A new human study suggests that getting enough vitamin C from whole foods may play a larger role in skin health than previously understood. Researchers at the University of Otago report that skin vitamin C levels rise in direct response to how much vitamin C people eat, and those increases may support collagen production and skin renewal.
The study, published in the Journal of Investigative Dermatology, tracked two dozen healthy adults in New Zealand and Germany. Participants were asked to eat two vitamin C–rich SunGold kiwifruit a day for eight weeks, providing about 250 milligrams of vitamin C. Blood and skin samples were collected before and after the intervention.
According to lead author Professor Margreet Vissers, the close link between vitamin C in the bloodstream and vitamin C levels in the skin was stronger than expected.
“We were surprised by the tight correlation between plasma vitamin C levels and those in the skin,” she said. The team also found that vitamin C reached all layers of the skin. As Vissers explained, “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.”
Participants in Germany also underwent ultrasound and laboratory assessments to measure skin thickness, elasticity and the renewal of epidermal cells. The researchers reported increases in skin vitamin C levels along with measurable changes in thickness and markers associated with regeneration. Vissers said the findings point to a simple idea: vitamin C from food may help the skin do its job more effectively.
“We know that vitamin C is required for collagen production,” she said, noting that topical vitamin C can be difficult for the skin to absorb.
The study’s results show that dietary vitamin C is readily taken up through the bloodstream, especially into the outer layer of the skin.
Although the study used SunGold kiwifruit because of its high vitamin C content, the authors note that many fruits and vegetables can provide similar amounts. Citrus fruits, berries, bell peppers and broccoli are all rich sources. For most healthy adults, the researchers suggest aiming for about 250 milligrams of vitamin C per day from food, spread across multiple servings, since the body does not store the vitamin.
While the study was small and involved healthy volunteers, the findings contribute to a growing body of research on how nutrition influences skin structure and function. For people looking to support collagen formation or skin renewal through their diet, adding a high vitamin C food to the daily rotation is a practical starting point.
This study was supported by Zespri International Ltd, a University of Otago Research Grant, institutional funds and the Cancer Society Canterbury West Coast Division, which provided support for the He Taonga Tapu Cancer Society Tissue Bank.