Eating vitamin C rich foods each day may support thicker, firmer skin from within, according to a study from the University of Otago. The research, published in the Journal of Investigative Dermatology, found that dietary vitamin C is absorbed from the bloodstream into the skin, where it is linked to collagen production and measurable increases in skin thickness. In a release published by EurekAlert! on December 3, 2025, lead author Professor Margreet Vissers said, "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."
What the study measured
The trial followed 24 healthy adults in New Zealand and Germany who ate two SunGold kiwifruit a day for eight weeks. That provided a steady dose of about 250 milligrams of vitamin C daily. Using ultrasound and skin sampling, the team tracked how the nutrient moved through the body and what happened once it reached the skin.
Vitamin C levels in the participants’ skin closely matched the rising levels in their blood plasma. Professor Vissers said this correlation was stronger than the researchers had seen in any other organ they had studied, which suggests the skin pulls the vitamin from circulation efficiently. Participants showed a significant increase in skin thickness, a marker of collagen in the supportive dermal layer, along with renewal of the outer epidermal cells.
Why creams cannot reach as deep
Vitamin C is water soluble, so topical serums struggle to carry meaningful concentrations past the skin’s outer barrier. The EurekAlert! release noted that this limited absorption is one reason vitamin C has been added to so many skin cream formulas, even though the outer barrier blocks much of it.
Vitamin C from food or supplements does not face that barrier. Once it is in the bloodstream, it reaches living skin cells across all layers and is used in the building and repair of structural collagen. The body cannot make collagen without it.
How much vitamin C, and where it comes from
The researchers point to about 250 milligrams a day. The body does not store vitamin C, so levels can drop within a day without adequate intake. That daily amount can come from a mix of foods: citrus fruits, kiwifruit, strawberries, bell peppers, broccoli and leafy greens. The study used kiwifruit for its consistent vitamin C content, but the researchers say the benefit is not specific to that fruit. A varied diet with at least one high vitamin C source each day should give similar results. For people who do not reach 250 milligrams through food, the researchers say a quality supplement can raise plasma and, in turn, skin levels.
What this adds to skin science
The findings connect skin health to overall nutrition rather than to topical products alone. Vitamin C is a required cofactor for collagen synthesis, the protein behind skin strength and elasticity, so consistent intake matters for long-term structure. The same nutrient that prevents scurvy, a disease marked by severe collagen breakdown, is now being tied to the slower collagen losses of chronological aging. The study describes a shift from reactive anti-aging topicals toward daily dietary intake as a form of maintenance.
What to do now
- Put at least one high vitamin C food on your plate every day, such as kiwifruit, citrus, strawberries, bell peppers, broccoli or dark leafy greens.
- Keep vitamin C intake consistent each day, since the body does not store it and levels can drop within a day without adequate intake.
- Aim for roughly 250 milligrams a day from a combination of foods rather than a single source, the amount the researchers point to.
- If food alone does not get you there, consider speaking with a healthcare provider about your vitamin C intake.
- Treat topical vitamin C as surface antioxidant care, and rely on what you eat for collagen support in the deeper layers.
FAQ
Can vitamin C eaten in food really improve skin thickness?
In the University of Otago study, participants who ate two SunGold kiwifruit daily for eight weeks showed measurable increases in skin thickness and epidermal renewal, with vitamin C levels in the skin closely tracking rising levels in the blood. The researchers describe this as an association, not a cure.
How much vitamin C should I eat each day for skin benefits?
The researchers point to about 250 milligrams a day. Because the body does not store vitamin C, intake needs to be consistent. That amount can come from citrus fruits, kiwifruit, strawberries, bell peppers, broccoli and leafy greens, or a supplement when diet falls short.
Why are vitamin C creams not enough on their own?
Vitamin C is water soluble and poorly absorbed through the skin’s outer barrier, so serums deliver limited amounts to where collagen is built. Vitamin C taken through food or supplements enters the bloodstream and reaches all layers of the skin, where it is used in collagen production.
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