In recent paper published in Aging Cell, Dr. Sharpless out of the UNC Medical School reported that expression of protein p16INK4a appeared to increase exponentially with chronological age. Expression was measured in human blood and was found highest in peripheral blood T-lymphocytes (PBTL).
The discovery is exciting as it creates a relatively easy way to measure molecular age as opposed to chronological age. Data was taken from 170 blood donors and analysis showed that a higher expression of p16INK4a correlated to patients who smoked and had a low level of physical exercise, but did not correlate to gender or BMI.
The lack of correlation of p16INK4a with BMI might tempt one to conclude the effects of calorie restriction in humans to be minimal, but it is important to remember that calorie restriction is theorized to act as a famine response mechanism, and also that caloric intake does not necessary correlate with BMI. What would be truly interesting is to measure expression of p16INK4a in individuals who have been on a calorie restricted diet.
Liu, Y., Sanoff, H., Cho, H., Burd, C., Torrice, C., Ibrahim, J., Thomas, N., & Sharpless, N. (2009). Expression of p16INK4a in peripheral blood T-cells is a biomarker of human aging
Aging Cell DOI: 10.1111/j.1474-9726.2009.00489.x
