Healthy skin is often seen as the result of creams, serums and external treatments. But in an era when pharmacy shelves overflow with promises of firming and renewal, it is easy to forget a basic truth: The skin is a living organ that responds to what enters the body no less than to what is applied to it.
For years, vitamin C has been marketed mainly in glossy bottles and cosmetic campaigns as a cornerstone of skincare. Now, new scientific findings are shifting the spotlight from the bathroom cabinet to the dinner plate.
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Not everything sold as a skincare solution actually reaches the skin
(Photo: Shutterstock)
A study conducted by researchers at the University of Otago in New Zealand and published in the Journal of Investigative Dermatology found that vitamin C levels in the skin closely reflect levels in the bloodstream. The researchers also found that increasing consumption of vitamin C-rich foods led to parallel increases in vitamin C concentrations in both the blood and skin tissue.
In practical terms, the study demonstrated a direct link between dietary vitamin C intake and the skin’s ability to produce collagen and renew itself. Skin health, the researchers found, responds measurably to vitamin C consumed through food, not only to topical treatments applied to the surface.
From biology to the plate
To determine whether vitamin C from food actually affects the skin itself and not just in theory, the researchers used a step-by-step approach. First, they established the biological connection between vitamin C levels in the blood and in the skin. Only then did they examine how dietary changes influence skin structure and function.
In the first stage, skin samples were taken from healthy individuals undergoing elective surgeries and compared with vitamin C levels measured in blood plasma. The goal was to determine whether vitamin C circulating in the bloodstream is reflected in skin tissue. This step was critical. Without such a link, dietary vitamin C would have little relevance for skin health.
Once the connection was confirmed, the researchers moved to a dietary intervention study. They followed 24 healthy adults of various ages from New Zealand and Germany whose blood vitamin C levels were relatively low. Participants were instructed to consume two vitamin C-rich kiwis daily for eight weeks, providing about 250 milligrams of vitamin C per day, a dose higher than standard dietary recommendations.
Before and after the intervention, researchers measured vitamin C levels in the blood and conducted detailed skin analyses, including biopsies from different skin layers. This allowed them to assess not only whether vitamin C levels rose, but whether those increases translated into structural and functional changes in the skin.
Measurable improvements
The results were consistent. Higher vitamin C levels in the blood were accompanied by higher levels in the skin, along with a significant increase in skin density, an indicator of stronger dermal structure, and faster skin cell renewal.
The researchers also found that vitamin C delivered through the bloodstream reached all layers of the skin, not just the surface. For the first time, the study demonstrated directly that a vitamin C-rich diet does not merely support general health, but produces measurable improvements in skin structure and function.
Lead researcher Professor Margreet Vissers described the findings as “particularly striking.”
“We were surprised by the very strong correlation between vitamin C levels in plasma and levels in the skin,” she said, noting that the link was stronger than in any other organ the team had studied. She added that the increase in skin density reflected improvements in the skin’s supportive structure and faster renewal of epidermal cells.
What Israeli experts say
While the research was conducted in New Zealand and Germany, its implications are also relevant in Israel. To better understand how the findings translate into dietary recommendations, we spoke with Adi Bezalel, a clinical dietitian in the Jerusalem district.
“This study is significant because it proves that vitamin C from food is absorbed into the bloodstream and reaches its target in the skin,” Bezalel said. “In this case, participants consumed two kiwis a day, providing 250 milligrams of vitamin C. Official guidelines usually focus on preventing deficiency, around 75 to 90 milligrams, but here we are talking about an optimal intake that benefits skin health.”
She noted that the study’s design, conducted in two countries, helped ensure a more diverse population and that skin tests showed real improvements in density and cell turnover.
More than collagen
Vitamin C’s role goes beyond collagen production, Bezalel explained. While collagen is often described as the building block of skin, vitamin C is essential for making that structure functional.
“If collagen is the bricks, vitamin C is the cement that holds them together,” she said. “Without vitamin C, the body cannot effectively use collagen for skin elasticity and appearance.”
Vitamin C also serves as a powerful antioxidant, protecting the skin from daily damage caused by UV radiation, pollution, stress hormones, lack of sleep and smoking.
Why food works better than creams
Vitamin C is water-soluble and does not penetrate the skin barrier efficiently when applied topically. The study showed that skin cells are far more effective at absorbing vitamin C delivered through the bloodstream, with a clear biological preference for uptake in the outer epidermal layer.
Because vitamin C is sensitive to heat and light, Bezalel recommends consuming it in fresh, raw form whenever possible.
“Fresh fruits and vegetables are key,” she said. “Red and yellow bell peppers contain even more vitamin C than oranges. A single guava can provide 200 to 300 milligrams. Strawberries and citrus fruits are also good options, and green vegetables like broccoli, Brussels sprouts and kale contribute as well, though cooking reduces their vitamin C content.”
She also emphasized consistency. Because vitamin C is water-soluble and not stored in the body, excess amounts are excreted in urine.
“That means daily intake matters,” Bezalel said. “It is not enough to consume a lot one day. You need a steady supply.”
A simple takeaway
Ultimately, both the research and clinical interpretation point to the same conclusion: Not everything sold as a skincare solution actually reaches the skin. While topical vitamin C products may have a role, the study shows that diet is a proven, measurable way to deliver vitamin C to skin tissue and improve its structure.
In a world full of quick fixes and complex solutions, the findings highlight a simple truth. The skin does not operate in a vacuum. It reflects what we eat, our daily habits and the small choices we repeat day after day.
Before searching for answers in a jar, the research suggests, it may be worth looking first at what is on the plate.