Scientists have measured for the first time how dietary vitamin C affects the level of ascorbic acid directly in human skin, and found that regular consumption of the vitamin-C-rich fruit — kiwi — truly raises these levels and influences the skin’s structure. The results were published in the Journal of Investigative Dermatology.
Healthy adults took part in the study. The researchers compared vitamin C concentrations in the blood with its content in the layers of the skin — the dermis and epidermis. They found that after a regimen in which volunteers ate SunGold kiwis daily (providing about 250 mg of vitamin C per day), the ascorbate level in the skin increased and approached the level seen in blood plasma.
Moreover, dermal cells — including the fibrous connective cells responsible for collagen — had noticeably higher vitamin C stores than the cells of the outer skin layer. This is important because vitamin C is a key cofactor in collagen synthesis, the protein responsible for the skin’s density, elasticity, and strength.
After eight weeks of kiwi consumption, participants showed a noticeable increase in skin density and faster renewal of epidermal cells — meaning the skin’s structure became denser and its “renewal” more active.
However, some parameters — such as resistance to ultraviolet radiation and the amount of biomarkers of new collagen — did not change significantly, and skin elasticity decreased slightly.
The authors emphasize that it is important not just to smear the skin with creams, but to maintain adequate vitamin C levels systemically through diet. Since the body cannot store vitamin C for long, a regular diet with foods rich in this nutrient — like kiwi, citrus fruits, berries, peppers, and broccoli — is beneficial.
The conclusion of the study: with a balanced diet, vitamin C effectively accumulates in the skin, improving its density and speeding up renewal — giving real benefits not only for appearance but also for skin health.
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