Collagen Production and Skin Renewal Directly Respond to Amount of Vitamin C We Consume: Study

Vitamin C levels in the skin are closely linked to vitamin C levels in the blood (plasma) and can be increased by increasing fruit consumption, according to a new study. Conducted on two dozen healthy adults in New Zealand and Germany, the study shows that increasing plasma levels by consuming two vitamin C-rich kiwis per day increases the amount of the vitamin in the skin, improving skin thickness (collagen production) and stimulating the renewal and regeneration of the outer layer of the skin.

Vitamin C (ascorbate) is present in all compartments of the skin. To pull and others. conducted an extensive investigation to establish the relationship between plasma and skin ascorbate levels, with emphasis on major skin compartments. Image credit: Pullar and others., doi: 10.1016/j.jid.2025.10.587.

“The strength of the association between skin thickness and vitamin C intake is compelling,” said Professor Margreet Vissers of the University of Otago, lead author of the study.

“We were surprised by the close correlation between plasma vitamin C levels and those in the skin – this was much greater than in any other organ we studied. »

“We are the first to demonstrate that vitamin C in the bloodstream penetrates all layers of the skin and is associated with improved skin function. »

“I am very proud of my team and excited about what the data is telling us. »

The results suggest that beauty truly comes from within, supporting your skin’s functioning from the inside out by delivering vitamin C to the skin the way nature intended – via the bloodstream.

“We know that vitamin C is necessary for the production of collagen”

“This fact has inspired the addition of vitamin C to many skin cream formulations.”

“However, vitamin C is highly soluble in water and poorly absorbed through the external skin barrier.”

“Our study shows that the skin absorbs vitamin C from the bloodstream extremely well.”

“Absorption into the outer layer of the epidermis also appears to be a priority.”

In the study, the authors established the association between plasma and skin levels of vitamin C, using healthy skin tissues from patients undergoing elective surgical procedures.

They then participated in a before-and-after vitamin C dietary intervention study at two sites – in Christchurch, New Zealand and Germany – each with 12 healthy participants.

“Everyone was asked to eat two kiwis a day, the equivalent of 250 micrograms of vitamin C, for eight weeks,” Professor Vissers said.

“We then collected skin samples before and after the procedure, with separate analyzes allowing us to examine the basal layers of skin in Christchurch and the outer skin layer and skin function tests in Germany.”

The researchers also measured the regeneration of skin samples – including ultrasound-tested measurements of skin thickness, UV protection elasticity and epidermal cell turnover – giving a comprehensive picture of skin function.

“The other really substantial result showed a significant increase in the thickness of the participants’ skin, reflecting the production of collagen and an increase in the regeneration of their epidermal cells, in other words skin renewal,” Professor Vissers said.

Scientists suggest that increasing your dietary intake of vitamin C will result in effective absorption of vitamin C into all compartments of the skin.

“The important thing is to maintain your optimal plasma levels, which we know can be easily achieved in a healthy person with a vitamin C intake of around 250 mg per day,” Professor Vissers said.

“The body doesn’t store the vitamin though, so we recommend 5+ per day, every day, with one of those five being a vitamin C-rich food, as a good habit to cultivate.”

The study was published on October 28, 2025 in the Journal of Investigative Dermatology.

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Juliette M. Pullar and others. Improved human skin vitamin C levels and skin function after dietary intake of kiwi: a food rich in vitamin C. Journal of Investigative Dermatologypublished online October 28, 2025; doi: 10.1016/j.jid.2025.10.587