Can two kiwis a day thicken skin and speed renewal, as this study shows?

A new study finds daily vitamin C-rich kiwifruit raised skin vitamin C levels, increased collagen-linked skin thickness, and sped up epidermal cell renewal over eight weeks

Eating more vitamin C can directly thicken the skin and speed up skin renewal, a new study has found.

 

The research, titled Improved Human Skin Vitamin C Levels and Skin Function after Dietary Intake of Kiwifruit: A High-Vitamin-C Food, published in the Journal of Investigative Dermatology, shows that vitamin C from food enters the skin, boosts collagen-linked skin thickness and improves cell regeneration.

 

Researchers found that increasing dietary vitamin C directly raised vitamin C levels in the skin, boosted skin thickness linked to collagen production, and accelerated skin cell renewal. In simple terms, eating vitamin C-rich foods did not just improve blood levels; it changed how the skin functions.

How was the study conducted? 

The research examined how vitamin C from food moves into human skin and whether it improves skin structure and performance. Scientists tracked both blood vitamin C (plasma) and vitamin C inside different layers of the skin. They then studied what happened after participants ate high-vitamin C kiwifruit every day for eight weeks.

 

What made this study different is that it directly measured vitamin C inside the skin itself rather than relying only on dietary surveys or blood tests.

 

The investigation had two parts. First, researchers analysed skin and blood samples from 38 healthy individuals undergoing elective surgery. This helped establish how closely blood vitamin C levels match vitamin C inside the skin.

 

In the second phase, 24 healthy adults in New Zealand and Germany consumed two SunGold kiwifruit daily for eight weeks, delivering about 250 mg of vitamin C every day. Skin biopsies, suction blister samples and advanced imaging were used to measure skin density, cell renewal and vitamin C penetration before and after the diet change. 

Does eating vitamin C increase vitamin C inside the skin? 

The researchers found a tight, direct correlation between plasma vitamin C and vitamin C levels in every layer of the skin. When blood levels rose after daily kiwifruit intake, vitamin C inside the skin rose in step.

 

Importantly, the outer skin layer, which plays a key role in protection and renewal, showed particularly strong uptake from the bloodstream.

Did vitamin C improve collagen, skin thickness, and skin renewal? 

This is one of the study’s most important findings. After eight weeks of daily vitamin C intake, participants showed a significant increase in skin density, measured using high-resolution ultrasound. Increased density reflects stronger structural proteins such as collagen.

 

Researchers observed that skin density rose from 0.154 to 0.228 scanner units, a change that was statistically highly significant. This provides direct human evidence that dietary vitamin C supports collagen-linked skin thickness.

 

The study also showed that vitamin C improved skin cell regeneration. Researchers measured epidermal cell proliferation using a biological marker called Ki-67, which reflects how actively skin cells are renewing.

 

After daily vitamin C intake, epidermal cell renewal increased significantly, indicating faster skin regeneration and repair. 

Is eating vitamin C better than using vitamin C creams? 

The study shifts the spotlight away from topical creams. Vitamin C is water-soluble and struggles to penetrate the skin barrier efficiently when applied externally. In contrast, the skin showed strong uptake when vitamin C arrived via the bloodstream.

 

In other words, dietary vitamin C may nourish all layers of the skin more reliably than creams applied to the surface. 

How much vitamin C did participants consume daily? 

Participants consumed about 250 mg of vitamin C per day, mainly through two SunGold kiwifruit. This intake was enough to push plasma vitamin C into what scientists call “saturation” levels in most participants.

 

Crucially, the body does not store vitamin C for long, which means consistent daily intake matters more than occasional large doses. 

Do you need kiwifruit specifically for skin benefits? 

Not necessarily. Kiwifruit was used because it delivers reliably high vitamin C. However, researchers note that other vitamin C-rich foods such as oranges, lemons, berries, capsicums and broccoli are also likely to offer similar benefits if consumed regularly.

 

The study provides human evidence that what you eat can reshape how your skin behaves at a biological level.  For more health updates, follow #HealthWithBS 

This content is for informational purposes only and is not a substitute for professional medical advice.