Researchers have found that increasing vitamin C intake through diet can raise its levels in human skin and affect certain aspects of skin structure, though the benefits appear to have limits regarding collagen formation and protection from ultraviolet (UV) damage.
The study, published in the Journal of Investigative Dermatology, directly measured vitamin C concentrations in both the dermis and epidermis—the two main layers of the skin—of healthy adults. Participants were given kiwifruit, which provides about 250 mg of vitamin C per day, to see if higher blood ascorbate levels would translate into changes within the skin itself.
Vitamin C is known for its antioxidant properties and its role in supporting collagen production. It helps neutralize free radicals generated by UV exposure and supports cellular processes important for maintaining skin thickness. While topical application of vitamin C faces challenges due to absorption barriers, dietary intake relies on specific transporters (SVCT1/SVCT2) that actively move ascorbate from circulation into skin cells.
In this research, scientists determined that dermal fibroblasts contained much higher concentrations of ascorbate than epidermal keratinocytes—about seven times more. This high concentration in the dermis is similar to levels seen in tissues like the adrenal glands and brain.
When participants with lower baseline plasma ascorbate consumed kiwifruit daily, their blood levels reached saturation. This increase was reflected by higher ascorbate concentrations in all sampled areas of their skin. Additional tests using suction-blister sampling confirmed active uptake of vitamin C into epidermal tissue via SVCT transporters.
Skin density—a marker for structural protein content—increased following supplementation with kiwifruit. There was also an uptick in epidermal cell proliferation. However, there were no improvements observed in UVA-induced oxidative stress protection or increases in biomarkers associated with new collagen synthesis; procollagen type I peptides did not rise despite greater overall skin density. Skin elasticity decreased slightly by about 7%.
According to the authors: “Increasing dietary ascorbate intake will result in effective uptake into all skin compartments and will benefit skin function.”
These findings suggest that while dietary vitamin C can enhance certain features related to dermal structure and cell renewal through active transport mechanisms, it may not significantly boost all aspects traditionally associated with improved collagen synthesis or UV protection.
