Vitamin C: Good for the skin, especially if you eat it

Oranges – Flowers and fruit simultaneously. Image by By Ellen Levy Finch (Elf) – Own work, CC BY-SA 3.0.

Vitamin C is a popular addition to many skin products, designed to promote a healthier skin. New research indicates that vitamin C does not only belong in skincare products—it works even better when you eat it.

Scientists (University of Otago, Faculty of Medicine — Christchurch Ōtautahi) have discovered that vitamin C from food travels through the bloodstream into every layer of the skin, boosting collagen and skin renewal. In a study, people who ate two vitamin C–packed kiwifruit daily showed thicker, healthier skin. The findings suggest glowing skin really does start from within.

Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits, berries and vegetables. Vitamin C is an essential nutrient involved in the repair of tissue, the formation of collagen, and the enzymatic production of certain neurotransmitters.

In particular, the research found that vitamin C levels in the skin closely mirror levels in the blood (the protein-rich plasma component).

Maintaining steady vitamin C levels in the blood is essential, since the body does not store the vitamin long term.

Research process

The study followed 24 healthy adults in Aotearoa New Zealand and Germany. Participants who raised their plasma vitamin C levels by eating two vitamin C rich SunGoldTM kiwifruit each day showed a clear increase in vitamin C within their skin. This increase was associated with thicker skin (collagen production) and greater renewal of the outer skin layer.

Participants were asked to eat two Kiwi Gold kiwifruit daily for eight weeks. This provided the equivalent of 250 micrograms of vitamin C. The researchers then collected skin samples before and after the intervention, with separate analyses allowing them to look at the skin basal layers and the outer dermal skin layer and skin function.

The researchers also evaluated skin regeneration using ultrasound measurements of skin thickness, elasticity ultraviolet light protection and epidermal cell renewal to assess overall skin function.

The strength of the association between skin thickness and vitamin C intake was found to be “compelling”.

The relationship between blood vitamin C and skin vitamin C stood out compared to other organs, especially 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.

The research team also found that vitamin C circulating in the bloodstream reaches every layer of the skin and supports healthier skin function. In essence, vitamin C in the blood circulation penetrates all layers of the skin and is associated with improved skin function.

Results: Significant increase in the participants’ skin thickness levels

One of the most significant findings was a measurable rise in skin thickness among participants, indicating increased collagen production along with faster regeneration of epidermal cells.

Diet beats skin lotions

The researchers say their findings reinforce the idea that skin health begins internally, with nutrients delivered naturally through the bloodstream.

Vitamin C is essential for collagen production, which is why it is commonly added to skincare products. However, vitamin C dissolves easily in water and does not absorb well through the outer skin barrier. The study showed that skin cells are highly efficient at absorbing vitamin C from the blood, with uptake into the outer epidermal layer appearing to be a priority.

The research appears in the Journal of Investigative Dermatology, in a paper titled “Improved Human Skin Vitamin C Levels and Skin Function after Dietary Intake of Kiwifruit: A High-Vitamin-C Food.”