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Harold Katcher’s E5/Elixir (Young Plasma) Rat Trial Results

Harold Katcher’s Yuvan Research is currently running an experiment to see the impact of regular injections of its E5 “elixir” in laboratory rats. Based on updates in newsletters, the Live Forever Club is tracking the result of the experiment as it (or some sort of blood plasma therapy) is one of the leading contenders of a clinical treatment for humans in the near future.


In 2020, Katcher published the results of an experiment in which he injected 2-year-old rats with a plasma fraction (components of blood) from younger rats and monitored its effects. In summary, as well as an average epigenetic age reduction of 54% (across a variety of tissues), the old rats had more youthful levels of over 20 biomarkers and, also, displayed improved physical strength and cognitive ability. More details available in a blog feature at the time - Age Reversal in Mammals – Has This Now Been Achieved? 

The only big question not answered in that experiment, was did the improvement is so many biological ageing clocks have a real impact of lifespan? As all of the rats were sacrificed to study their tissues, this was not determined, but that is about to change.

Experiment Details

To answer the question of whether average lifespan (i.e. life expectancy) or, even better, maximum lifespan improves as well as the healthspan of the rats, Katcher started a new experiment in February 2021. As before, it began with 24-month-old laboratory rats (female Sprague Dawley rats).

Once the rats die they are being frozen for future examination including analysis of biomarkers in different organs.  As of the early May 2022 update, the dead rats showed no obvious symptoms of cause of death.

Survival Curve

In longevity experiments the survival curve shows how long the subjects (rats, flies, humans) lived for – ignoring health or any other biomarker data. If we’re going to be able to live significantly longer (or indefinite) lives, then this this where we want to see improvements.

Here is the survival curve of two breeds of popular laboratory rats:

It shows that, typically, rats don’t start to die until they are one year old (up until then, 100% have survived), then there is a steady loss until the deaths increase rapidly at about two years old. This is the same exponential increase of mortality with age as seen in humans and most mammals. A few outliers buck the curve, but there are no survivors beyond around three years – the maximum lifespan of these animals. However, the exact strain of the rats, and their living conditions, will affect the results, and therefore laboratory experiments to use a control group of rats, of the same strain and in the same conditions, to compare against the treated rats.

In many studies, the average lifespan increases which pushes the bulk of the curve to the right, but often the maximum lifespan does not increase so the graph still hits 0% at around the same time. This is not a bad result, as that is often representative of compressed morbidity, that is, a longer period in good health followed by a shorter period of time suffering the consequences of ageing.

In Katcher’s E5 study, the question is whether the biological age improvements seen in the previous experiment result in actual longer lives – it will be disappointing if the average lifespan doesn’t increase. The excitement will come if maximum lifespan is also increased.

Updates on the experiment are being provided ad hoc, so the survival curve below is a slight approximation as I’m using the newsletter date for date of death (unless otherwise provided), and nor do I know the exact day in February 2021 that the experiment started – but it should give a good indication of how things are going until the final results are published.


Yuvan Research is releasing some results as the trial progresses, including:

  • body weight
  • grip strength
  • IL-6
  • TNF-alpha

Sometimes they are snapshots (point in time) and sometimes a full history is provided.

During an update video, Dr. Katcher suggested they are seeing 15-20% reduction in age which is less than the effect seen in the original study. He believes this may be because this experiment is using all female rats, whereas the original study used all male rats.

Body Weight

Time series last updated January 2022 (rats aged 36 months):

Harold Katcher Elixir trial - body weight

No update since.

Grip Strength

At 38 months, the surviving treated rats had a grip strength (4.3 N) of over double that of the surviving control old rats (11.1 N).

Time series last updated January 2022 (rats aged 36 months):

Harold Katcher Elixir trial - grip strength


Time series last updated January 2022 (rats aged 36 months):

Harold Katcher Elixir trial - IL-6

No update since.


In May 2022, Dr. Katcher posted a photo of his hands - three days after he rubbed some E5 on his right hand. He claims the skin was visibly thicker and lighter, and generally looks decades younger. Decide for yourself...

Harold Katcher Elixir trial - skin test result


Time series last updated January 2022 (rats aged 36 months):

Harold Katcher Elixir trial - TNF-alpha

No update since.


Grip strength test and Harold's comments on E5 lifespan study - Yuvan Research (YouTube) - 03-May-2022

Reversing age: dual species measurement of epigenetic age with a single clock - bioRxiv - Harold Katcher, Steve Horvath et al., 2020

Within- And Between-Strain Variability In Longevity Of Inbred And Outbred Rats Under The Same Environmental Conditions – Experimental Gerontology - Institute for Research on Senescence - Giuliani et al, 1995


The main text is updated as new information is received, including:

03-May-2022: update on impact of rats' sex, and photo of Katcher's hands after E5 application (from Yuvan Research video)

02-May-2022: update on number of rats surviving (from NTZ newsletter)

Mentioned in this blog post:

Tap on icon for description, click on resource name for more details.


Professor at University of Maryland - working on rejuvenation blood factors


US arm of Harold Katcher's young plasma research

TruDiagnostic TruAge Biological Age Test Review

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