Supplementation with Glutathione Precursors Improves Mitochondrial Function, Reduces Oxidative Stress and Inflammation

Mitochondria are the power plants of the cell, turning out the chemical energy store molecule ATP that is needed to power cellular processes. Mitochondrial function declines with age, and this faltering of energy production is an important contribution to degenerative aging. A broad range of proximate causes have been identified, changes in gene expression that directly or indirectly disrupt the supply of rate-limiting molecules necessary for mitochondria to carry out their work. Researchers identified loss of NAD+ as one of those issues some years ago, and supplementation with precursor compounds derived from vitamin B3 (such as nicotinamide riboside) has been shown to increase NAD+ levels and improve mitochondrial function. Today's research materials report on an analogous effort to raise levels of the antioxidant glutathione, also lost with age, by supplementing with a combination of precursor compounds glycine and N-acetylcysteine.

Antioxidants are important to mitochondrial function and cell health. Creating ATP is an energetic process, producing reactive oxidizing molecules as a necessary side-effect. Too much oxidation harms the cell, though some oxidation is needed as a signaling mechanism. Cells employ antioxidants to soak up the excess. Researchers have in the past shown benefits in mice through genetic engineering to upregulate the natural mitochondrial antioxidant catalase, while mitochondrially targeted antioxidant compounds such as MitoQ and SKQ1 have also resulted in animal studies showing improvements in health and a modest extension of life span.

The results reported in this small pilot human study of glycine and N-acetylcysteine supplementation appear interesting, particularly given that the intervention doesn't just improve mitochondrial function, but also improves markers of age-related chronic inflammation. Exercise is more effective at increasing NAD+ levels than the present methods of NAD+ precursor supplementation, at least in published clinical trial data. Exercise is known to increase glutathione levels as well, but is it better for glutathione levels than this approach to precursor supplementation? Looking at blood samples or red blood cells, a 2007 study shows a ~25% increase in glutathione via exercise, which is considerably smaller than the ~100% increase via supplementation claimed in the present study. That suggests it to be worth the expense to replicate this outcome in a larger study.

For those who are minded to responsibly repeat this study as a self-experiment at home, hopefully also discussing with a physician beforehand and taking blood tests before and after to see how the metrics hold up, I should note that glycine and N-acetylcysteine are both easily obtained. They are existing supplements, widely used. Shop around, prices vary considerably. Per the papers, the daily intake of each supplement is large: ~100 mg/kg for glycine (~6 grams for a 60kg human) and ~130 mg/kg for N-acetylcysteine (~8 grams for a 60kg human), split into two doses.

GlyNAC improves strength and cognition in older humans

A pilot human clinical trial in eight older adults 70 to 80 years of age reveals that supplementation with GlyNAC - a combination of glycine and N-acetylcysteine as precursors of the natural antioxidant glutathione - could improve many age-associated defects in older humans to improve muscle strength and cognition, and promote healthy aging. The study participants taking GlyNAC for 24 weeks saw improvements in many characteristic defects of aging, including glutathione deficiency, oxidative stress, mitochondrial dysfunction, inflammation, insulin resistance, endothelial dysfunction, body fat, genomic toxicity, muscle strength, gait speed, exercise capacity, and cognitive function. The benefits declined after stopping supplementation for 12 weeks. GlyNAC supplementation was well tolerated during the study period.

As mitochondria generate energy, they produce waste products such as free radicals. These highly reactive molecules can damage cells, membranes, lipids, proteins, and DNA. Cells depend on antioxidants, such as glutathione, the most abundant antioxidant in our cells, to neutralize these toxic free radicals. Failing to neutralize free radicals leads to harmful and damaging oxidative stress that can affect mitochondrial function. Interestingly, glutathione levels in older people are much lower than those in younger people, and the levels of oxidative stress are much higher. Animal studies have shown that restoring glutathione levels by providing GlyNAC reverses glutathione deficiency, reduces oxidative stress, and fully restores mitochondrial function in aged mice.

Glycine and N-acetylcysteine (GlyNAC) supplementation in older adults improves glutathione deficiency, oxidative stress, mitochondrial dysfunction, inflammation, insulin resistance, endothelial dysfunction, genotoxicity, muscle strength, and cognition: Results of a pilot clinical trial

Oxidative stress (OxS) and mitochondrial dysfunction are implicated as causative factors for aging. Older adults (OAs) have an increased prevalence of elevated OxS, impaired mitochondrial fuel-oxidation (MFO), elevated inflammation, endothelial dysfunction, insulin resistance, cognitive decline, muscle weakness, and sarcopenia, but contributing mechanisms are unknown, and interventions are limited/lacking. We previously reported that inducing deficiency of the antioxidant tripeptide glutathione (GSH) in young mice results in mitochondrial dysfunction, and that supplementing GlyNAC (combination of glycine and N-acetylcysteine [NAC]) in aged mice improves naturally-occurring GSH deficiency, mitochondrial impairment, OxS, and insulin resistance.

This pilot trial in OA was conducted to test the effect of GlyNAC supplementation and withdrawal on intracellular GSH concentrations, OxS, MFO, inflammation, endothelial function, genotoxicity, muscle and glucose metabolism, body composition, strength, and cognition. A 36-week open-label clinical trial was conducted in eight OAs and eight young adults (YAs). OAs were studied again after GlyNAC supplementation for 24 weeks, and GlyNAC withdrawal for 12 weeks.

GlyNAC supplementation for 24 weeks in OA corrected red blood cell GSH deficiency, OxS, and mitochondrial dysfunction; and improved inflammation, endothelial dysfunction, insulin-resistance, genomic-damage, cognition, strength, gait-speed, and exercise capacity; and lowered body-fat and waist-circumference. However, benefits declined after stopping GlyNAC supplementation for 12 weeks.


I'm surprised that no one noticed these results before, given that these are both commonly used supplements. Maybe because of the high dosage required? For self-experimentation, I might be concerned with hypertension caused by NAC, as per:

This is pretty cool as an easily accessible low-hanging fruit though.

Posted by: gheme at March 31st, 2021 7:23 PM

Is this study a cause for concern about mitoq as a supplement?

The targeted anti-oxidant MitoQ causes mitochondrial swelling and depolarization in kidney tissue

Posted by: august33 at March 31st, 2021 10:09 PM

@august33: Thanks for the abstract on MitoQ. I didn't knew that have used it for a few months. Now I will pause before I learn more. Im not a biotechnologist so have difficulty understanding those papers. Is it more dangerous then beneficial? Should I throw them away?

Posted by: Gekki at April 1st, 2021 5:59 AM

This is so cool! Thanks. This is nice confirmation of what was (to me) kind of a no-brainer, many years ago, when I ordered my first 25-kg sacks of glycine and glutamine (along with NAC, a kilo or so): supplement with freaking glutathione precursors, baby! Precursors which have numerous benefits apart from (as far as anyone knows) glutathione upreg.
They did forget the glutamine, a very important amino in many ways. Whatever. Glycine+NAC is a great start. Glycine alone has more-than-appreciable variety of beneficial effects. CHEAP, too.
Also they did not mention megavitamins to upreg glutathione production -- an action probably limited by precursor shortfalls if one does not also supplement with them. High niacin and thiamine are very nice for this, a few grams per day.
Great stuff, thanks.

Posted by: alan2102 at April 3rd, 2021 12:18 PM

Followup: notes and ideas on doses, dosing:

Authors of the article insisted on the absurdly obscure quantitative signifier "mmol", forcing
readers to undertake a bunch of unnecessary technical lookups and arithmetic just to know what the fuck they are talking about.

full text is here:

Full text of article states: "GlyNAC was provided as capsules of glycine (1.31 mmol/kg/d) and cysteine (0.83 mmol/kg/d, provided as N-acetylcysteine, NAC)"

Glycine has MW of 75, hence one mole = 75 grams, hence 1.3 mmol (thousandths of a mole) = 100 mgs, times bodyweight in KGs, typically ~70, hence glycine dose was ~7 grams/day, adjusting up or down modestly depending on actual bodyweight.

Cysteine has MW of 121, hence one mole = 121 grams, hence .83 mmol (thousandths of a mole) = 109 mgs, times bodyweight in KGs, typically ~70, hence cysteine dose was ~7-8 grams/day, adjusting up or down modestly depending on actual bodyweight.

If my data and math is correct (is it?), that's a rather bad proportion!

Sulfur-bearing amino acids are potentially toxic and should be used with care. This can be overstated; it is not that they are necessarily toxic, only that they should be used with care. The therapeutic window is not as wide as with many other aminos/nutrients. For example, glycine, an extremely non-toxic amino, has been used therapeutically in SCORES of grams per day dose, over extended periods. The late Frederick Klenner, in the 1950s and 60s, recommended tablespoon doses (12-15 grams) several times daily, long term, in a variety of diseases. (He thought it a good general complement to the other mega-nutrients he was using -- citing its central precursor role v/v glutathione, creatine, heme, connective tissue, and so on -- and he was right.)

In contrast, most NAC trials use 2-3 grams/day; 600 mg QID is popular. In cardiovascular settings, high-dose NAC (15 grams/day) has been used, but only for a couple days, such as post-infarct. It would be risky or reckless to use such high doses for an extended period. A case has been reported of hemolysis and acute renal failure in a woman accidentally given a massive dose of NAC: 52 grams, IV, in one hour, followed by 17 grams over the next four hours (PMID 21970774). That's an extreme case, but still.

Note that the MW of NAC is 163; i.e. cysteine is only ~75% of it. That means that, in this paper, the 7-8 gram cysteine dose is ~11 grams of NAC. To my eyes, that is getting into a problematic range for long-term use, especially in the context of such a low dose of glycine.

A safer, more sensible dose ratio would be 15-20 grams glycine to 2-4 grams NAC, perhaps 5-6 if you feel adventurous. Preferably, give the great amino acid and glutathione precursor glutamine along with, in liberal but smaller amounts (~10 grams). Also, stimulate glutathione-synthetic pathways modestly with megadose niacin, thiamine and ascorbic acid, to increase likelihood of administered cysteine being incorporated into glutathione (rather than floating around freely and... who knows? possibly causing some problem).

If I wanted to further increase my organic sulfur exposure, I would do it with taurine, the least toxic of the sulfur-bearing aminos, and one with an amazing array of benefits, including upregulation of glutathione.

Some practical observations: I've found these aminos easy to take, multiple times daily, off the spoon. I do not bother mixing them with anything. Glycine has a slightly repulsive off-sweet taste (off enough that you could not use it as sugar substitute); glutamine has almost no taste; NAC is tart but not unpleasant. Glycine, when mixed in fluid, actually tastes much worse than when taking it off the spoon. When in solution, it apparently floods taste receptors with its very-slightly-nauseating taste; this is avoided when taking it in a bolus off the spoon, I have found. All three aminos are in permanent jars (big for the GLY+GLN, small for the NAC) on my kitchen counter. Right next to the niacin and thiamine and taurine jars. :-)

Just my .02 on this glorious sunny April day.

PS: you might be interested in:
Int J Epidemiol. 2018 Feb 1;47(1):311-320. doi: 10.1093/ije/dyx234.
Dietary glutamine, glutamate and mortality: two large prospective studies in US men and women

Posted by: alan2102 at April 3rd, 2021 2:03 PM

alan2102 - Where do you purchase your supplements?
Any other suggestions welcome!
I used to purchase powders from VRP many years ago, but they became more mainstream and discontinued many products.....
I always thought my program of 2 grams NACysteine daily was significant - also usually recommended to take with C and B6 - these doses here are on another level....

Posted by: Jack Crain at April 5th, 2021 12:15 AM

@alan2102 : I think you are slightly off in the cysteine calculation:

0.83 mmol/kg/d = 0.83 / 1000 mol * 121.16 g/mol = 0.83 / 1000 * 121.16 = 0.1005628 gram

Posted by: Ray at April 5th, 2021 11:05 AM

Ray: You're right! Thanks. I rechecked and I don't see how I got the 109. You are correct, it is 100. Pretty close, but still. Thanks.

Posted by: alan2102 at April 6th, 2021 2:59 PM

[I thought that maybe this site does not allow URLs in comments, hence the "DOT com" thing, which allowed my comment to be posted. Funny however that the vitacost link went thru. ???]

Jack: I use bulksupplements DOT com for most nutrients. Odds and ends (e.g. vitamin D caps, vitamin E caps) from There's also hardrhino (now with new name, hrsupplements), which has selection and prices similar to bulksupplements. I prefer the latter only slightly.
Two grams of NAC is a significant dose. That is right in line with most clinical studies on NAC; as I said, popular dose seems to be 600 mgs QID (2.4 grams per day). I personally take 2-3 grams most days. Maybe higher would be better? Maybe.
Again: taurine is probably a safer way of getting more sulfur, and it also increases glutathione. Personally I crank 3-5 grams per day of taurine. I'm a fan. :-)
There's also MSM (methylsulfonylmethane) as a sulfur source; it has its own unique actions and advantages. I am not taking it currently but will probably go back on. Several grams daily. No direct evidence of glutathione increase with MSM, but I would expect most organic sulfurs to spare cysteine, making more available for GSH synthesis. That is the probable mechanism of taurine in elevating GSH.

Posted by: alan2102 at April 6th, 2021 3:33 PM

Can someone tell me why we should take these high dose controversial precursors when actual glutathione is available? My understanding is that the previous absorption problem was solved by the advent of sublingual liposomal glutathione.

Posted by: August33 at April 6th, 2021 9:53 PM

Oral supplementation with liposomal glutathione elevates body stores of glutathione and markers of immune function

Of course research on the use of glutathione supplements is fairly limited, see above for some evidence that glutathione may offer certain benefits when taken in supplement form. But the benefits could be due to the increase in L-cysteine as glutathione is digested into its amino acids, so maybe NAC is better? This needs to be worked out.

I'm also reading that when NAC is given along with vitamin C and glutathione, the results have been more striking than when any of these substances is given alone.

Posted by: august33 at April 6th, 2021 11:02 PM

@alan2102 - Thanks!
I use primarily Vitacost these days, and some supplements of well known brands off amazon. Also other vendors intermittently for specific items.
I've taken 3 grams MSM daily for years, taking Taurine intermittently - will look into more consistent supplementation......
I've been branching out into ayurvedic herbs and phyto supplements more recently - astragalus, rhodiola, bacopa, ashwagandha, astaxanthin.......
Are you based in the U.S.? I'm in the northeast - might be interesting to develop a blog to discuss these options and present new research........

Posted by: Jack Crain at April 7th, 2021 10:39 AM

Hello, august33!

Yes, preformed glutathione is cool. Expensive, but cool. Go for it.

I take glycine and glutamine for the (long!) laundry-list of benefits that are not necessarily attributable to their roles as GSH precursors, as well as for their role in GSH formation. For that matter, NAC as well, though in that case most bennies are probably GSH-related.

EVERYTHING is better given with vitamin C and niacin. They are the fundaments of a no-brainer orthomolecular better-health stack. IMO. They upregulate GSH synthesis, but have scores of other benefits as well. And ultra-cheap, which I love! I love the idea that we can drastically improve health, and prevent and even treat most diseases, with stuff that literally anyone on earth can afford, even people scraping by on two bucks a day.

Latest news, which I became aware of just last night: high-dose niacin cleans fat out of the liver! This is a massive society-wide problem: non-alcoholic fatty liver, or NAFL. Most people have some degree of it, esp with age, higher BMI, alcohol, fructose, etc. Looks like high-dose niacin half-cures it. (For the other half, we'll have to stop eating Pop-Tarts. Bummer, I know.) Add to this pronounced renal protection, cardiovascular protection, neurological protection, and so on, and even probable covid-19 protection. Mega-niacin is a no-brainer.

read all about it:
Archives of Gastroenterology Research (2020) Volume 1, Issue 3
Pharmacologic Therapy with Niacin for Nonalcoholic Fatty Liver Disease (NAFLD): Emerging Evidence

I know I just strayed far off topic, but I could not resist. So sue me. :-)

Posted by: alan2102 at April 8th, 2021 9:51 AM

Hi, Jack! I'm in SE Michigan. Yes, a blog. I've been telling myself I should do that for years, but I always back away because I know, given my OCD tendencies, that I would spend a huge amount of time on it, time which would come from other things that are more important at present. That situation could change however, as early as late this year. Depends on fate of investments and such. I anticipate being free for a project like that within the next few years.

Posted by: alan2102 at April 8th, 2021 9:57 AM

>Authors of the article insisted on the absurdly obscure quantitative signifier "mmol"

I think if you find mmol to be "absurdly obscure" it would be well worth brushing up on fundamentals of biochemistry. Lehninger Principles of Biochemistry is quite a good book and was used in a few of my classes at uni. There are also a couple courses on edX from Harvard and MIT which should give a good foundation.

Posted by: J C at April 11th, 2021 9:14 PM


From this paper:
(Hat tip to the youtube video by Michael Lustgarten, Ph.D. )

Although Glycine and Cysteine are lower in older adults, Glutamate is not. Perhaps that is why they only supplemented with Glycine and Cysteine.

Part of table 2 (Forgive the formatting.)
Younger Older
Glycine (μmol/L) 486.7 ± 28.32 218.0 ± 23.73
Cysteine (μmol/L) 26.2 ± 1.44 19.8 ± 1.35
Glutamate (μmol/L) 463.1 ± 69.0 464.0 ± 115.3

Posted by: Albert at April 12th, 2021 8:41 AM

Hi, JC!
For the reader who wants to understand easily, and make practical use of what is being described, "mmol" is absurdly obscure and totally unnecessary, IMO. Fuck "mmom". Just give the god damn milligram amounts. That is, rather than forcing the reader to consult obscure textbooks like Lehninger's. Yes, we can consult those textbooks, or look up MW on google and calculate, but why the hell should we have to? It is like writing the abstract in Latin, and insisting that the abstract can be read by just simply easily effortlessly consulting a Latin grammar and vocabulary text. WTF? It amounts to elitist, obscurantist bullshit, sorry. Totally unnecessary; serves NO worthwhile purpose.

Posted by: alan2102 at April 12th, 2021 10:26 AM

Hi, Albert!
A few thoughts on this.
1 Glutamate is not glutamine. Glutamine is a quite versatile amino acid with many benefits, not least providing a nice bit of kidney-sparing (and generally salutary) alkali. Favorable effects on: liver regeneration, gut integrity, glucose disposal, gut microbiota, etc. In addition to acting as glutathione precursor.
2 That glutamate levels were no different in young v. old does not tell us anything about what amounts might be optimal (and optimality itself has to be defined in terms of given objectives or desired outcomes)
3 Glutamine acts effectively as glutathione precursor: PMIDs: 12850466, 17569119, 18313901, 10696636, 9661123
4 Glutamine incidentally acts indirectly as a glycine precursor, and this has been suggested as reason ("replenishing the glycine pool") for its effect on GSH: PMID: 22261571
I personally take glutamine for many reasons, not only GSH boost.

Posted by: alan2102 at April 12th, 2021 11:07 AM

JC: "mmom", meant "mmol", of course.

Posted by: alan2102 at April 12th, 2021 11:08 AM


Thanks for the response. I make no claims as to what is best since I'm not an expert. Since I don't have access to the authors of the paper, I'm just trying to guess why they chose the combination they did. No idea why they picked such a high level of NAC though.

Posted by: Albert at April 12th, 2021 12:34 PM

I would be interested on comments on this paper. The use of Glynac would seem to be one of the best options for combating inflammation. I personally quit taking it when I read this paper:

But I have seen no comments on this paper and wonder if further information is availble.

Posted by: DRG at March 17th, 2022 1:07 PM
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