A 16-week randomized trial in Singapore found that soy and casein protein supplements alter specific plasma markers, while overall skin glycation remains unchanged.
In September 2026, a new study published in the journal Nutrients revealed how different protein supplements influence specific plasma markers in older adults. NutraIngredients reported on a 16-week, single-blinded, three-arm randomized controlled trial conducted in Singapore. The researchers monitored 65 adults aged 60 to 80 to see how specific protein sources affect advanced glycation end products.
Advanced glycation end products are compounds that form in the body, and scientists track them to understand metabolic changes over time. The core announcement is that different protein supplements produce distinct changes in certain plasma markers, while overall glycation levels in the skin and body remain completely unchanged. The report identifies the published paper by its digital object identifier, DOI 10.3390/nu18172925, adding a new layer to our understanding of nutrition and healthy aging.
During the 16-week trial, participants followed Singapore’s My Healthy Plate dietary pattern. The report describes this dietary pattern as including wholegrains, meat and other foods, alongside fruits and vegetables. To test the specific biological effects of supplemental proteins, participants were assigned to a control group or received an additional 20 grams per day of either soy protein isolate or casein protein isolate. The study protocol strictly required that these protein powders were taken with 250 milliliters of low-fat milk.
The trial report described a significant rise in a specific plasma marker called CML in the soy group. Meanwhile, the casein supplementation group showed an increase in a different marker known as pentosidine. These specific responses show that the biological processing of different proteins can yield varied effects on individual markers within the bloodstream.
However, the most reassuring overall result from the researchers was what did not change during the trial. The report says that total circulating advanced glycation end product levels, skin levels, and dietary levels were reported as unchanged. This means the 16-week protein supplementation did not alter the total compounds accumulated under the skin or circulating throughout the body.
Different protein sources simply produced different responses in specific, isolated markers. Readers interested in the broader context of metabolic health and skin aging often ask how these markers relate to visible changes, which makes these stable overall levels particularly noteworthy.
When evaluating clinical research, we always look for the complete statistical picture to fully understand the real-world impact. The available report identifies the journal article and its exact publication details, noting it was published in the journal Nutrients. However, the summary report does not provide numerical effect sizes, confidence intervals, or specific p-values for the reported CML result. It also lacks a detailed breakdown of results by each trial arm.
This limited statistical visibility means we cannot easily measure the absolute magnitude of the changes observed in the 65 participating adults. We know the trial observed these older adults over a full 16 weeks, and we know they consistently consumed 20 grams of protein daily with low-fat milk. Yet, without precise confidence intervals and effect sizes, it is difficult to determine how dramatically these markers shifted compared to baseline levels. This is why we always emphasize looking at the broader clinical outcomes rather than fixating on isolated statistical mentions.
The scientific uncertainty in this trial is highly visible and carefully noted by the researchers themselves. The researchers advised caution about interpreting the casein and pentosidine result, specifically noting that the time by group interaction was not statistically significant. This statistical detail suggests that the relationship between taking casein and the rise in pentosidine over time requires much more investigation before any definitive statements can be made.
To explain the results, the researchers proposed that soy’s unique amino acid composition could help explain the CML result. They also suggested that the slower digestion rate of casein might relate to the pentosidine result observed in that specific trial arm. Importantly, they stated directly that these proposed explanations remained speculative. This uncertainty exists because post-meal amino acid concentrations and the actual formation pathways of these advanced glycation end products were not directly measured during the study.
Furthermore, these findings are solely about specific plasma biomarkers over a relatively short 16-week intervention. The report does not show that either supplement changed visible skin aging, fracture risk, or any other measurable clinical outcomes that consumers usually care about. The unchanged total circulating and skin measures provide incredibly important context here. The reported differences in individual plasma markers should not be presented as evidence of an overall increase or decrease in glycation throughout the body.
When our team first started reviewing clinical trials on nutrition and healthy aging, I was struck by how often the media misinterpreted the data. A study showing a minor shift in a single lab marker would suddenly be headlined as a major health risk or a massive breakthrough. It made me realize how desperately consumers need a translator for beauty science, someone who can clearly say exactly what a study proves and what it does not prove.
At Younell, our core mission is to help readers separate useful evidence from marketing noise. We promote looking and feeling well over time instead of chasing short-term trends. When a new trial reveals a subtle biological shift, it is incredibly easy for consumers to feel sudden anxiety about their daily habits. However, we believe that clearly understanding the science behind these changes brings reassurance rather than fear.
For readers choosing daily protein supplements, this trial alone does not justify avoiding soy or casein entirely. It also does not mean you should constantly switch your preferred protein sources simply to try and alter skin aging. The trial reports biomarker findings rather than establishing a tested consumer strategy for long-term health. Since the total circulating advanced glycation end products and skin markers were completely unchanged, there is no need to overhaul your entire routine based on these isolated biological shifts.
Instead, this research supports the general value of consuming a wide variety of proteins as part of a healthy, balanced diet. It reinforces the core principles we outline in our comprehensive guide to protein for skin, hair, and healthy aging. We recommend focusing on meeting your daily nutritional needs through a balanced dietary pattern, rather than worrying about minor fluctuations in a single plasma marker.
The fact that overall skin glycation remained remarkably stable is a positive sign for those using standard protein supplements daily. If you are comparing different supplement options, you can read more about how collagen differs from complete protein to make the most informed choices for your body.
As researchers continue to map how isolated nutrients influence our internal chemistry, we have to wonder how long it will take for longer clinical trials to connect these subtle plasma shifts to visible, long-term changes in human skin and bone density.
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