Vitamin C Re-evaluated: A Direct Inhibitor of the 'Ferro-Aging' Clock

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#21

Follow-on Prompt:

How was the vitamin C in this study delivered to the monkeys, what is the half-life of vitamin C in the blood, and would regular vitamin C or extended release vitamin C be better for the purposes of countering Ferro-aging?

Google Gemini 3 Pro Response:

Study Delivery Mechanism

In the 2026 Cell Metabolism study, the aged cynomolgus monkeys in the intervention cohort (O-VC) were administered vitamin C orally at a dose of 30 mg/kg/day. This was delivered specifically via their drinking water, provided post-breakfast, and the protocol was sustained continuously for 40 months.

Pharmacokinetics and Half-Life

The half-life of vitamin C (ascorbic acid) in human blood is non-linear and highly dose-dependent, governed primarily by renal threshold dynamics and saturable active transport (SVCT1 and SVCT2 receptors).

  • Baseline/Deficiency: At sub-saturating plasma concentrations (below approximately 70 μM), renal reabsorption is highly efficient, extending the biological half-life to 10–20 days.
  • Pharmacological Dosing: When administered at high, saturating oral doses (e.g., 500 mg and above), absorption decreases, and the renal threshold is rapidly exceeded. The excess ascorbic acid is cleared rapidly, exhibiting a functional half-life of approximately 30 minutes to 2 hours.

Regular vs. Extended-Release for Ferro-Aging

For the specific objective of countering ferro-aging via the structural inhibition of the ACSL4 enzyme, extended-release (sustained-release) formulations offer a stronger theoretical and pharmacological advantage.

To provide actionable insights for longevity protocols, we must evaluate this through the lens of enzyme kinetics rather than general antioxidant quenching.

  1. Target Engagement: Effective enzyme inhibition requires maintaining the inhibitor concentration above a specific threshold (the IC50​) at the target site. Immediate-release vitamin C creates a rapid, transient spike in plasma concentration followed by swift renal excretion, leaving target tissues vulnerable to uninhibited ACSL4 activity for the remainder of the day.
  2. Steady-State Saturation: Extended-release formulations delay gastrointestinal transit and absorption, flattening the peak (Cmax​) but sustaining an elevated baseline concentration over a 12-to-24-hour period. This continuous delivery model is more likely to maintain constant occupancy of the ACSL4 catalytic pocket (residues Thr278, Ser279, and Thr469), thereby preventing the thioesterification of polyunsaturated fatty acids and subsequent lipid peroxidation.
  3. Toxicity Mitigation: Extended-release formulations avoid extreme plasma peaks, which may marginally reduce the acute spike in urinary oxalate excretion, lowering the risk of calcium oxalate nephropathy associated with high-bolus dosing.

Identified Knowledge Gap: We currently lack human in vivo pharmacokinetic data defining the exact intracellular concentration of vitamin C required to outcompete endogenous arachidonic acid for the ACSL4 binding pocket. Until that IC50​ is established clinically, maintaining a stable, elevated steady-state via extended-release dosing or divided daily dosing is the most practical pharmacological strategy.

#22

All of this information deserves careful consideration but my sense, taking it all in, is that the final chapter is yet to be written on vitamin C. I do not believe in generalizing from N=1 but I can apply such data to myself. At the least, given that most of my age-related metrics fall in the -20 years range and (knock, knock) I have yet to have a major (or even a minor, really) illness or disease, it seems reasonable to think that six decades of vitamin C – never missing a day – has not harmed me in any way that I can discern. Perhaps it has and it will show up when I’m 90. :slight_smile:

I note that some of the negative theoretical data on vitamin C is contaminated with the co-administration of other substances such as alpha tocopherols.

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#23

Plasma peaks don’t really reflect intracellular Vitamin C levels. Once ascorbate enters the cell, it stays there much longer than it does in the bloodstream.

On the other hand, it’s not simply a matter of finding the ‘best’ formula.The study used standard oral vitamin C. Changing the form could also alter the kinetics, and there is no guarantee that the same effect will be achieved.

Calcium Ascorbate has better gastric tolerance than Ascorbic Acid.

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#24

My only real concern with Vit C is oxalate stones. Other than that it has always looked very promising.

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#25

Yes. oxalate stones are definitely a risk if you are susceptible. I am fortunate to have learned that I am not. Even if susceptible, staying on the upper bound of hydration and never allowing yourself to be dehydrated is the primary and most effective method for preventing kidney stones. Formation is a possible consequence of underhydration.

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#26

FWIW…

Use oral liposomal vitamin C much higher bioavailability

I have not done IV in a long time, use to do very high, 50gram{yes grams) on the low end and more per infusion.

#27

I don’t know if this was good advice, but after Claude AI examined my labs and told me I should take a vit C supplement, in looking for low dose, ‘he’ suggested acerola powder so I could just add a smidge to my other powders.

I haven’t done this yet, but plan to

1 Like
#28

Were you treating a specific issue @Joseph?

#29

No, just for health.

Also did O²/O³ via MAHT countless times

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#30

Does anyone have access to the paper to see how the vitamin C was dosed for the monkeys? I am wondering if the Vitamin C was given in one dose, or spread throughout the day mixed with standardized chow of some sort.

I have some personal indication that Vitamin C acts differently when dosed throughout the day. Obviously this is incredibly anecdotal, and I only mention it because so often, the practical applications only are understood that way for off-label uses that do not get research funding.

I have long-term problems with dysautonomia and have tried a lot of approaches to optimize my health, including nutritional supplementation, but mostly relying on academic research. In my own personal experience, most of the things sold as supplements are ineffective and have no effect that I can notice.

I live in a small town, and was talking to someone I know who was working in the health food store, and it turned out that she also had developed some of the same problems that I had following an infection. She claimed that she had seen significant improvement from taking Vitamin C powder throughout the day.

This didn’t strike me as being particularly likely, and I suspected a placebo effect due to the strong flavor, but I threw this into a set of four experimental interventions that I was going to try for a month as a gap filler, for lack of any better option during that period. The Vitamin C powder was so obnoxious that I took several (much higher dose) pills instead.

I saw improvement from that month’s intervention with my dysautonomia symptoms (not a cure, but still), and expected that the cause was one of the other supplements, but my elimination experiments kept pointing back to the Vitamin C. Taking a big single or twice a day megadose didn’t provide the same benefits (indeed any benefits that I could notice) as doses spread throughout the day (at least four doses, better six).

I have tried cutting the dose way down from the large amount that I was on using pills, and frankly, I recommend using small pills and then splitting them, or taking Vitamin C powder if you can stand it, because otherwise, such frequent dosing alters your urinary habits and fluid balance.

My specific circumstances with dysautonomia are hardly universal, but this example might still be relevant because of the way that Vitamin C is typically eliminated rapidly in the body.

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#31

See the summary above (or do you need more information?):

In the 2026 Cell Metabolism study, the aged cynomolgus monkeys in the intervention cohort (O-VC) were administered vitamin C orally at a dose of 30 mg/kg/day. This was delivered specifically via their drinking water, provided post-breakfast , and the protocol was sustained continuously for 40 months.

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#32

Yes, of course that makes sense. That’s how we get vit. C in the diet. We don’t get it in one big bolus. If you take it in one big pill, you will mostly pee it out and you’re asking for kidney issues to boot. The body can absorb about 250mg at once, not much more. This is why I kept searching for low vit. C pills not the monster 1g or 500mg ones - it is shockingly hard to get. I found two brands of 100mg tabs. I could do powder, but I already take so many powders a day, I just don’t feel like adding yet more. Right now I’m on a bone building protocol following ACDF surgery, so I’ve upped my vit. C intake. Currently I supplement with 100mg twice a day (so 200mg for the day), one with breakfast, one with dinner. Ordinarily - when not on some protocol like right now - I supplement vit. C very sparingly, 100mg three times a week, that’s it. Just topping it off. But I take a lot in through diet, every day: berries, fruit including citrus (with peel!), veggies. The body can use about 500mg a day before tissues become saturated. I think - unless you have some condition or are on some protocol - about 250-300mg a day of vit. C total (from diet and supps) is where you want to land. YMMV.

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#33

Aging and the Antioxidant Paradox

My thoughts (And with a lot of help from Claude) and also why I think GlyNac is a very interesting supplement.

In the young athlete, the endogenous system is self-correcting — exogenous antioxidants are largely redundant and can even interfere with the feedback signals the body uses to improve itself.
In the aged individual, the self-correcting mechanism is broken. The redox state has shifted to a new, dysfunctional equilibrium that the endogenous system can no longer pull back from on its own. This is precisely the context where supporting antioxidant status from outside — through diet, targeted supplementation — has genuine biological rationale. The goal is not to suppress ROS signaling, but to restore the system’s ability to regulate itself.

ROS Accumulate With Age

Several converging mechanisms drive ROS accumulation as we get older:

  • Mitochondrial dysfunction: Mitochondria become less efficient with age. Their membranes deteriorate, electron transport chain complexes become damaged, and electron leakage — and thus ROS production — increases substantially.
  • Impaired antioxidant defenses: The body’s endogenous antioxidant enzymes — superoxide dismutase (SOD), catalase, and glutathione peroxidase — decline in expression and activity with age.
  • Accumulation of damaged macromolecules: ROS oxidize proteins, lipids, and DNA. With age, the cellular “cleanup” systems (proteasome, autophagy) become less efficient, meaning oxidatively damaged material accumulates and itself becomes a source of further oxidative stress — a vicious cycle.
  • Chronic low-grade inflammation (“inflammaging”): Aged immune cells produce more pro-inflammatory cytokines, which in turn stimulate ROS production via NADPH oxidases.
  • Reduced NAD⁺ levels: NAD⁺ is critical for mitochondrial function and for activating sirtuins (stress-response proteins). NAD⁺ levels fall sharply with age, further impairing the cell’s ability to manage oxidative stress.

The net result is a shift in redox balance toward a chronically pro-oxidant state — a hallmark of biological aging sometimes called oxidative stress.

The Youth Paradox: Why Antioxidants Can Be Harmful in Young, Healthy Individuals

In a young, healthy organism, ROS levels are tightly regulated and purposefully low. Here, ROS act as essential messengers. Suppressing them with exogenous antioxidants can interfere with:

  • Exercise adaptation: Physical exercise deliberately generates ROS, which signal muscles to upregulate mitochondrial biogenesis, improve insulin sensitivity, and become stronger. Studies (notably by Ristow et al., 2009) showed that high-dose vitamins C and E blunted these adaptations in young exercising humans — they prevented the very stress signal that drives fitness gains.
  • Hormesis: The principle of hormesis holds that a mild stressor (like moderate ROS) produces a disproportionately beneficial adaptive response. Over-suppressing this signal removes a key driver of cellular resilience.
  • Immune function: ROS are weaponized by immune cells (e.g., the “oxidative burst” of neutrophils) to kill pathogens. Excessive antioxidant supplementation can dampen this response.
  • Redox signaling pathways: Pathways like Nrf2, NF-κB, and MAPK rely on controlled ROS fluctuations. Blunting these signals can paradoxically impair the cell’s own long-term antioxidant gene expression.

In short, in young individuals, the body’s endogenous antioxidant systems are well-matched to ROS production. Adding more antioxidants from outside tips the balance into reductive stress — which is its own form of dysfunction.

Old Age: When the Balance Tips and Antioxidants Help

In an aged organism, the situation is fundamentally different. The chronic overproduction of ROS now exceeds the cell’s capacity to neutralize them, and the damage is cumulative and widespread:

  • Oxidative DNA damage contributes to mutations and genomic instability
  • Lipid peroxidation degrades cell membranes and produces toxic aldehydes (like 4-HNE and MDA)
  • Protein carbonylation leads to loss of enzyme function and structural protein integrity
  • Mitochondrial DNA damage further worsens energy production, feeding the cycle

Here, supplementing antioxidant capacity — whether through diet or targeted compounds which delivers antioxidants specifically to mitochondria — can help restore a more balanced redox state, rather than suppressing a beneficial signal. The goal isn’t to eliminate ROS, but to bring chronically elevated oxidative stress back into a physiologically useful range.

Summary: Context Is Everything

Young & Healthy Aged
Baseline ROS level Low–moderate, tightly regulated Chronically elevated
Endogenous defenses Robust Declining
ROS role Signaling, adaptation, immunity Primarily damage
Antioxidant supplementation Can blunt adaptation (harmful) Can restore redox balance (beneficial)
Key risk Reductive stress, impaired hormesis Oxidative stress, cumulative damage

This is why blanket recommendations like “everyone should take antioxidant supplements” are too simplistic. The redox context of the individual — heavily shaped by age — determines whether adding exogenous antioxidants is a benefit or a hindrance. A young athlete taking high-dose vitamin C might be undermining their training; an 70-year-old with mitochondrial dysfunction might genuinely benefit from carefully targeted antioxidant support.

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#34

As @RapAdmin posted earlier
Half-Life of Oral Vitamin C

  • Blood Plasma Half-Life: Once in the bloodstream, the half-life is typically 30 minutes to 2 hours. Because Vitamin C is water-soluble, your body maintains tight control; at high doses (over 1 gram), any amount that exceeds the body’s immediate needs is filtered by the kidneys and excreted in urine within a few hours.
  • Tissue Half-Life: While it leaves the blood quickly, Vitamin C stored in your tissues (like the brain and adrenal glands) has a much longer half-life of 10 to 20 days. This provides a buffer that prevents immediate deficiency.

Are you suggesting that you only get relief while vitamin C is in your plasma?

Vitamin C is primarily transported in the blood plasma.

  • Form: It circulates as the ascorbate monoanion (the reduced form of ascorbic acid) and is not bound to any transport proteins.
  • Concentration: In healthy adults, plasma levels are relatively low, typically ranging from 40 to 80 µM. Because it is water-soluble, plasma levels are the first to rise after you take a supplement and the first to fall as the vitamin is excreted or absorbed by tissues.

In the Blood Cells

Vitamin C also enters the various cellular components of your blood, often at much higher concentrations than in the plasma.

  • White Blood Cells (Leukocytes): These cells maintain the highest concentrations in the blood, often 30 to 80 times higher than plasma levels. They use active transport to “pump” the vitamin inside, where it acts as a long-term reservoir that is less affected by daily intake fluctuations.
  • Red Blood Cells (Erythrocytes): Unlike white blood cells, red blood cells do not have specialized active transporters for Vitamin C. They take up the oxidized form (dehydroascorbic acid) through glucose transporters and quickly convert it back to the reduced form inside the cell. Their internal concentration generally mirrors the levels found in the plasma.
  • Platelets: These also concentrate Vitamin C to levels significantly higher than the surrounding plasma.

“In clinical settings, “blood vitamin C” usually refers to the plasma concentration, as this is the standard biomarker used by Mayo Clinic Laboratories and other diagnostic providers to assess your current nutritional status”

3 Likes
#35

Insightful. So what about a healthy 59 year old with a 48 y.o. phenoage, youthful hormone profile, but definitely doesn’t feel like he use to - not healing as fast, losing strength, some metabolic creep. I am trying to figure out the ideal anti-oxidant load to restore balance.