Why is it that at the same age of 30, some people look like they are in their early 20s while others look older than their actual age?

In fact, apart from daily maintenance such as exercise and diet, ageing is also largely related to telomeres.

What are telomeres?

On 5 October 2009, the Karolinska Institute of Medicine in Sweden announced that it had awarded the 2009 Nobel Prize in Medicine to three American scientists, Elisabeth Blackburn, Carole Greider and Jack Shostak.

Three scientists have discovered that telomeres are fundamental to a long and healthy life and are known as the 'life clock'. There is a limit to cell division, known as the Hayflick limit, and after a certain number of divisions, the telomeres become too short and the cell stops dividing and gradually ages and dies. Telomere length has been shown to be an important marker of ageing, with telomere length wearing off and shortening with age, and maintaining telomere stability is considered to be one of the most important means of counteracting ageing.


The shorter the telomere, the higher the mortality rate from disease. Telomere length can have an impact on how well the skin ages, how well the heart and lungs function, how well the bones are doing, and even how well a person can cognitively function.

When a person is born they have 10,000 base pairs on their telomeres, but by the age of 35 they have only 7,500 base pairs and by the age of 60 they have only 4,800 base pairs.

This feeling gives a sense of fatalism: the length of telomeres at birth determines our life expectancy. So, is there a way to slow down telomere shortening?

The answer is yes.

Telomeres and NAD+

Nicotinamide adenine dinucleotide (NAD+) supplementation has been found to reduce telomeric DNA and mitochondrial damage, restore Sirtuin (longevity factor) and PARP (DNA repair enzyme) activity, and delay a range of aging problems caused by short telomeres, including cellular senescence in patients with congenital keratosis.

However, the activity and content of NAD+ decreases significantly from the age of 30, leaving only a quarter of it by the age of 60.The inevitable occurrence of this process determines and accelerates the ageing of the body. The timely and targeted replenishment of the body with NAD+ to counteract this loss is considered to be the key to inhibiting ageing.

However, the large molecular weight of NAD+ does not allow it to be replenished by penetrating the cell membrane from outside the cell. However, NAD+ levels can be increased by supplementing with the NAD+ precursor NMN.

As the main raw material for NAD+ synthesis, NMN is a small molecule that can be effectively absorbed by the body's cells and can quickly penetrate cell membranes, thus promoting the natural synthesis of NAD+, stabilising the cell's DNA structure, slowing down the rate of telomere shortening and slowing down ageing.

In addition, some animal studies have shown that NMN supplementation can help maintain telomere length, inhibit the DNA damage response and improve mitochondrial function, thereby treating diseases such as liver fibrosis that are closely related to telomere shortening.

The above results are from a multi-institutional study in which the "telomere clock" was successfully reversed using NMN. The experimental results are as follows:

1. NMN doubled telomere length in humans over a 90-day period.

2. Giving NMN to mice also reduced the diversity of bacterial species in the microbiome.

Analysis of the literature:

1. NMN boosts metabolism in mice

To determine the benefits of NMN in mice, researchers measured body heat output (heat output is a biomarker and bioindicator of metabolism).

Assessment of metabolism by body heat showed that NMN administration increased caloric output by approximately 10% over a 40 week period, confirming that the NMN improved metabolic function.

2. NMN alters intestinal bacterial diversity

Intestinal bacterial health is a biomarker of overall physiological health. Researchers have observed that short-term NMN administration reduces the diversity of bacterial species in the gut.

Notably, several healthy gut-associated bacterial species were abundant, such as Mucor spiralis, Escherichia coli and Saccharomyces cerevisiae. On the other hand, there was a decrease in the prevalence of common age-related bacteria such as Staphylococcus, Corynebacterium and human alkaloid-producing bacteria.

3. Oral administration of NMN drives telomere elongation

The researchers divided 20 16-month-old male pre-aging mice (equivalent to 45-55 years old in humans) into 2 groups and fed one group with NMN-containing water. The overall duration was 40 days and the telomere length of the mice in the NMN group was significantly different from that of the control mice as measured by PCR, with a 20-25% increase in telomere length with a short period of NMN.

Meanwhile, the investigators recruited a total of eight healthy male volunteers aged 45-60 years and subjected them to a non-blinded clinical trial. All participating volunteers were asked to take NMN (300 mg/day/person) in warm water 30 minutes after breakfast every day for a total of 90 days.

Ultimately, the researchers found that oral NMN supplementation doubled telomere length in human blood cells from peripheral blood mononuclear cells (PBMC) within 90 days, and reached an average of nearly twice the length before the trial began after 90 days.

Evidence gathered from this study suggests that NMN can improve gut microbial composition in mice and telomere length in both mice and humans, effects that may significantly improve healthy lifespan.

Whether or not NMN extends lifespan, the findings suggest that it may help people live longer years of healthy and happy lives.