Beautiful skin does come from within… the skin of a certain superfood.
Researchers from the University of Otago in New Zealand have found a direct correlation between collagen production and the amount of vitamin C in our daily diets.
The study, published in the International Journal of Investigative Dermatology, found that vitamin C levels in skin cells are closely tied to those in plasma and can be elevated by increased fruit intake.
The study, which followed participants in New Zealand and Germany, found that consuming two kiwis per day increased vitamin C levels in skin, improving collagen production and stimulating skin renewal.
“We were surprised by 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,” Lead author, Professor Margreet Vissers said in a statement.
“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.”
Participants were told to eat two kiwis — the equivalent of 250 micrograms of vitamin C — every day for eight weeks. Skin samples were collected before and after.
Factors like skin thickness, elasticity, UV protection and epidermal cell renewal were measured.
“The findings showed a significant increase in the participants’ skin thickness levels, reflecting collagen production and an upsurge in the regeneration of their epidermal cells, in other words, skin renewal,” Vissers said.
She notes that while vitamin C has long been added to skin cream formulations, it is highly water-soluble and poorly absorbed through the outer skin barrier — suggesting that an inside-out, consumption versus application approach is best for maximizing the skin-boosting benefits.
“Our study shows that the skin is extremely good at absorbing vitamin C from the bloodstream. Uptake into the outer epidermal skin layer also seems to be prioritized,” she said.
While kiwis were used in this study due to their high vitamin C levels, study authors suspect other fruits and vegetables with similar levels — including citrus, berries, bell peppers and broccoli — would have a similarly positive effect on skin health.
“We suggest that increasing your dietary vitamin C intake will result in effective vitamin C uptake into all compartments of the skin,” Vissers said.
“The important thing is to keep your plasma levels optimal, which we know can be easily achieved in a healthy person with a vitamin C intake of around 250mg per day.”
Because the body can’t produce vitamin C on its own, getting enough through diet is crucial as the antioxidant helps neutralize free radicals that damage cells, giving the immune system serious support.
In addition to staving off colds and giving skin a glow up, studies have found that kiwis can boost bowel function and ease symptoms of irritable bowel syndrome. They also improve stool frequency and consistency, making them a natural ally against constipation.
And the green flags for the green fruit keep on coming.
Scientists found that eating kiwi can boost one’s mood in as little as four days.
Kiwis are also a known sleep aid. In a study of 24 adults, eating two kiwis an hour before bed led to “significantly” longer sleep, better sleep quality, and a quicker time dozing off.
Research also suggests kiwis can support heart health, protect against eye disease, and aid in weight management.
