Astragalus and Centella Oral Supplements Raised Collagen 13.2% in 12-Week Trial
Centella asiatica has become a fixture in modern skincare — prized for calming inflammation, supporting the skin barrier, and speeding wound recovery. But what happens when you swallow it instead of applying it? A research team in Taiwan ran the numbers, and the results suggest the two routes work differently enough to complement each other.
The Study Design
Scientists from Kaohsiung Medical University and Chia Nan University of Pharmacy and Science tested a standardized extract called ACS, combining saponins (naturally occurring plant compounds with soap-like properties) from both Astragalus membranaceus and Centella asiatica. They compared topical application, oral supplementation, and the two combined.
The trial enrolled 150 adults, with 30% between their 20s and 40s and 70% over 40, predominantly women. Participants were divided into six groups of 25, each assigned to a randomized, double-blind, placebo-controlled protocol. Neither participants nor researchers knew who received the active formula until analysis was complete.
Groups were:
- Topical cream (5% ACS) for 4 weeks
- Oral capsules (125mg ACS, twice daily) for 12 weeks
- Combination of both for 12 weeks
- Corresponding placebo groups for each
Topical vs. Oral: Different Timelines, Different Strengths
The cream moved fast. After just 4 weeks, the topical group showed elasticity +6.5% (placebo +1.2%), collagen +8.7% (placebo +6.8%), pore area -10.6% (placebo -0.9%), and hydration +7.6% (placebo +1.8%).
The oral group took longer, but at 12 weeks the collagen picture shifted. Collagen density climbed 13.2%, surface roughness dropped 18.5%, and melanin (skin pigmentation) decreased 6.3%. In raw terms, oral supplementation produced a larger collagen gain than topical use over its respective timeframe.
Collagen measurements were taken via ultrasound imaging of dermal density. A 13.2% change is difficult to contextualize in absolute terms, but it reached statistical significance against placebo in this study.
What Happens When You Combine Both
The combination group’s 12-week results stand out. Collagen +13.7%, hydration +12.9%, elasticity +9.0%, melanin -8.2%, pore reduction -28.5%, skin texture +19.8%, brightness +4.2%. Across nearly every metric, the combination outperformed either approach on its own.
The pore reduction figure is particularly striking at -28.5%. Oral supplementation alone did not show notable pore improvement, and the topical cream reached -10.6% over 4 weeks. The implication is that the two delivery routes are acting through distinct mechanisms, and their effects accumulate rather than overlap.
How Saponins Work From the Inside
Astragaloside from Astragalus and asiaticoside plus madecassoside from Centella are the primary saponins studied here. These compounds are thought to stimulate fibroblasts, the cells residing in the dermis that manufacture collagen, while also activating pathways that reduce oxidative stress.
When taken orally, saponins are absorbed in the gut and reach the dermis via the bloodstream. This is a fundamentally different delivery pathway than a topical cream, which acts at the skin surface and penetrates partially into the epidermis. The non-overlapping mechanisms are likely why combining the two produced additive rather than redundant effects.
If You Already Use a Centella Cream
The ACS extract in this study is not the same as the Centella extract in most commercial skincare. It is a purified saponin blend from two plants in a specific ratio. Assuming that your current Centella toner paired with any Astragalus capsule will replicate these numbers is a stretch.
That said, the underlying logic this trial tests is sound. Collagen synthesis happens deep in the dermis, a layer topicals have limited reach into. An oral route can theoretically target that layer more directly. This study provides evidence for that mechanism working in practice, even if the exact formulation is not widely available yet.
Limitations Worth Noting
With 25 participants per arm, this is a small trial. The population skewed heavily toward women over 40, which limits how confidently results extend to younger age groups or men. And as with most industry-adjacent ingredient studies, independent replication with a different research team would strengthen confidence in the findings.
The specific ACS extract used is also a proprietary blend. Whether commercially available Astragalus and Centella saponin ingredients match the study formula is something to verify before treating this as a direct product recommendation.
FAQ
Can an Astragalus and Centella supplement actually increase collagen? In this trial, participants taking 125mg capsules twice daily for 12 weeks saw collagen density rise by 13.2%. A topical cream showed +8.7% in just 4 weeks, but the oral route produced a larger overall gain over the full study period.
If I already use a Centella cream, do I need to add an oral supplement? The combination group in this trial achieved collagen +13.7%, pore reduction -28.5%, and hydration +12.9%, outperforming either approach alone. Keep in mind this reflects a specific purified saponin blend, so results may differ from pairing a standard Centella cream with a generic supplement.
What are saponins and how do they affect skin? Saponins are naturally occurring plant compounds that foam like soap and serve a protective function in plants. In the body they are thought to stimulate fibroblasts (the cells that produce collagen), reduce oxidative stress, and support anti-inflammatory pathways. Astragaloside from Astragalus and asiaticoside from Centella are among the most studied.