New Database of Lifespan Trials

Human Ageing Genomic Resources announced last week their on-line database of animal studies that evaluated drugs and supplements for extended lifespan.  HAGR is a project of the University of Liverpool, spearheaded by João Pedro de Magalhaes, who has been an activist-scientist in aging research since his days as a grad student at Harvard.

The database is a great resource for researchers, and helps assure that we have no excuse for overlooking a substance or a perspective or a particular result.  Maintaining and updating it will continue to be an important and demanding project.

The full database covers 1316 studies, and I will review here just those on mice and rats.  My reason is that life extension in simpler animals turns out to be too easy.  There is much we can learn about universal biochemistry from studies in worms and flies, but most of the successes there fail when the (longer and costlier) studies are done in mammals.

Here is a spreadsheet extracting just the 93 studies on mice and rats.  You can view it online, and if you download it or copy it into your own GoogleDrive account, you can sort and edit and re-arrange it at will.


Old News

Rapamycin: Has the most studies and the best data.  Clearly works, but has side effects and it is not yet clear if it is appropriate for general use.  Make your own decision.  [read more]

Metformin: We have extensive experience with humans, and clear indications that it lowers cancer rates and ACM*, but there are dangers and side-effects. [read more]

Melatonin: Good evidence for modest life extension in rodents. For some people, it’s also a good night’s sleep; for others it can lead to grogginess or depression.

Aspirin:  The best evidence for lower cancer and ACM* is in humans.  Most people can tolerate a daily mini-aspirin without stomach complications.  

Epithalamin (and other short peptides):  This is work by Anisimov in St Petersburg, and it is so promising that I can’t understand why it isn’t being replicated all over the world. [read more]

Deprenyl:  Old studies, but they show consistent, if modest life extension.  It affects CNS in ways that you might feel, might like or might not.  [read more]

Vitamin E:  This is just one study, dosage equivalent to hundreds of pills a day, mice kept in shivering cold conditions.  [ref]  In a large human study, antioxidant vitamins increased mortality. [ref]

Acarbose: A diabetes drug that blocks the digestion of carbohydrates.  Side effects and toxicity make it less promising than metformin as a general recommendation.  [drug info]

C60 Fullerene:  Just one study in 6 rats, with spectacular results.  Replication has failed [private communication from Anton Kulaga].  Nevertheless, there are thousands of people experimenting on themselves. [read more]

Curcumin: There are major questions about absorption and dosage, but no question that anti-inflammatories are a good general strategy, and curcumin is a good anti-inflammatory. [read more]

Green tea:  Small but consistent life extension from polyphenols extracted from tea.  From a number of high-profile experimentalists, 2013.

Resveratrol: Works great in simpler animals, including some vertebrates, but in mammals life extension has been limited to overweight mice on a high-fat diet. [read more]


The New Part

BHT:  This is an anti-oxidant and chelating agent, which means that it is attracted to metal ions, it pulls them out of circulation and takes them out of commission.  This sounds good when it’s removing mercury or lead, but less good when it’s removing iron and dangerous if it’s removing zinc or other essential trace minerals.  BHT has long been used as a food packaging additive to preserve freshness, and it is still avoided by natural foods types. This Russian study [2003] found 17% life extension in mice. 

Creatine:  Used by body-builders, it encourages muscle growth by blocking myostatin.  It also increases nerve growth, and slows shrinking of the brain.  In one promising mouse study [2008], average lifespan increased 9%.

Icariin: This is an active ingredient in the traditional Chinese herb which in the West is known as Horny Goat Weed.  One mouse study, 6% increase in lifespan.

VI-28: Another Chinese herb.  Just one study, up to 14% increase.

Royal Jelly:  Queen bees are genetically identical to worker bees, yet they live 100 times longer.  Is it the royal jelly they are fed?  One mouse study [2003] showed a 25% increase in mean lifespan, but no increase in max lifespan.

N-Acetyl Cysteine:  Glutathione is an antioxidant associated with mitochondria.  Unquestionably, glutathione is a good thing.  Too bad we can’t just eat it.  The next best thing is to take the precursor, NAC, which seems to lead to increased glutathione throughout the body. This one study [2010] came out of the same prestigious group at Jackson Labs that brought us rapamycin.  Mean lifespan increased a stunning 25%. Two reservations: (1) they used enormous dosages, and (2) the mice on high-dose NAC ate less, so they probably benefited from caloric restriction.

Ginkgo biloba: Extract from the stinky fruit of an ancient oriental tree.  Traditionally used as a neuroprotective and concentration enhancer, for which it is mildly effective.  In 1998, a single study found 17% life extension in rats.  Who knew?


The Bottom Line

Clearly there is a great deal of promise here, but there is also much work to be done before we have it sorted out.

  • Many treatments have shown promising results in just one study, and that needs confirmation.  My top priorities would be epithalamin, NAC, and royal jelly.
  • Other treatments inspire enough confidence that we should be optimizing dosage for human use.
  • As I have written, the most important work before us now is to see how these different treatments combine.  Most combinations won’t work together, but when we find the few that synergize we will have a candidate protocol for major life extension in humans.

If you’re curious, of the substances reviewed here, I personally take metformin, aspirin, creatine and NAC.  I season with turmeric a few times a week.  I have dabbled with deprenyl and rapamycin.


* All-Cause Mortality


NF-kB Beyond Inflammation

At different times, I take about 8 different anti-inflammatory supplements, including aspirin, ibuprofen, omega 3 oils, curcumin, berberine, resveratrol, ashwaghanda, and boswellia, in addition to eating foods such as ginger, rosemary, tea and several mushroom species with anti-inflammatory effects.  There is good evidence for benefits from each of these individually, but I have no idea how they interact with one another.  Just last week, I learned that they all act (in part) through inhibition of NF-kB.

It’s certain that the separate benefits of each of these don’t just add up in combination.  It could be that all of them together are no better than just one of them individually.  It might even be that they interfere destructively with one another, competing for a common receptor, so that piling on more supplements is counter-productive.  There is no research on interactions among longevity supplements.



In this (2007) study, a multidisciplinary team performed a systematic search for blood factors that change most consistently with age over a sample of mammalian models, and organized these into modules that tend to vary in a coordinated way.  They then searched for transcription factors that can turn each module on or off.  Their most prominent finding was that NF-κB turns on the suite of factors characteristic of old age.  Out on a teleological limb, they were bold enough to call it “Enforcement of aging by continual NF-κB activity” in the title of the article.  (In this perspective, senescence is an active process, coordinated by the genome.  I agree there is good evidence for this.)

After a long path leading to NF-κB as their prime subject, the authors go on to test whether inhibiting NF-κB can have anti-aging effects.  The first obstacle that they encounter: NF-κB has important developmental functions (in young animals) and also is essential for regulating apoptosis (in older animals as well).  Mice with genes for NF-κB knocked out don’t survive gestation.  So they arranged to selectively “blockade” the binding of NF-κB to DNA in old mice, in skin cells only.  The result was a dramatic rejuvenation of the skin.



Research with rodents and humans suggest that there are factors in the blood that keep us young and, more important, factors that make us old.  Prime suspects in the latter category are the signals that dial up inflammation.  It’s my hunch that the most effective anti-aging strategy over the next 10 years will be to re-adjust signal molecules in the blood, adding what we lose with age but, more important, neutralizing or inhibiting pro-aging factors.

For various reasons, NF-κB is a good place to start.

“NF-kB has been termed the central mediator of the immune response. Gene knockout and other studies establish roles for NF-kB in the ontogeny of the immune system but also demonstrate that NF-kB participates at multiple steps during oncogenesis [ref] and the regulation of programmed cell death [ref].” [John Hiscott]

It is a complex of different molecules that acts as a master transcription factor.  It is always resident in the periphery of the cell, waiting so that it can be activated quickly when needed.  Latent, NF-κB is bound to an inhibitor molecule called IκB.  When a stimulus comes along that phosphorylates the IκB, the NF-κB is freed to enter the cell nucleus and switch on a variety of different genes, which varies from one cell type to another.  The best-known activity of NF-κB is in white blood cells (T and B cells) where it activates an inflammatory response  involving TNFa and IL-6.  Overactivity of NF-κB with age is a mediator of the systemic inflammation that contributes so much to cancer, heart disease and dementia.

NF-κB itself is not circulated in the blood, but signals in the blood can cause it to be turned on.  The Conboys early recognized NF-κB as one of the pathways that promote aging in parabiosis and transfusion experiments, where blood from older mice is introduced into younger mice.  It is a very good bet that inhibiting NF-κB would slow inflammaging, perhaps relieving arthritic and other auto-immune symptoms immediately, while reducing long-term risk of mortality and disease.


Inflammaging and Auto-immunity

Exponential amplification is a basic principle of the body’s immune response.  When the signal is received announcing an invader or an infection, there are just a few cells involved.  These send signals that trigger an immune response in other cells, triggering a chain reaction.

The beauty of such a system is that it ramps up quickly, and can mobilize a response throughout the body in short order.  This is also the danger of the system.  It requires an accurate and reliable switch to turn it off; otherwise, it can become like the Sorceror’s Apprentice, each magic broomstick producing two more to carry water until the workshop is flooded.

Note:  Dr. Katcher, in a note below, makes an important point about this positive feedback loop.

  • Senescent cells  spit out inflammatory cytokines
  • This activates NF-κB, which blocks apoptosis that could get rid of the senescent cells.
  • Inflammation from NF-κB turns more cells senescent, beginning the cycle over again.

NF-κB is a master switch that sets in motion a chain of events that is specific to a cell type and its environment.  Some auto-immune diseases (e.g., arthritis, type 1 diabetes, asthma, Crohn’s disease and irritable bowel) are associated with an excess of NF-κB [ref].  Its activation generally rises with age [in mice, in humans], but it is necessary at all ages, particularly for its contribution to the regulation of apoptosis (the selective elimination of cells that are potentially damaging).  Animals lacking NF-κB are not viable; so it will probably be necessary to strongly but selectively inhibit NF-κB, beginning in middle age.

Inflammatory responses are complex and focused on the immediate threat at hand.  NF-κB is a master switch that sets in motion a chain of events that is specific to a cell type and its environment  It’s true that without NF-κB this response doesn’t happen, but the response to NF-κB varies from cel to cell.  In this sense, inhibiting NF-κB is a kind of blunt instrument.  It works to damp the body’s inflammatory response globally, but even better would be if we could selectively shut off the body’s attack on itself.  It’s true that NF-κB activation rises with age [in mice, in humans].  But the real problem is not too much NF-κB expression, but the fact that NF-κB becomes defocused, so that the inflammatory response is not focused on a particular threat, but generalized throughout the body [ref].

Here’s an angle I learned about recently from Steve Cole:  While inflammation is an important defense against bacterial infection, it is actually counter-productive against viruses.  Inflammation can create an environment that invites viral infection, perhaps because apoptosis is suppressed.  (NF-κB suppresses apoptosis.)  Viruses aren’t so dumb, and some of them have learned the advantage of promoting NF-κB.  Some of the reason that NF-κB is upregulated with age may be a residue of chronic viral infections.  [Hiscott, again]  (Just to confuse us, NF-κB can also promote apoptosis in other contexts.)


Two pathways

All the anti-inflammatory agents that I have been able to catalog work by one or both of these two pathways:  NF-κB and COX2.  By most accounts, NF-κB is upstream of COX2, but the two are interrelated.  NF-κB regulates COX2, and also COX2 feeds back to regulate NF-κB.

NSAID drugs (aspirin, ibuprofen, naproxen, celecoxib, etc.) target cyclooxygenase-2=COX2.  Common herbal anti-inflammatories, including curcumin, resveratrol, vitamin D and omega 3 oils (the last two not exactly herbs) are active both against COX2 and NF-κB.  Inhibiting COX2 is a classic strategy for combatting arthritis.  The more potent COX2 inhibitors have a tendency to decrease cancer risk, while increasing cardiovascular risk.  This doesn’t necessarily mean, “it’s a wash”–rather the stronger NSAID’s are right for people with some genetic risk profiles and should be avoided by others.  Aspirin is the cheapest and oldest of the NSAIDs, for which there is copious data available on tens of millions of individuals.  There is reasonably good evidence that aspirin leads to lower heart risk as well, probably because of anti-clotting rather than anti-inflammatory action [read more].  Daily aspirin also lowers risk of several cancers.


Inhibiting NF-κB

Intermittent fasting or caloric restriction tends to prevent NFκB binding to chromosomes..  There’s also a long list of natural products that inhibit NFκB.

source of this chart

There are a few pharmaceutical products that inhibit NFκB, though none has been developed explicitly for this purpose.  These include emetine, fluorosalan, sunitinib malate, bithionol, narasin, tribromsalan, and lestaurtinib.  Emetine (as the name suggests) is used to induce vomiting and also to treat amoebic diseases.  It is the most potent inhibitor of NFκB among the listed drugs.  Sunitinib and Lestaurtinib are cancer drugs. Bithionol is used in de-worming animals. Narasin is an uncommon antibiotic. Tribromsalan is used externally as an antiseptic. None of these is marketed to inhibit NF-κB, and none have (to my knowledge) been tested for anti-aging properties.  The larger pool of prescription drugs that affect NF-κB are all steroids.  For example, dexamethasoneis a glucocorticoid (steroid) drug that was one of the earliest inhibitors of NF-κB to be discovered.

Many items in the list of natural products have multiple benefits. Silymarin has been reported to promote telomerase.  Rosemary and cloves protect against infection.  Berberine helps maintain insulin sensitivity, and was found to be as good as metformin in one test.  Tea polyphenols and resveratrol have been promoted as generally anti-aging.  Too much has already been written about curcumin.

New to me in this list is celastrol, an ingredient in thunder god vine (Tripterygium wilfordii).  This is a Chinese herb (leigong teng = 雷公藤), that has been prescribed for centuries in formulas to relieve arthritis, along with lupus, MS and other autoimmune disorders.  It is reported to be a powerful appetite suppressant and weight loss aid.  The trouble is that it is toxic, and the thunder god root must be prepared carefully in order to exclude triptolide, which is yet more toxic.  Experienced practitioners of traditional Chinese medicine know how to mix with other herbs and control dosage to minimize side-effects.  In the absence of this kind of expertise, I can only counsel experimenting gingerly with tiny quantities of thunder god vine in order to guage your personal response.


How important is inflammation?

It would be interesting (from a theoretical and a practical vantage) to know what is the maximum benefit available from manipulating the inflammatory pathway.  Inflammaging is linked to all the diseases of old age.  Suppose we dialed the systemic inflammation in a 80-year old back to where it was when he was 20, but we made no other change in the body.  What would be the effect on mortality and morbidity?  On vitality, resistance to infection, and stamina?  In other words, how much of the aging process is directly attributable to inflammation?

We might try to get a handle on this question via an epidemiological calculation: What is the correlation between inflammation and all-cause mortality?  If we extrapolate back to the inflammation level of a 20-year-old, how far does that go toward restoring the mortality rates of a 20-year-old?

We might think to look at genetically modified mice without NF-κB; however, they die in utero.  (There are no pure aging genes; aging is caused by re-balancing hormones and proteins, all of which have life-supporting as well as life-denying functions.)  There is a genetic variant of NF-κB that tends to be more common in centennarians than the rest of us [ref].


How much does inflammation rise with age?
Erythrocyte Sedimentation Rate and C-Reactive Protein

120 years old, the ESR test is still the most basic (and cheapest) measure of systemic inflammation.  The quantity measured is the number of red blood cells that clump together and fall out of solution in one hour.  Inflammation makes red blood cells sticky, and I’ve seen two explanations for the reason.  One is that fibrinogen, the clotting protein, rises with inflammation; the other is that the negative charge (zeta potential) naturally associated with oxygen-carrying red blood cells decreases with inflammation, so there is less mutual electrostatic repulsion.  The increase in blood’s tendency to clot that is associated with inflammation is part of the reason that inflammation is a risk for heart attacks and stroke.

C-Reactive Protein is a protein created in the liver as part of the response to inflammation.  It is easily measured with an antibody, so it has become the second most common blood test for inflammation.

ESR rises with age, but not dramatically compared to interpersonal variation:

 In fact, the difference between women and men is more than the difference between an 80-year-old and a 20-year-old of either sex.  Increase in CRP with age is even more subtle.  (This article claims it doesn’t rise at all, in a small sample of <400 patients.)

This article claims that CRP does rise with age (using a sample of 21,000):

A Glasgow study of 160,000 patients found strong correlation between CRP and near term mortality (within a year, HR=20) but not much for longer term. This is not what I was expecting.

In 26,000 patients, inflammatory markers were associated with a 1.5-fold increase in all-cause mortality (ACM) over 8 years.

A Norwegian study of 7,000 men and women found that high levels of CRP raised ACM only by a factor 1.25 (equivalent to just 2 years of aging).  For comparison, the ACM risk for an 80-year-old male is 60 times higher than a 20-year-old male.  The corresponding number for females is nearly 120.

The implication is that either inflammation is a minor (though significant) cause of mortality, or else the markers that we have for inflammation (including ESR, CRP and leucocytes) are not capturing the rise in systemic inflammation.

Hint: “Centennarians, on the other hand, manage to stave off these deleterious sequelae.Despite signs of inflammation, such as high levels of interleukin-6 (IL-6), fibrinogen, and coagulation factors, they are remarkably free of most age-related diseases that have an inflammatory component.” [ref]


NF-κB in the Brain

It is my favorite hypothesis that aging is mediated through hormonal signaling, under control of a clock in the neuroendocrine regions of the brain.  So I am interested in changing NF-κB activity in the aging brain.  This paper describes roles for NF-κB in brain development, regeneration after injury, and also evidence that NF-κB can be activated in response to nerve signals.  In the other causal direction, neural signaling (and presumably behavior) can change in response to NF-κB.  Directly on target (in my book) is this paper from Nature (2013). “By systematically controlling NF-kB activity in the hypothalamus alone, the authors are able to increase the healthspan as well as the lifespan of mice.”


The Big Picture

In the Prelude above, we found evidence that NF-κB is a master regulator that turns on a suite of genes that “enforces aging”.  But in the section, How important is inflammation?, we found evidence that, while inflammation certainly increases with age, the increase is not large compared to the scatter among individuals.  Centennarians commonly have high levels of inflammation, along with robust health.  Large increases in inflammation are common just in the last year of life, but they are not well correlated with the gradual increase in mortality with age.

The combination of these two findings suggests that NF-κB has other powerful roles in promoting senescence, in addition to its well-known role as effector of inflammation.  Maybe it is a master regulator of development and aging, akin to mTOR and FOXO.  It is a hypothesis worth testing that carefully tailored inhibition of NF-κB is a life extension strategy, so long as we can preserve apoptosis at an appropriate level.

Fasting-Mimicking Diet: Can You Make it a Habit?

I was glad to see Valter Longo’s Fasting-Mimicking diet in the news again this week.  I have been enthusiastic about Longo’s work ever since he documented altruistic suicide of yeast cells for his PhD thesis in the 1990s. Programmed death in one-celled protists was considered an affront to evolutionary theory at the time, and he had a devil of a time getting his findings into print.

Longo discovered in 2002-2005 that fasting had a powerful benefit for cancer patients, and that in conjunction with either radiation or chemo, it greatly magnified the benefits while mitigating the side effects.  Intermittent fasting had benefits, too, for the general population, independent of cancer.  It seems to be a way to get the health benefits of caloric restriction and it is easier to stick to for many people than a consistently low calorie diet.

But Longo couldn’t get either doctors or patients interested in the fasting program.  Part of the problem was the toxic mix of capitalism with medicine: the US relies on testing and promotion by profit-making companies to push medical technology forward, and fasting isn’t a product that anyone can make money on.  There was also an emotional truth: cancer patients feel scared, beleaguered, emotionally drained.  So much is dragging them way outside their comfort zone that it takes extraordinary strength not to fall back on food as one of life’s most reliable comforts.

So many medical researchers see their job as finding treatments, and leave the problem of adoption and compliance to someone else.  But Longo set himself single-mindedly to the task of bringing the benefits of fasting to a wider swath of the population.  The question that led to the Fasting-Mimicking Diet (FMD):  What dietary regimen can provide the greater part of the benefits of a water fast while inducing less hunger and minimal disruption to concentration, vitality and the pace of life?

I have done about 9 cycles of the FMD over the past 1½  years, including this week.  In my personal experience, 5 days of the FMD is eminently tolerable once I begin, though I still face resistance when I think in advance about disrupting my comforting food routines.  (Yoga, swimming and meditation have the same barriers for me–difficult in the anticipation, enjoyable once I begin.)  For me, FMD is not a weight loss program.  I gain back all the weight I’ve lost within a week after the 5-day program is finished.  Others may have different experiences.  People have used the 3-meal version of FMD (3 meals at 360 calories) as a medium-term weight-loss program, but the protein content is probably too low for those concerned about maintaining lean mass long term.

In his new study, 100 participants were randomized into two groups.  The first group did three rounds of 5 days on FMD over three months.  The second group did nothing special for three months, but were given an opportunity to try the same three rounds during the following three months.  The average weight loss was 6 pounds for those who completed all three cycles; lean body mass was lost, in the same proportion as fat.  Blood pressure, blood sugar, triglycerides all improved on average, and C-reactive protein (an inflammatory marker) went down as well.  

The study included a range of healthy people as well as people who carried more weight and had higher risk factors.  It was those with the higher inflammation and blood sugar who realized big benefits from the program, and the already-healthy were averaged in.  There is a lot of evidence to indicate that intermittent fasting works, and that the FMD delivers similar benefits.  But if you’re already lean and healthy with low blood sugar, then it’s less clear whether there are substantial additional benefits from intermittent fasting.

Notable was a reduction in the hormone IGF-1, which I don’t necessarily regard as a good thing.  On the one hand, lower IGF-1 is characteristic of all caloric restriction models, in animals and humans, in which life span is increased.  So it is an indication that the FMD was effective.  But low IGF-1 has consistently been found to increase risk for all-cause mortality, and heart disease in particular [ref, ref, ref].  Benefits of higher IGF-1 include maintenance of muscle mass and growth of nerves that diminishes with age.  

An additional benefit documented in the past is a “reset” of the immune system.  The white cell population is pruned during fasting, and the most-needed naive T-cells regrow after eating resumes.

Antidote to Obesity

It’s the (large and increasing) population of unhealthy people that Longo is targeting.  There is every reason to expect substantial benefits, but the big issue remainss: how many people can be motivated to take up the practice and stick to it?  The question was touched on only peripherally in the current study, without discussion; of 48 subjects selected for the first round, 39 stuck it out for three FMD cycles over three months (81% compliance).  That’s encouraging, but what we really want to know is: how many people will actually modify their eating rhythms for years at a time?  Will they feel the benefits and will that motivate them to stick with it month after month, five days each month?

And will this translate into long-term weight loss?  Sustaining weight loss is notoriously difficult for about 95% of the population.  People can stick to a diet for a time, but the Siren song of food is with us everywhere, and sooner or later we succumb.  Fortunately, there’s good reason to hope that the FMD discipline offers benefits even if weight loss is not sustained.


How to do it

Longo’s own company, L-Nutra offers a packaged diet, called ProLon, availble through health care professionals.  It’s pricey and may be covered by insurance.  LifeBox offers a non-prescription alternative that is not as much cheaper as it might be.  For my own experimentation, I have preferred to use fresh, whole foods approximating the same macronutrient proportions as the ProLon package.  It requires some time and attention in food prep, but it costs less than you’re currently spending on the same meals, and you can fill yourself with satisfying portions of fresh vegetables for the same 360 calories.  Here is my page of instructions and advice, with recipes designed by Enid Kassner.

For many of us, our relationship to food is central to our psychology.  Shaking up food habits disrupts everything else as well.  It’s the main reason that food habits are so hard to change, but for me, it’s also a good thing.  I enjoy the challenge and the self-awareness that come from a new frame of reference; fasting changes my perspective, my emotional baseline, and my mental state.  For me, the first day is unfocused, low energy, but often a time of creative new ideas; the second day is distracted, obsessive, sometimes headache-y or otherwise uncomfortable, and beginning with the third day there is returning energy, along with a freedom that I didn’t know I missed.


Why is life expectancy in America lagging?

Part of the answer is certainly cultural.  Advertising, parties, lunch and dinner meetings often reinforce consumption of food that is designed to be addictive for the sake of corporate profits.  In America, we are surrounded by overweight people, but France and Italy have much lower obesity rates, and you can walk all day around the cities of Japan or China without encountering anyone who is seriously overweight.  Even in America, the problem has grown way out of proportion only in the last 40 years.  This and income disparity are the main reasons that life expectancy in America is at the bottom of the developed world.  Our unaffordable, dysfunctional healthcare system provides many additional reasons.  Meanwhile, life expectancy in Asia is climbing at an exemplary pace.

Longo’s FMD is designed to address this most accessible factor in the diseases of late life for a large swath of people who find they cannot lose weight.  His research is based not just on effectiveness but equally important on tolerability.  How many people will adopt it and reap the benefits?  This will be an important question for public health going forward.  But you are a unique individual, not a statistical median.  I encourage you to experiment with FMD, see what you learn about yourself, and decide if it can be a valuable part of your health program in the long term.

Glycine and Mitochondria

A venerable theory of aging is the Mitochondrial Free Radical Theory (MFRTA).  Mitochondria are the energy factories of the cell, where sugar is burned to create electrochemical energy.  Of necessity, the mitochondria use high-energy chemistry, and this creates toxic waste in the form of ROS–pieces of molecules that are too eager to combine with delicate biomolecules, turning useful compounds to toxic waste.

The MFR theory says that these ROS cause mutations in the DNA of the mitochondria that build up over time and cause the mitochondria to perform less well with age.  Mitochondria are constantly turning over, that is, creating new mitochondria that inherit the mutations and accumulate new ones.

Over the years, this story has come apart.  The key finding goes back to 1980 : mutations (for whatever reason) are not more severe in older people than in younger people.  The mutations that appear in mitochondria with age are at a low level, and inconsistent with the assumed ROS mechanism [2013].

But it remains undeniable that we have fewer mitochondria as we get older, and those we have become less efficient.  Brain and muscle cells are the most energy intensive, and we have less energy for everything from running to thinking.  Mitochondria are not the source of age-related decline; nevertheless maintaining (or restoring) mitochondrial health should be a part of any strategy to resist the ravages of age.

I recently became aware of this Nature paper from Japan:  More important than genetic changes in old mitochondria are the epigenetic changes (changes in gene expression) that render them less efficient.  Is there a way to restore the gene regulation in aging mitochondria to look more like the gene expression in energetic, young mitochondria?

“When glycine was added to culture media containing cells from the 97-year-old, the mitochondria in these cells became like new.” [quote from summary by PD Mangan].  Glycine is the simplest of the 20 amino acids that are building blocks of proteins in all eukaryotes.  It is not classed as an “essential amino acid” because our bodies can manufacture glycine, but maybe we don’t make enough of it to maximize our lifespans.  



The theory in the Japanese paper is that glycine treats the downstream symptom of epigenetic reprogramming in the mitochondria.  In other words, glycine does not stop the detrimental epigenetic changes in mitochondria that come with age, however one of the most important of these changes results in a glycine shortage in the mitochondria.  Hence, glycine supplementation effectively attacks the problem at an intermediate stage.

Could a molecule as simple (non-specific) as glycine be an anti-aging compound?  Glycine comes to us with a sketchy but promising history.  In one rat study, a hefty dose of glycine increased lifespan by 27% longer than controls.  “Hefty” is the human equivalent of ~3 ounces per day.  I’m tentatively filing this study in the “too good to be true” drawer, because it appeared only as a conference abstract 5 years ago and has never been fleshed out with a peer-reviewed full text.

A shortage of protein has a powerful anti-aging effect across many species.  And a shortage of one critical amino acid–methionine–is sufficient to trigger this response.  This may be because methionine is the “start codon”; every gene begins with a methionine, and a severe shortage of methionine can slow down all protein synthesis.  

Directly engineering a shortage of methionine in the human body is just too difficult to manage, because too many protein foods have methionine, and we’re too fond of protein.  (Animal proteins are consistently loaded with methionine, whereas some vegetable sources have less.)  In studies of lab animals, a methionine shortage is engineered by using fully artificial protein sources, constituted from individual amino acids.  People would never want to live this way on synthetic food, even if we could afford it; but using glycine to create a methionine shortage sounds more palatable.  Glycine plays a role in breaking down methionine in the liver, and if the glycine level is jacked up super-high, it is (theoretically) possible to force this reaction so far as to create a methionine shortage.

For some of us, methionine restriction holds up the tantalizing prospect of gaining benefits of dietary restriction while allowing us to eat to satiety.  But the idea remains untested in humans.  Protein deficiency can lead to loss of strength and endurance and the ability to concentrate–even as it increases life expectancy.  Depression is another risk.  Rats that have tried methionine restriction are not recommending it for humans; in fact, they quickly come to crave methionine; they recognize methionine-deficient foods and shun them.

On the other hand, there are other diverse benefits documented for glycine supplementation, beginning with better sleep, insulin sensitivity and cancer resistance.  A minimum of 3 or 4 grams is required to have any effect.  You can buy it in powder form by the pound.  From Finland, here’s Valdu Heiskanen’s comprehensive page on glycine.


Mitochondria have their own DNA

Hundreds (sometimes thousands) of mitochondria dot every cell in our bodies.  They perform the task of burning sugar in a controlled process that captures most of the energy in electrochemical form (ATP) that is convenient for all the cell’s usage.  In the deep evolutionary past, mitochondria were an invading bacteria, which gradually lost their virulence, then became domesticated in a symbiotic relationship, then fell into line doing the bidding of the cell nucleus (like other parts of the cell).  But from that distant era they still retain a snippet of their own DNA–just 37 genes, all essential for the energy metabolism.   

In the old MFR theory, mitochondria were thought to lose genetic integrity through mutations.  In the new view, the genetic information isn’t lost, but the mitochondrial DNA is reprogrammed later in life, with the result that their performance suffers.  Nominally, this is a promising finding; random mutations in a hundred trillion mitochondria would not be a feasible target for anti-aging interventions; but epigenetic reprogramming is presumably something the cell already knows how to do.  The cell knows, but we don’t; our understanding of epigenetic markers and the way that they are programmed is still rudimentary (even in the nucleus, let alone the mitochondria).  Our best hope for the near term would be if we don’t have to understand the process, because the nucleus takes care of the details.  This brings us back to the general strategy of signaling to make each cell think it’s part of a young body.

How does PQQ work?

PGC-1a is a circulating hormone that says to the cell, “make more mitochondria.”  You can’t take PGC-1a orally because it is a large protein molecule, and does not survive digestion.  PQQ is a small molecule, more bioavailable when ingested, that increases circulating PGC-1a.  The two-step process has been documented in rodents; oral PQQ leads to more mitochondria [ref, ref].  


Does CoQ10 help?

CoQ10 (or ubiquinone) is essential to the metabolic function of mitochondria.  Supplementation with CoQ10 has been found to enhance athletic stamina in most human studies [ref, ref, ref, exception].  This benefit is not to be sneered at, though it is unrelated to aging.  Heart patients taking statin drugs have an induced deficiency in CoQ10, and need to take supplements.  Other studies of CoQ10 suggest benefits for cardiovascular risk [ref] and for maintaining insulin sensitivity [ref].  On the negative side, CoQ10 cannot stimulate growth of new mitochondria, and rodent studies with CoQ10 have never demonstrated increased life span [ref, ref].



Exercise is the best thing we know for promoting replication of mitochondria.  This has been substantiated in humans and in rodents.  Exercise is a powerful stimulant for producing PGC-1a, and there are additional channels by which exercise promotes mitochondrial biogenesis, apart from PGC-1a [ref].  There is evidence for endurance exercise and interval training, but maybe not for strength training [another ref].  I was unable to find any direct comparison of the three.


Fasting and Ketogenic Diets

Fasting promotes mitochondrial biogenesis by a different pathway: AMPK [ref].  AMPK is expressed in response to a tight energy budget, but the AMPK response also decreases with age [ref].  Ketogenic diets (very low carb) also promote increases in mitochondria [in humans, in mice].

Chronic caloric restriction (as opposed to intermittent fasting) contributes to the health of mitochondria, but not to their number [ref].


The Bottom Line

Loss of Mitochondrial energy is connected to many of the deficits of old age; but most of the things you can do to improve mitochondrial function are the same things we do for a generalized anti-aging program.  The new thing here is glycine.  It’s $10 a pound and helps you sleep better.

I’m grateful to P. D. Mangan at Rogue Health for providing the inspiration and seed references that got me started on this story [link].

First Fruits of Research with Young Blood Plasma

A recurrent theme on this page is the idea that human aging is driven by a combination of proteins circulating in the blood.  Blood is not just red cells and white cells; there is the blood plasma which contains thousands of dissolved proteins (and RNAs), signal molecules which regulate all aspects of metabolism, on time scales ranging from minutes to decades.  As we get older, the mix of these protein signals changes in ways that are relatively subtle, with less of some proteins and more of others.  It has been pretty well established that the mix of proteins is characteristic of your age.  My bet is that the mix of proteins actually determines your age, in the sense that changing the  blood plasma of an old person to that of a young person will, to a significant degree, transform the metabolism toward a younger state.

The promise of this work came to prominence in parabiosis experiments with mice, beginning about 2005 out of Stanford.  Old mice were surgically paired with young mice, so their circulation was tied together.  The old mice become younger and the young mice became older.  In the intervening years, we have learned that blood plasma (no cells) from young animals has a rejuvenating effect on old animals.

But giving old people frequent transfusions from young donors sounds like an experimental procedure for aging tycoons, not a practical plan for population-wide life extension.  Alternatively, to reproduce the full suite proteins in young blood artificially is a daunting task.  Are all the proteins necessary for rejuvenation, or, perhaps, might the same success can be achieved with just a small number of proteins?   Some would be added, others effectively subtracted from the blood by blocking their receptors with an inhibitor.

So the race is on to find candidates for proteins in the blood that could be part of this small subset, a handful of proteins that might, if we’re lucky, stand in for the thousands whose concentrations change with age.  The Stanford students from 2005 have graduated and now have labs of their own at Berkeley and Harvard  In the last few years, Mike and Irina Conboy of Berkeley identified oxytocin as a key protein, and Amy Wagers at Harvard identified GDF11, both proteins that we lose with age, and concentrations might be beefed up for rejuvenation.  Oxytocin is holding up; there is controversy about GDF11.

But more effective than adding “youth factors” to old blood may be removal of pro-aging factors.  This was the preliminary finding put out by the Conboys a few months ago.  Right around this time, from the lab of Tony Wyss-Coray at Stanford, came the first report of anti-aging benefits from blocking a circulating protein.  VCAM-1 is a protein that increases with age, but has not previously been identified as a bad actor of primary import.  The “CA” in the middle of VCAM stands for cell adhesion, an essential cell function which in itself is not good or bad.  Cells stick together for many reasons.  But VCAM-1 has been loosely linked in the past to cardiovascular disease and to arthritis.

Hanadie Yousef, a post-doc at Wyss-Coray’s Stanford lab, presented preliminary results at a Neuroscience meeting in November, indicating that

  • VCAM-1 increases by only about 30% in blood of the elderly, but this is enough to make a difference.
  • Higher levels of inflammation and lower nerve growth in brains of older mice were linked to VCAM-1
  • An antibody that binds to VCAM-1 and pulls it out of circulation was successfully used to prevent these effects.  Inflammation and nerve growth were both restored to levels typical of young mice.

Of course the findings are preliminary, and yet unpublished [Yousef abstract].  No anti-aging has been demonstrated in normal, living mice, but the benefit of intravenous antibody injections has been demonstrated in mice that are served up artificially with too much VCAM-1, and the molecular mechanism has been validated in cell cultures.

I find it promising that the research is being done on brain function.  The central timekeeper that coordinates change in blood chemistry through a lifetime has not yet been identified, but neuroendocrine regions of the brain are a promising place to look for it.  Human clocks are built on feedback loops, and if evolution’s engineering immitates human arts, then we might look for an epigenetic aging clock based on secretions from the brain that feed back to act indirectly on the brain.

Other blood proteins that increase with age, and which presumably could be targets for antibody therapies include the pro-inflammatory signals NFkB and TGF-ß, also the reproductive hormones LH and FSH.

I believe that the work of these three groups is the best prospect we have for powerful human anti-aging interventions in the medium term.  In the short term, I think that senolytic agents will be the Next Big Thing.  In the long term, we will learn how to reprogram our epigenetics.  For the next decade or two, keep an eye on ciculating blood signals

Three previous posts with background on this subject:

How does the body’s hormonal signaling change with age?
Signal molecules in the blood: what do we have too much as we age?
Signal molecules in the blood: what do we lose with age?

Epigenetics and the Direction of Anti-Aging Science

Dear Readers –

It’s been a deeply gratifying year for me.  Twenty years ago, I first started writing that aging is something the body does to itself, a body function, rather than deterioration or loss of function.  Journals would not even send my submission out for peer review.  Journal of Theoretical Biology sent me the considered opinion of their anonymous reviewer, “JTB shouldn’t touch this topic with a ten-foot pole.”  The conflict with prevailling evolutionary theory was just too deep.

But in the interim, the evidence has continued to pile up, and many medical researchers have taken the message to heart in a practical way, setting aside the evolutionary question and just pursuing approaches that seem to work.  The most promising developments in anti-aging medicine involve changing the signaling environment rather than trying to “fix what goes wrong” with the body.

My popular book exploring the evolutionary origins of aging (and implications for medical science) came out in June, and an academic version of the same content came out in October.  Gandhi taught me,

“First they ignore you…
then they laugh at you…
then they fight you…
then you win.”

The paradigm of programmed aging passed this year from stage 2 to stage 3, with prominent articles arguing against the possibility of programmed aging [Kirkwood, de Grey, Vijg & Kennedy].  Current Aging Sciences devoted a full issue to the question.  I welcome the discussion.  This is a debate that colleagues and I have sought to initiate for many years.  There are powerful theoretical arguments on one side, and diverse empirical observations on the other.  The scientific community will eventually opt for empiricism, but not until theory digs in its heels and fights to the death.  A basic principle of evolution is at stake, and many theorists will rise to defend the basis of their life work; but a re-evaluation of basic evolutionary theory is long overdue.

The idea that fitness consists in reproducing as fast as possible is no longer tenable.  For plants, this may be approximately true.  But animal populations cannot afford to reproduce at a pace faster than the base of their food chain can support.  Animals that exploit their food supply unsustainably will starve their own children, and there is no evolutionary future in that.  This is a principle that links together entire ecologies, and the foundation of evolutionary theory will have to be rewritten to take it into account.


The Programmed Aging Paradigm: Is it a Cause for Optimism in the Quest for Extended Human Life?

For many years, I put forward the argument that programmed aging means there are genes that serve no other purpose than to hasten our death, and that medical research should be targeting the products of those genes.  (Once a pathway has been identified, pharmaceutical science knows well how to block it with engineered drugs, like beta blockers and MAO inhibitors and serotonin re-uptake inhibitors.)

But in recent years, epigenetics has eclipsed genetics as the major theme in molecular biology.  Everything that happens in the body is determined by which genes are expressed where and when.  The vast majority of our DNA is devoted not to coding of proteins but to promoter and repressor regions that control gene expression with exquisite subtlety.

There has been a growing recognition of aging as an epigenetic program.  As we get older, genes that protect us are dialed down, and genes for inflammation and apoptosis are dialed up so high that healthy tissue is being destroyed.  Many epigenetic scientists have discovered this, and they find it natural to see aging as a programmed phenomenon.  (Most have never been to graduate courses in evolutionary science, where they would have been indoctrinated into the perspective of the selfish gene.)

At first blush, it seems that an epigenetic program is just as amenable to pharmaceutical intervention as a genetic program.  A few years ago, I wrote about transcription factors as the key to aging.  Transcription factors bind to DNA and turn whole suites of genes on and off in a coordinated way.  If we can restore a youthful transcription environment in an older animal or human, the body knows how to repair damage and re-create a younger self.  The model I had in mind was based on a small number of powerful transcription factors controlling expression of a much larger number of genes, controlling a yet larger population of metabolites.

I no longer believe in this model.

This summer, I had a chance to work in a worm genetics lab and consult closely with people who know the experimental details.  I learned that there is no clear line between functional proteins and transcription factors, that many proteins have multiple functions, and that metabolites feed back to control gene expression.  Instead of a pyramid, I should think of a web of causes and effects.

The entire system is primed for homeostasis, meaning that it responds to any intervention, seeking to move the system back toward its previous state.  Of course, it is this capacity for recovery that makes life robust; but it also means that there is no “command central” which can be tweaked to move the whole system at once toward a desired state.

I still believe that there are one or more aging clocks that inform the body of an age-appropriate metabolic state, and synchronize the aging of different systems.  Telomere length is one such clock.  If we can reset an aging clock, the body will repair and clean itself up.  If we can reset several clocks, the body may be able to restore itself to a younger state.  But I recognize the possibility that the clock is diffused through the detailed epigenetic status of a trillion cells, and may be beyond the reach of foreseeable technology.

A few years ago, Steve Horvath of UCLA gave us the most explicit picture of an aging clock.  He found it in one particular epigenetic marker: the pattern of DNA methylation.  The Horvath clock is distributed over 353 sites.  This is a clock that can be read for any given cell, but can it be changed or adjusted in each of the body’s trillions of cells?  The prospect is daunting, and we do not yet know how to go about it.  2016 saw the first use of CRISPR technology for therapy in a living human.  CRISPR could, in principle, be used to alter gene expression, one gene at a time.  To re-regulate the expression of 353 genes in one treatment would probably require new concepts and new discoveries.

Short of resetting the aging clock, there are several technologies just over the horizon that should offer substantial life extension benefit.  I believe the best prospects are senolytics (ridding the body of senescent cells), telomerase activators (rejuvenating old stem cells), and adjusting blood levels of key hormones and cytokines that increase or decrease with age.


The Bottom Line

Programmed aging is the right model to keep in mind as we search for interventions that slow the aging process and lessen the incidence of heart disease, cancer and Alzheimer’s all at once.  Prospects are good for real breakthroughs, perhaps as soon as 2017, but I am no longer as optimistic as I was just a few years ago that complete rejuvenation is on the horizon.

Wishing you health and vitality for the coming year,




– Josh Mitteldorf

From Santa Diego, a Jolla Xmas Gift

From the Salk Institute in La Jolla, CA came an announcement last week that the four factors previously identified to turn ordinary cells into stem cells (in cell cultures) was successfully used as a rejuvenation procedure in live mice.  The results provide important new evidence for the hypothesis that aging is under epigenetic control, and a proof of principle that we might slow aging by modifying the chromosome markers and attachments that determine gene expression.  But the way in which this was done involved genetic engineering before birth, and there is no obvious way to translate the results quickly into an anti-aging teatment for living humans.

Ten years ago, Shinya Yamanaka’s Kyoto University laboratory announced that just four proteins could turn an ordinary, differentiated cell back into the stem cell from whence it came.  The four were transcription factors, high level switches that turn whole systems of genes on and off with one signal, and the “Yamanaka factors” became known by their initials, OSKM.

Last week, Izpisua Delmonte’s laboratory at the Salk Institute announced a success in rejuvenating whole animals, live mice, using the same OSKM.

Whether this is the germ of a potent new rejuvenation treatment remains to be seen; but the immediate message is a dramatic affirmation of the new paradigm in anti-aging medicine: aging can be reversed by signaling, without artificially-engineered repair of damage.  A bold form of this paradigm is the epigenetic hypothesis—now just 4 years old—which says that aging is controlled by gene expression.  It is the set of genes that are turned on and off, and the genes’ levels of expression that determine the state of the body’s age.  (This idea does not deny that tissues and biomolecules suffer damage with age; but the hypothesis says that the body knew how to repair this damage at one time, and is capable of repairing the damage again, when the signal molecules engage repair mechanisms appropriately for a young individual.)

Gene expression  is controlled, in turn, by markers on the chromosome and on the histone spool around which the DNA is wrapped like thread on a spool.  These markers are known to change with age in a characteristic pattern.  Shifting epigenetic markers program all the stages of development, and (according to the hypothesis), the program continues, and causes the body to pass through the stages of aging.

But in nature this clock never goes backward.  The epigenetic clock is reset to zero as the genome is wiped clean and reprogrammed.  This happens twice: once in the creation of germ cells, the sperm and egg; and a second time after sperm and egg join to make a zygote.  (This is a simplification; some traits are epigenetically inherited, implying that some genome markers are retained and pass across generations.)

If we buy the epigenetic hypothesis, then the holy grail of anti-aging medicine would be to reset all the epigenetic markers, say from age 60 to age 20, but not all the way back to zero.  This must be “possible” in some sense of the word; but if it depends on us to read (for example) the methylation of a 20-year-old’s chromosomes and write the results onto the chromosomes of a 60-year-old, in every cell of the body, without otherwise disrupting the living organism, then the task is daunting.  And methylation is just one of about 100 known epigenetic modifications of the chromatin.

Nature knows how to reset the epigenetic clock all the way to age 0, but there is no precedent for a partial reset.  All tissue differentiation is lost, and the growth rate is pedal-to-the-metal high.  It should be no surprise that previous attempts to rejuvenate the living mouse by resetting the clock with OSKM have led to cancer disasters [ref, ref].  In this new report, the Salk researchers used short, intermittent exposure to OSKM to “partially reset” the epigenome.  If this really works, and if the epigenetic hypothesis continues to pan out, then this is indeed a week to celebrate.


The experiment

The procedure was first tested in human cell cultures, demonstrating “partial de-differentiation”, where functional cells were rejuvenated without returning them completely to stem cell status.  This was an important proof of concept.  The authors cite previous experiments suggesting that OSKM re-setting is a multi-step process, so it is possible in principle to halt the process after partial re-programming, and hope for a somewhat younger state.

Next, the procedure was tested on mice with genetically short life spans, living an average of  just 18 weeks.  Mice with the OSKM treatment lived 24 weeks.  Impressively, the treatment was tuned so that it did not increase cancer rates.  The particular life-shortening gene was defective LMNA (Lamin A).  Lamin A is important for structure and function in the cell nucleus (details hazy), and there is no way to distinguish from this experiment whether the OSKM treatment merely counteracts the deficiency of Lamin A or whether it slows aging generally. Finally, the procedure was tested in normal, aged mice.  They showed signs of improved healing, nerve regrowth, and mitochondrial chemistry typical of younger mice.  But the mice were sacrificed to determine these things, so there was no demonstration of increased lifespan for genetically normal mice.  Sometimes “publish or perish” pressure leads researchers to kill the goose that lays the golden egg…

But the big asterisk on this new result is that the delivery system was through a gene added to the mice at the egg stage.  It is easy to modify genes at the egg stage, when there is just one cell, and then the modification is copied in every cell of the adult; but to do gene therapy for adult humans is still at an early experimental stage.  Every cell in their bodies had an extra copy of each of the 4 genes for the OSKM factors, and these genes were so configured that they could be turned on and off with a drug (doxycycline).  Administration of the drug was arranged to be just right to reprogram the cells, but not all the way.  Optimum was found to be a low dose, just two days a week.


Theoretical hedging

Bench scientists have learned to adopt the epigenetic hypothesis in practice, but some are still bound to the obsolete theoretical ideas, inherited from sclerotic thinking about “selfish genes”.  Belmonte was quoted as saying the epigenome becomes “damaged” late in life “At the end of life there are many marks and it is difficult for the cell to read them.”

But studies of aging epigenomics show that in addition to random changes in the epigenetic state, there are definite, programmed changes—enough to make an accurate epigenetic clock—and that some of these changes turn down cell repair functions and turn up inflammation.  Aging involves a loss of order (“damage”), but it also entails a set of programmed changes.  It is the latter that we may hope to address through a streamlined, signaling approach to anti-aging medicine, and, if we are lucky, the body may take up the ball from here and undo part or all of the damage.


The bottom line

This is an important new confirmation of the epigenetic hypothesis.  Previous confirmations were

  • in parabiosis experiments, but the experiment could not be continued long enough to be sure that lifespan was extended
  • in “methylation clock” measurements, but there has been no way to distinguish whether epigenetic changes were a cause or a result of aging.

This new experiment shows that epigenetic changes can extend lifespan.  But the experiment offers no clear extrapolation to life extension for humans.  The treatment depends on four large molecules that need to be delivered to every cell nucleus in the body.  These molecules cannot be taken orally because they will not survive digestion, and even intravenous delivery will not get the molecules to cell nuclei where they are needed.

In cell cultures with the OSKM factors applied externally, stem cell yields are still just a few percent, even after ten years of experience.

The Salk researchers got around this by inserting the OSKM genes into the cell, but for already-living humans this is not a possibility.  The best we know how to do is to modify some of the body’s cells with gene therapy; CRISPR in living humans is itself a new technique in its experimental phase.

So for the foreseeable future, I see a two-pronged approach to cell-level rejuvenation.  One is to remove senescent cells (senolytics); and the other is stem cell removal, rejuvenation, multiplication in vitro, and return to the body.  OSKM may be useful in this second step, rejuvenation of stem cells in vivo.