March 3, 2026, 10:03 am | Read time: 5 minutes

What Did the Study Examine?

For the review published in the journal “Aging Cell,” researchers from Hainan Medical University and Peking University evaluated numerous studies on laboratory organisms such as nematodes and fruit flies, on mice, as well as the data available on humans.¹ The goal was to provide an overview of the current state of research.

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The Results

The study shows that several of these substances can intervene in age-related biological processes in experimental model systems. The effects vary greatly depending on the organism and study context. Here is a selection of the substances considered:

Taurine

This endogenous substance supports nerves and mitochondria, among other things. In certain animal models, there were indications of reduced cell damage and functional improvements in specific tissues. However, results in humans are contradictory. A clear link between taurine and healthy aging has not yet been definitively established.

Betaine (TMG)

This substance plays a role in cell protection and the regulation of gene activity. In nematodes, betaine extended lifespan, and in mice, it improved muscle strength, endurance, and inflammation markers. For humans, the data is currently limited and inconsistent. Some studies also suggest that high doses of betaine, in the range of several grams per day, can adversely affect blood lipid levels.

Alpha-Ketoglutarate

This is a central intermediate in energy metabolism. In nematodes, alpha-ketoglutarate significantly extended lifespan, and in mice, it showed a measurable extension of lifespan and health span. Possible explanations include changes in cellular energy metabolism and enhanced cellular self-cleaning (autophagy). Very limited data is available for humans, and a confirmed effect on aging is not established.

Ketone Bodies

They serve as an alternative energy source for the body during fasting. In worms, they extended lifespan. In mice, the results were mixed: While ketogenic diets improved health under certain conditions, they led to increased mortality in other experiments–such as with early or consistently strict application. There is currently no solid evidence that ketone bodies or ketogenic diets slow aging or extend lifespan in humans.

Myo-Inositol

This vitamin-like compound is important for cell communication. In worm studies, an extended lifespan was observed. In mouse models, there are indirect indications of cellular protective mechanisms and improved organ function. However, its significance for human aging is currently unclear.

NAD+

This is a central substance for cellular energy production. NAD+ levels decrease with age. In animal studies, the administration of NAD+ precursors like NMN or NR led to improvements in metabolic and performance parameters. Human studies have so far shown mixed results and no confirmed impact on lifespan. Researchers also caution that potential long-term risks have not yet been ruled out.

Methionine (or Methionine Restriction)

This essential amino acid is obtained exclusively through diet and is mainly found in animal products such as meat, fish, eggs, and cheese. In various animal models, a targeted reduction in methionine content–with otherwise sufficient calorie and nutrient intake–extended lifespan. For humans, there are currently no reliable long-term studies to assess benefits and potential risks.

Branched-Chain Amino Acids

These so-called BCAAs are important building blocks of muscle protein. Their effect on aging is contradictory: In some studies, they supported muscle and energy balance, while a consistently high intake in other studies was associated with metabolic disorders, inflammatory changes, and other age-related problems.

Vitamins

In animal models, certain vitamins–especially Vitamin D3, Vitamin C, and Vitamin B12–showed some life-extending or protective effects. Large human studies, however, mostly found little or no clear influence on age-related physical functions or the occurrence of diseases.

Spermidine

This substance activates autophagy or cellular self-cleaning. An extended lifespan was observed in several animal species. In humans, corresponding indications are primarily based on observational studies and are not considered definitively proven.

The authors explicitly emphasize that this is an inventory of current research. Many of the substances described are considered biologically interesting, but for most, there are still no meaningful long-term studies in humans. Whether and for whom this actually results in a benefit must be clarified through further research.

What Does the Study Mean?

Aging is not controlled by a single substance but by a complex interplay of many biological processes. Several of the substances studied intervene here and are therefore relevant for research. At the same time, the authors clearly emphasize that results from worms, flies, or mice do not constitute proof of life extension in humans. There is a particular lack of long-term studies on efficacy, optimal dosage, and safety.

Important: The study provides a scientific classification and not a recommendation for intake or self-treatment.

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