Pre-reading Tip
Summer brings stronger sunlight and increased ultraviolet (UV) radiation. This invisible light silently threatens skin health—accelerating aging, triggering inflammation, and even raising the risk of skin cancer. In recent years, with in-depth scientific research, a substance called NMN (nicotinamide mononucleotide) has gradually gained public attention. By boosting intracellular NAD+ levels, activating DNA repair pathways, and regulating antioxidant defense systems, NMN offers a new intervention strategy to mitigate UV-induced skin damage.
01 Harmful Effects of UV Radiation
- Sunburn: Long-term sun exposure impairs the skin barrier. Immune cells and vascular endothelial cells in the skin respond rapidly, releasing inflammatory factors and triggering immune reactions.
- Tanning, Dark Spots, and Red Blood Vessels: Excessive sun exposure not only darkens the skin and induces sunspots but also worsens freckles and chloasma. Chronic UV radiation damages the stratum corneum, thinning the skin and causing capillary dilation/rupture, leading to red blood vessels.
- Accelerated Aging: UV radiation breaks down collagen and elastic fibers in the skin. As these key structural supports are damaged, the skin loses elasticity, sags, and develops more wrinkles and fine lines—speeding up the aging process.
- Cancer Risk: Chronic overexposure to UV radiation damages skin cell DNA. When the cell’s repair mechanism fails, DNA may mutate, increasing the risk of skin cancer.
02 Mechanisms of NMN in Reducing UV Damage
- Enhancing DNA Repair Capacity: NMN boosts NAD+ levels to activate PARP (poly ADP-ribose polymerase). When DNA is damaged, PARP recognizes the damaged site, uses NAD+ as a substrate, and initiates a series of DNA repair reactions by transferring ADP-ribose groups to target proteins—effectively reducing UV-induced DNA damage.
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Antioxidant Effects: UV radiation generates large amounts of reactive oxygen species (ROS), triggering oxidative stress. NAD+-involved metabolic pathways regulate intracellular redox balance:
- Maintains the activity of antioxidant enzymes to enhance cellular antioxidant capacity and scavenge excess ROS.
- Regulates intracellular redox signaling pathways to sustain balance, further protecting skin cells from UV-induced oxidative damage.
- Regulating Inflammatory Responses: UV irradiation triggers skin inflammation, releasing inflammatory mediators such as interleukin-1 (IL-1) and tumor necrosis factor-α (TNF-α), which exacerbate skin damage. By increasing NAD+ levels, NMN activates Sirtuins family proteins, inhibits the activation of inflammatory signaling pathways like NF-κB, and reduces the production/release of inflammatory mediators—alleviating UV-induced skin inflammation and symptoms such as redness and pain.
- Inhibiting Ferroptosis: UV irradiation induces ferroptosis in skin cells—a process where iron ion accumulation leads to cell death via ROS attack. NMN enhances cellular antioxidant capacity by increasing NAD+ levels, reducing lipid peroxide accumulation, and thus inhibiting ferroptosis to protect skin cells from UV damage.
03 Supporting Research
In January 2022, researchers from the National Center for Translational Medicine, Fourth Military Medical University, China, demonstrated that lipid peroxide accumulation and ferroptosis cause UV-induced skin damage in mice. They found that NMN supplementation reduces iron-dependent lipid peroxidation and mitigates UV-induced skin injury (published in Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease).
In the experiment:
- Mice were shaved and exposed to high-intensity UV radiation, resulting in severe skin edema and thickening of the epidermis and dermis.
- One group received 400mg/kg NMN orally daily via drinking water for a week post-UV exposure; another group received injections of Lip-1, a potent ferroptosis inhibitor, for comparison.
- Results showed both NMN and Lip-1 significantly alleviated UV-induced skin edema in mice.
As early as March 2021, a study published in Front Pharmacol noted that NMN combined with Lactobacillus fermentum TKSN041 helps mice resist UV damage, largely by combating UV-induced oxidative stress. The Fourth Military Medical University study further confirmed that NMN alone effectively mitigates UV-induced skin damage.
04 Summary
While we debate sunscreen SPF values, science has advanced sun protection to the cellular level. NMN does not replace traditional sun protection methods but acts as a "damage control" tool after UV exposure. This summer, try combining topical sunscreen with oral NMN: physical and chemical sunscreens block most UV rays, while NMN addresses residual damage. After all, the core goal in tackling UV-related skin issues is not to never tan, but to ensure every sun exposure does not leave hidden risks of accelerated aging.