Can You Rebuild Glutathione After 60? The Result of This Trial Are Amazing!

Written by David Roberts, MPH, Co-founder, Mara Labs

Two things show up in nearly every list of what goes wrong in an aging cell: oxidative stress climbing, and mitochondria working less optimally.

Both are difficult to change. A 2023 trial tried to change them with two cheap amino compounds, and the results are important to understand.

What is glutathione, and why does it fall with age?

Glutathione is a small molecule your cells build themselves, and it is the main antioxidant working inside the cell rather than coming from food.

It is made from three amino acids: glutamate, cysteine, and glycine. Your body assembles it continuously, and the supply depends on two factors: having the raw materials and having a working assembly line.

These levels drop with age. That decline is one of the better-documented biochemical changes in older adults, and it tracks alongside rising oxidative stress.

The question is whether it can be reversed, and whether reversing it changes anything a person would notice.

What did the trial test, and in whom?

It gave older adults the two amino acids most likely to be limited, and measured what happened over four months.

The study was a double-blind, placebo-controlled randomized trial published in January 2023 in The Journals of Gerontology, registered as NCT01870193. [1]

Twenty-four adults aged 61 to 80 were randomized. Twelve received glycine and N-acetylcysteine, abbreviated GlyNAC, at 100 mg per kilogram of body weight per day.

Twelve received an alanine placebo at 200 mg per kilogram per day, and took their assigned regimen for 16 weeks.

A separate, non-randomized group of 12 young adults took GlyNAC for 2 weeks as a comparison point.

What happened to glutathione and oxidative stress?

Both glutathione and oxidative stress moved substantially, and in the direction the researchers predicted.

The oxidative stress figure covers two separate markers, TBARS and F2-isoprostanes, which both fell by about the same amount. [1]

The phrase worth noticing is "no longer different from young adults." After 16 weeks, these two markers in the older group had moved into the range of the young-adult comparison group.

That is a statement about two specific measurements, not a statement about being younger.

Mitochondrial measurements also improved, including fatty acid oxidation and the normalization of glucose oxidation. [1]

Did anything change that a person would feel?

Several physical measurements improved, which is the part that separates this trial from a purely biochemical result.

Gait speed and chair-rise time are not vanity metrics. Geriatricians use both as predictors of independence, and a chair-rise time falling by almost seven seconds is a large change.

Why glycine and N-acetylcysteine rather than glutathione itself?

Glutathione taken by mouth is poorly absorbed, so the practical route is to supply what the body builds it from.

N-acetylcysteine delivers cysteine, typically the limiting amino acid. Glycine supplies the third. Glutamate is rarely in short supply. Giving the two scarce inputs is the logic behind the intervention.

There is a second lever on the same pathway, working from the other end.

The enzyme that performs the rate-limiting step in glutathione assembly is itself switched on by Nrf2, the transcription factor governing the cell's defensive gene program. [3] [4]

So there are two ways to make more glutathione: more raw material, or more assembly capacity.

Sulforaphane is among the better-studied Nrf2 activators, and the precursor make-up of most sulforaphane supplements is the main limiting factor in Nrf2 activation.

The GlyNAC trial tested the raw-material route, but does not address the Nrf2 activation arm of the process.

What are the limits of this study?

Twelve people per arm. That is small. This trial was the placebo-controlled follow-up to a 2021 open-label pilot by the same group. [5]

That is the right sequence, but 24 randomized participants is a starting point rather than a settled result.

The dose was a clinical protocol. A 70 kilogram adult took roughly 7 grams of glycine and 7 grams of N-acetylcysteine daily, under medical supervision, for four months.

That is not a typical consumer serving size.

N-acetylcysteine has a contested regulatory status. The FDA's position is that NAC is excluded from the dietary supplement definition, because it was approved as a drug first. [6]

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