After the green kiwi was the first fruit to receive a health claim in EU, the sungold kiwifruit has recently been associated with a health effect, specifically on the skin. Indeed, by directly measuring vitamin C in human skin, researchers have demonstrated that diet can increase the skin’s vitamin C content and influence its structure, while also revealing the limits of its effects on collagen formation and UV protection.
In this new study published in the Journal of Investigative Dermatology, researchers directly examine how different skin compartments react to dietary ascorbate and whether these changes translate into measurable improvements in skin function. The researchers also conducted a pilot dietary intervention based on kiwifruit, providing approximately 250 mg/day of vitamin C, to test whether increasing plasma ascorbate levels raises the skin’s ascorbate content and alters skin function.
Through measurements of DNA content at the cellular level, researchers found that:
- The epidermis contained 11 times more DNA than the dermis, allowing for the estimation of cellular concentrations.
- Dermal fibroblasts contained approximately 6.4 mM of ascorbate, while epidermal keratinocytes contained approximately 0.9 mM, a difference of sevenfold.
- The high concentrations of dermal ascorbate are similar to those observed in adrenal and brain tissues, where ascorbate acts as an enzymatic cofactor, likely promoting significant collagen synthesis in fibroblasts.
- Ascorbate concentrations in whole skin, the dermis, and the epidermis increased proportionally to blood ascorbate levels. In the kiwi supplementation group, participants with lower than average baseline concentrations reached plasma saturation (> 60 μM), accompanied by an increase in dermal ascorbate in biopsies.
The researchers performed a second analysis using aspiration samples of blisters. They observed that the increase in plasma ascorbate was reflected in the blister fluid and in the epidermal tissue of the blister roofs, confirming active epidermal absorption via sodium-dependent vitamin C transporter (SVCT). Kiwi supplementation increased skin density by approximately 0.15 to 0.23 scan units, indicating a higher content of dermal structural proteins.
Epidermal cell proliferation also increased. However, skin elasticity decreased slightly (approximately 7%), and protection against UVA-induced oxidative stress was not improved. Type I procollagen peptides in the ampoule fluid did not increase, suggesting that changes in collagen synthesis may be subtle or undetectable by this biomarker, despite the increase in skin density.
The results suggest that dietary vitamin C effectively increases ascorbate levels in all skin compartments through active transport mechanisms. The improvement in skin density and epidermal turnover could reflect increased collagen support or TET-mediated transcriptional regulation, as observed in previous in vitro studies. The authors conclude: “Increased dietary ascorbate intake will allow for efficient absorption in all skin compartments and will improve skin function.”
For more information, you can consult the study article at this link.
Orchidali can support you for preparing and writting regulatory dossiers according to your needs and the authorities requirements.
Français
Sungold kiwifruit intake boosts vitamin C in skin and supports dermal structure
After the green kiwi was the first fruit to receive a health claim in EU, the sungold kiwifruit has recently been associated with a health effect, specifically on the skin. Indeed, by directly measuring vitamin C in human skin, researchers have demonstrated that diet can increase the skin’s vitamin C content and influence its structure, while also revealing the limits of its effects on collagen formation and UV protection.
In this new study published in the Journal of Investigative Dermatology, researchers directly examine how different skin compartments react to dietary ascorbate and whether these changes translate into measurable improvements in skin function. The researchers also conducted a pilot dietary intervention based on kiwifruit, providing approximately 250 mg/day of vitamin C, to test whether increasing plasma ascorbate levels raises the skin’s ascorbate content and alters skin function.
Through measurements of DNA content at the cellular level, researchers found that:
The researchers performed a second analysis using aspiration samples of blisters. They observed that the increase in plasma ascorbate was reflected in the blister fluid and in the epidermal tissue of the blister roofs, confirming active epidermal absorption via sodium-dependent vitamin C transporter (SVCT). Kiwi supplementation increased skin density by approximately 0.15 to 0.23 scan units, indicating a higher content of dermal structural proteins.
Epidermal cell proliferation also increased. However, skin elasticity decreased slightly (approximately 7%), and protection against UVA-induced oxidative stress was not improved. Type I procollagen peptides in the ampoule fluid did not increase, suggesting that changes in collagen synthesis may be subtle or undetectable by this biomarker, despite the increase in skin density.
The results suggest that dietary vitamin C effectively increases ascorbate levels in all skin compartments through active transport mechanisms. The improvement in skin density and epidermal turnover could reflect increased collagen support or TET-mediated transcriptional regulation, as observed in previous in vitro studies. The authors conclude: “Increased dietary ascorbate intake will allow for efficient absorption in all skin compartments and will improve skin function.”
For more information, you can consult the study article at this link.
Orchidali can support you for preparing and writting regulatory dossiers according to your needs and the authorities requirements.