Study shows dietary vitamin C intake boosts skin levels and improves skin function

Vitamin C (ascorbate) ingestion directly affects skin function, a new study demonstrates.¹ While the topical application of vitamin C has been studied as a way to promote skin health, there has been only one study on skin ascorbate after supplementation, the new research notes, and none have examined skin ascorbate content in relation to disease states or skin functions.

“We know that vitamin C is required for collagen production,” explains lead author Professor Margreet Vissers in a December 3, 2025, news release from the University of Otago, New Zealand.² “This fact has inspired the addition of vitamin C to many skin cream formulations. However, vitamin C is highly water soluble and poorly absorbed through the outer skin barrier. Our study shows that the skin is extremely good at absorbing vitamin C from the blood circulation. Uptake into the outer epidermal skin layer also seems to be prioritized.”

Study design: measuring vitamin C in skin samples

The study, “Improved Human Skin Vitamin C Levels and Skin Function after Dietary Intake of Kiwifruit: A High-Vitamin-C Food,” was published in the Journal of Investigative Dermatology in October 2025.

In the first part of the study, a cross-sectional analysis examined the relationship between blood plasma levels and dermal ascorbate in samples from individuals undergoing elective surgery.

The second part of the research – a pilot human dietary intervention study – examined the effect of increasing ascorbate levels on skin functions. This part involved 24 participants in two locations (Christchurch, New Zealand and Hamburg, Germany) who were given two SunGold kiwifruit daily for eight weeks, which provided approximately 250 mg of vitamin C daily. Skin samples were collected and analyzed.

The research was funded by Zespri International Ltd, a University of Otago Research Grant, and institutional funds.

Study results: correlation of vitamin C and skin function

In the cross-sectional section, the levels of dermal ascorbate were found to closely reflect whole-skin levels: a “significant positive linear relationship” was seen between epidermal and plasma ascorbate.¹ Additionally, though the ascorbate levels varied, it was not related to factors such as age, sex, or exposure to sun.

“We were surprised by the tight correlation between plasma vitamin C levels and those in the skin – this was much more marked than in any other organ we have investigated,” explained Professor Vissers.

In the in vitro section of the study, an increase in plasma ascorbate was associated with an increase in skin density and epidermal cell proliferation. “In summary, we have demonstrated that increasing dietary vitamin C intake boosts human skin ascorbate levels, with active uptake into the epidermis, which is particularly responsive to plasma ascorbate availability,” the researchers concluded. “We suggest that increasing dietary ascorbate intake will result in effective uptake into all skin compartments and will benefit skin function.”

“We are the first to demonstrate that vitamin C in the blood circulation penetrates all layers of the skin and is associated with improved skin function,” Professor Vissers added.

Impact on vitamin C supplementation

Though kiwifruit was used in this study, chosen for its high vitamin C levels, other fresh fruits and vegetables high in vitamin C are expected to produce similar effects on skin health, the news release adds.

“We suggest that increasing your dietary vitamin C intake will result in effective vitamin C uptake into all compartments of the skin,” Professor Vissers stated. “The important thing is to keep your plasma levels optimal, which we know can be easily achieved in a healthy person with a vitamin C intake of around 250 mg per day. The body however does not store the vitamin, so we recommend 5+ a day, every day, with one of those five being a high vitamin C food, as a good habit to cultivate.”

References

1. Pullar, JM.; Bozonet, SM.; Segger, D.; von Seebach, A, et al. Improved Human Skin Vitamin C Levels and Skin Function after Dietary Intake of Kiwifruit: A High-Vitamin-C Food. Journal of Investigative Dermatology, 2025. DOI: 10.1016/j.jid.2025.10.587.
2. University of Otago. Vitamin C from food boosts collagen levels in skin – landmark study. December 3, 2025. (Accessed 2026-01-02).