As we age, our skin naturally becomes thinner and more fragile due to a decline in cell production. The researchers found that vitamin C works throughout our life to counteract this aging process.

Using a 3D human skin model, they showed that C boosts thickness in the epidermal skin layer by activating genes linked to cell growth through DNA demethylation. These findings suggest that vitamin C may help prevent age-related skin thinning and support healthier, stronger skin in aging individuals.

The epidermis is the outermost layer of skin, and also the most susceptible to thinning during aging. As our first line of defense against pathogens, this loss of protective strength is problematic.

About 90% of the cells in the epidermis are keratinocytes, which originate from deeper layers of the epidermis and migrate upward, ultimately forming the skin's protective barrier. To combat aging's impact on skin, numerous studies have emphasized the benefits of vitamin C, a vitamin well known for its role in skin health and antioxidant properties.

Research led by Dr. Akihito Ishigami, Vice President of the Division of Biology and Medical Sciences at Tokyo Metropolitan Institute for Geriatrics and Gerontology, has found that vitamin C helps thicken the skin by directly activating genes that control skin cell growth and development.

"C seems to influence the structure and function of epidermis, especially by controlling the growth of epidermal cells. In this study, we investigated whether it promotes cell proliferation and differentiation via epigenetic changes," explains Dr. Ishigami, according to a release from his university.

To investigate how vitamin C affects skin regeneration, the team used human epidermal equivalents, which are laboratory-grown models that closely mimic real human skin. In this model, skin cells are exposed to air on the surface while being nourished from underneath by a liquid nutrient medium, replicating the way human skin receives nutrients from underlying blood vessels while remaining exposed to the external environment.

The liquid medium contained concentrations of C comparable to those typically transported from the bloodstream into the epidermis. On assessing its effect, they found that vitamin C influenced a thicker epidermal cell layer without significantly affecting the stratum corneum (the outer layer composed of dead cells) on day seven.

By day 14, the inner layer was even thicker, and the outer layer was found to be thinner, suggesting that vitamin C promotes the formation and division of keratinocytes. Treated samples showed increased cell proliferation, demonstrated by a higher number of Ki-67-positive cells—a protein marker present in the nucleus of actively dividing cells.