Research Says This Vitamin Can Firm Skin & Boost Collagen From The Inside Out
Vitamin C is an ingredient I have recommended countless times in my tenure as a beauty editor, perhaps more so than any other ingredient out there. But it’s not just me! It’s perhaps one of the most celebrated skin care ingredients—from dermatologists and estheticians to editors and influencers.
Just a peek at past research reveals why: Vitamin C is a powerful antioxidant, which means it helps the skin deal with damaging free radicals and aging oxidative stress.
But there are a lot of antioxidants out there. So what makes vitamin C so special? Its role in the production of collagen, the protein responsible for skin’s firmness, strength, and structure. Vitamin C is an essential part of the collagen synthesis process—in fact, your body cannot produce collagen without it.
This means if you want to help your skin produce and protect collagen with age, vitamin C is a non-negotiable.
But new research reveals something remarkable: The vitamin may be more impactful when you consume it, rather than slather it on your face.
Study reveals dietary vitamin C may be the key to healthier skin
A new study published in the Journal of Investigative Dermatology shows a direct, measurable relationship between dietary vitamin C intake and healthier, thicker, firmer skin.
In the study, the researchers discovered that vitamin C from food travels through the bloodstream and into all layers of the skin, where it supports collagen production and skin renewal. Even more striking: vitamin C levels in the skin closely mirrored levels in the blood.
- Following 24 healthy adults, researchers asked participants to eat 2 vitamin-C rich kiwifruits each day.
- With daily consumption, for 8 weeks it showed a clear increase of vitamin C in the skin following the intervention.
- Using ultrasound technology and skin sampling, they found that the increase led to thicker skin (a sign of increased collagen production in the dermal layer) and improved skin renewal at the cellular level (indicated by an upsurge in the regeneration of epidermal cells).
“We were surprised by the tight correlation between plasma vitamin C levels and those in the skin,” lead author Margreet Vissers, PhD, a professor at the University of Otago, said in a statement. Compared to other organs previously studied, the skin showed a uniquely strong response to dietary vitamin C. “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.”
How much vitamin C-rich foods you need to eat too see results
Kiwifruit was chosen for the study because its vitamin C content is consistent and easy to measure. Researchers expect similar benefits from other vitamin C–rich foods, including citrus fruits, berries, bell peppers, broccoli, and leafy greens.
Aim for optimal levels of at least 250 mg of vitamin C per day.
The key takeaway is daily intake. Vitamin C isn’t stored long-term in the body, so blood levels rise and fall based on what you eat that day.
And for additional support, you can rely on vitamin C supplements, either as a standalone formula or within a more robust formulation. My favorite collagen supplement includes vitamin C alongside the amino acids, which makes collagen synthesis far more efficient. In addition, it also contains hyaluronic acid and vitamin E.
Dietary vitamin C vs. topical: Form matters
As noted, vitamin C is essential for collagen synthesis. But your body cannot make vitamin C on its own. It needs to be supplied.
While topical vitamin C can help protect the skin’s surface, it struggles to penetrate deeply due to the skin barrier.
Vitamin C delivered through the bloodstream faces no such limitation. This study suggests the skin prioritizes vitamin C delivered internally, absorbing it efficiently from circulation and distributing it where it’s needed most.
That doesn’t make topical vitamin C useless, but it reframes expectations. Think of skincare as support, and nutrition as foundation.
The takeaway
If firmer skin, stronger collagen, and better long-term skin function are on your 2026 priority list, your grocery cart matters just as much as your serum lineup. This research adds to the ever growing body of evidence that skin health is deeply connected to daily nutrition, and vitamin C sits at the center of that relationship.
Simple, affordable, and backed by science, this may be one of the most effective skin strategies to commit to this year.
