Humans do not age gradually. The rate of aging appears to accelerate around the age of 50.
Guang-Hui Liu, a researcher at the Institute of Zoology at the Chinese Academy of Sciences, noted on the 26th in the international journal 'Cell' that "an analysis of the changes in proteins in human organs found that there is an inflection point around the age of 50, after which aging accelerates."
The researchers analyzed organ tissues from 76 individuals aged 14 to 68 who died from brain damage. They collected tissues from organs representing eight body systems, including the cardiovascular, immune, and digestive systems. As a result, it was found that the levels of 48 proteins associated with diseases increased with age.
In particular, the rate of aging differed among organs. For example, changes in protein levels in the adrenal glands began around the age of 30, indicating that aging occurs more rapidly in these glands. The adrenal glands, located above both kidneys, produce hormones. The researchers analyzed that as the protein levels in the adrenal glands changed, it disrupted hormone balance, thus influencing aging.
Michael Snyder, a professor at Stanford University School of Medicine, remarked in the international journal Nature on the same day that it is "consistent with the idea that hormone and metabolic regulation are critical issues," adding that "the most profound changes occur precisely in this area as we age."
Previously, a research team led by Professor Tony Wyss-Coray at Stanford University reported in 2023 that even within the same individuals, the rate of aging varies among organs. The findings from the Chinese researchers corroborated this.
The protein levels in the organs exhibited significant changes at around the ages of 44 to 55. The most dramatic change occurred in the aorta. The aorta is the blood vessel that supplies blood from the heart to various parts of the body. The levels of the GAS6 protein, associated with aging, increased in the aorta.
When the researchers administered this protein to mice, aging was accelerated. Professor Liu speculated that "blood vessels seem to act as a conduit carrying molecules that promote aging throughout the body." The researchers noted that "the age around 50 is the inflection point for aging," stating that "blood vessels have been found to be particularly vulnerable to aging."
Dr. Maja Olecka from the Leibniz Institute for Aging in Germany stated that "there are a series of changes associated with aging," but added, "it remains challenging to draw general conclusions about the timing of the inflection point." He expressed hope that as researchers increasingly incorporate detailed temporal changes rather than simply comparing young and old individuals, major molecular pathways related to aging will be revealed.
References
Cell(2025), DOI : https://doi.org/10.1016/j.cell.2025.06.047
Nature(2023), DOI: https://doi.org/10.1038/s41586-023-06802-1