A research study analyzed blood samples from nearly 45,000 individuals enrolled in the UK Biobank project. It has been shown that examining thousands of proteins in plasma provides a detailed picture of how the body, and more specifically, individual organs and age, function. This work has the potential to change how researchers measure biological age, estimate disease risk, and the way they develop new interventions to enable people to stay healthier for longer.
Natural aging encompasses the gradual decline of various organ functions, accompanied by weakness and the onset of diseases such as heart failure, kidney disease, and dementia. While there are some promising methods of inducing anti-aging effects in animals through certain interventions, such as dietary restrictions or medications, replicating them successfully in humans has not been easy. There are many reasons for these challenges, but one of the primary reasons is the lack of accurate methods to measure changes in organ failure attributable to aging on an individual basis.
To address this problem, the study presented “organ age” values for 11 major systems, including the brain, cardiovascular, kidney, and immune systems. The researchers used machine learning algorithms trained to assess the biological age of specific organs by analysing plasma proteins that are most likely produced by those organs. By comparing disruptions in these proteins against a person’s chronological age, the models could estimate how fast or slowly each organ was aging.
Both the immune system and brain were of particular importance. Brains that looked older had a higher chance of developing Alzheimer’s and a greater risk of short-term mortality, while younger-looking brains, in addition to a strong immune system, had better outcomes. Individuals with both a “young” brain and immune profile had about 50% mortality risk of average agers.
Lifestyle factors also played a role in aging. People who were physically active and took specific supplements, such as vitamin C or fish oil, appeared younger. Women on estrogen therapy, after early menopause, showed slower aging in their arteries and immune systems. This suggests that personalized medicine might help to mitigate age-related degeneration in specific organs.
Interestingly, although older organs clearly increased health risks, the presence of multiple very young organs (excluding the brain and immune system) did not correlate with longer lifespan. The researchers noted that this finding was consistent with previous studies, which have shown that both high and low extremes can be hazardous. Most importantly, this tool is not meant to replace disease-focused clinical evaluations. Instead, it offers an additional perspective that can help to identify populations who may benefit from early interventions. More research is needed to replicate these results across diverse populations and to gain a better understanding of how protein-based age testing compares across cohorts.
Overall, the findings showed that measuring organ age using plasma proteins provides a more accurate and actionable perspective on aging compared to general measures alone. This approach could help identify individuals at higher risk of age-related diseases and support the design of targeted interventions to slow the progression of organ-level aging.
References: Oh HSH, Le Guen Y, Rappoport N, et al. Plasma proteomics links brain and immune system aging with healthspan and longevity. Nat Med. 2025. doi:10.1038/s41591-025-03798-1
