to gather data from individuals.

Trying things that work in mice on ourselves is risky and even if our assays indicate that they are working we might be causing secondary problems we only notice 5 or 10 years down the line unless we are lucky in what we measure.

Of what exists right now, most things that are promoted as "life-extending drugs" (e.g. metformin) are likely only life-extending in metabolically compromised people.

What I am doing right now myself is basically 2 rounds of supplements a day:

~700mg resveratrol, 300mg NR - just before my eating window begins or early in the morning

~700mg resveratrol, ~300mg NMN - right after my eating windows ends, or at the beginning of the evening

~200mg sublingual NMN right after that second dosage.

I like the evidence for NR more, but I think the potential is not that big, the potential with NMN seems better even though the evidence is poorer. I think taking a small dosage of both is ideal since the effects seem to be logarithmic, i.e. taking 2x mg is only 1.y times as good as taking x mg. So basically I might be getting "enough" of an effect even if one doesn't work. Also, different uptake profiles into various tissues will likely lead to a more even distribution this way.

I can't see any path for negative interactions between the two (especially taken far apart) I'm hopeful for better Sir2-related drugs being developed soon.

Dosage of NR I'm basing on the human trials, I'd consider taking ~400-500mg, but I noticed that most respectable sellers (Chromadex and Elysium) seem to favor either 250-300mg, so I'll go by their good judgment. [31] Indicates that it's well tolerated at that dosage, but whatever side effects might come up after 10 years nobody knows. I'm basing the NMN dosage on the fact that based on the mice trials effects seem apparent as low as 100mg/kg and didn't seem to increase that much with dosage (based on the hacky formula that translates to ~550mg for my body weight).

At the end of the day, you have to monitor various markers you care about to decide what works for you.

To that, I add a fasting regime which I've recently switched to: a single 60 to 66 hours fasts a week + a 4-hour eating windows with generous exceptions + a 7-day fast every 3 months (though this I can't justify other than saying something-something speculative autophagy benefits).

I'm working on a reliable way to monitor hGH so I can come up with some proper numbers for how long to fast, for now, the short eating windows + the 66 hours fast seem like erring on the safe side.

Even if I can't know how much hGH I am getting exactly, from the analysis above, it would seem a safe guess to assume it's equivalent to the low-mid ranges of the hGH dosages used by the above thymus regeneration study.

I can't do this year-round, the kind of caloric restriction this imposes would kill me. I have a "fasting month" and a feeding month, as a general rule of thumb. During the feeding month, I increase the eating window to 6-10 hours and only fast very occasionally.

This kind of "breaks" from the thymus study, but I assume that given 1 year of hGH oversupply has thymus restoring benefits, 1 month should be enough. This is purely anecdotal based on the scale I usually see with biological mechanisms. Seldom is there a drug that only takes effect after more than a few weeks. Also, my current monitoring seems to agree with me but it's too soon to speak.

But, of course, the benefits of the thymus study likely come from the demographic it was done in and won't be cumulative. You can't pump your body full of hGH, be it exogenous or endogenous and home your immune system won't age. This is a patch, something to hopefully slow things down and buy more time for better therapies, more self-experiments and more knowledge accumulation.

This should also serve to mimic some of the effects of taking rapamycin and some of the benefits of lifetime caloric restriction, I haven't talked about caloric restriction, recent evidence seems against [60] pure CR as a solution to aging. I'm unconvinced, but I don't think the effect is large enough, either way, to be worth worrying about and we get it via fasting anyway. If the subject interested you for some reason, this adversarial collaboration is a great starting point.

For the risks regrading NMN/Resveratrol/NR see the section above. Fasting has few risks as long as you're careful with your diet, but once you go calorically restricted getting back to "normal" eating levels without compromising your metabolism can be a long process. Also, if you are unable to control your diet you might be doing harm by switching between eating like a monk and eating like a Karen.

There's a caveat to that, in that, if you lapse into a "bad" diet for a few days or even week a week, which has happened to me twice, you can take metformin to offset some of the side effects (citation needed).

In the next 1 year I see to potential pathway I can go towards:

The "futurist" pathway, where I assume that research will keep moving at a snail's pace and my best bet is to delay with a high degree of safety and hope for an exponential increase in the future. In this scenario, I start cycling rapamycin. I sign up for cryonics, ideally at two different clinics and I start digging a lot more into gradual body & brain replacement. The "keep it in the pocket" pathway, where I decide the risk of thymic regeneration is small enough, and what I'm doing currently given a functional immune system, is enough to avoid significant epigenetic damage, so I go all out on whatever thymus regeneration therapies are available.

Currently, I lean towards approach number 2, ideally, the next article will include some more details about BCG and IL-7 since I will soon have results from an experiment with the former and am considering seeing the effects of relatively minuscule dosages of the later.

But my final decision will probably be made in 5-10 years based on how my Horvath clock is tracking.

Trying to lead a relatively healthy lifestyle in addition to this in terms of diet, exercise, sleep... etc is a must. I'm not the best at doing this, but I could be doing worst and all things considered, I've gotten much better over the last 3 years. Happily enough this seems to become easier with age.

Also, certain nootropics and other supplements can probably help, but their effects are small and thus only useful if cumulative, thus talking about them is better in the context of the measuring article.

This article is already way too long and I realized about halfway through I couldn't say all I wanted to say in it. I will probably follow it up with:

An article talking about measurements (I'll put a tentative date of 6 months on that one). An article talking about other promising interventions I haven't covered here but that I'm considering (I'll put a tentative date of 12 months on that one since by then I might be adding more interventions to my list). A more in-depth review of the literature on the problem of aging itself (I've got a draft sitting on my computer, but polishing it up is going to take a long time). An attempted analysis of what various other people are doing (this is mainly a data gathering problem).

IX MIstakes

In keeping this article short I paint a very simplistic picture of aging, while not "wrong" per se, it's not the one I'm acting from, it doesn't have enough resolution to explain my arguments in full. However, the reference provided should be enough to construct what I'd think is the "real" picture given current data.

I'm not backing up a bunch of claims, because I used to be very bad at indexing my references and I couldn't link the ideas to anything in my wiki. Some of the other claims without sources are deductive based on my simplistic understanding of biology. In principle, I don't think any of these claims are fundamental to the proactive part of what I'm doing & advising here though.

I'm as of yet very unfamiliar with the field as a whole and thus I can't really claim that what I present here is correct. Ideally, I would take the advice of someone that is and just lead you to him. Sadly enough, none that's an expert in the area seems to have tried to broach the subject, if you do know about someone tackling anti-aging interventions in the young I'm open to hearing about them.

I'm not sure my plan is actually half rational or just a rationalization of ideas that I've heard other people claim. I think it's rational, but it's also fairly close to what I've heard other people that got me interested in this area originally (e.g. David Sinclair, Peter Attia) are doing. So maybe this is just a rationalization of me aping other people.

I should probably be harping on the risks of NR and NMN more, both in the case where they are harmful like various other NAD+ precursors are and in the case where they work, but increasing levels of NAD+ when young could lead to downregulation of normal production mechanisms. I doubt the second hypothesis, but my argument for doubting it is not quite strong enough. I can't speak on the first one, except to say that I think the reason other NAD+ precursors were dangerous is mainly unrelated to their role as NAD+ precursors (citations needed for all of this... hence why I am bringing this up as a mistake)

I use a lot of primary sources when I could just be quoting secondary sources that take a much broader look. This is because whenever I pick up secondary sources I realize they more often than not suck (see hGH and fasting example), so I prefer to stick to a few primary sources I understand than be "lied" to by secondary sources that pretend to have reviewed the literature but are just parroting stuff.

I use "structural" and "epigenetic" in a potentially weird way. In that, I use "structural" to refer to any sort of structural DNA changes and "epigenetic" to refer to the "predefined" gene expression blocking/promoting pathways cells go through to reach their differentiate state that allows them to be part of whatever tissue they are part of. So e.g. I will say that a random histone getting attached by accident in a random place is "structural damage" or a double-strand break is "structural damage", but a gene being blocked in 90% of cells in a tissue, where we would rather have that gene be expressed but programmed death would rather have otherwise, is "epigenetic damage". I'm not sure these definitions make sense, they did help me wrap my head around a few concepts faster.

I am not a doctor, molecular biologist and I only really got interested in all of this as a side-side-hobby a year ago or so. My knowledge is still very superficial and you should probably use this article as inspiration for your own digging, rather than as an authoritative source. I know I'm repeating the beginning here, but I can't stress this point enough.

X References