Are you as old as you feel, as old as you look or as old as your birth certificate says? The best answer may be “none of the above.”
Actually, you may be as biologically old as your blood says you are.
For many years, aging researchers have sought markers of biological age, or biomarkers —simple signals that reveal the expected length of your future health. The expected length of future health, after all, is the key biological difference between younger and older people.
Some people have called such markers “biological clocks.” I don’t know about you, but I don’t typically calculate my age by thinking of clocks. I think of calendars. So, I prefer to call these hypothetical signals “biological calendars.”
Plasma proteins may turn out to be just the type of biological calendar we are seeking.
The importance of these calendars is that they potentially allow researchers to quickly see whether a new drug, diet or other treatment that purports to slow, or even possibly reverse, aging is actually doing so.
Biological calendars of aging can also provide rapid feedback on how a lifestyle change, such as in diet or exercise habits, is affecting your biological age. This insight can motivate people to stick with that change.
Researching Blood for Aging Clues
Now, as a biological calendar, blood is a devilishly complex stew. Like a stew, it is liquid with lumps in it. We call the liquid plasma; the lumps, cells. Physicians for the past century have been using chemical analysis of plasma and counts of the various blood cell types to diagnose diseases. But we are now entering a brave new world of blood analysis.
Plasma contains not just the dozen or two chemicals that standard laboratory tests measure; it contains a constantly changing mixture of vitamins, nutrients, waste products, hormones and thousands of different proteins.
A hint that plasma might hold secrets about aging has come from research in which the plasma from young mice (or humans!) was found to rejuvenate the function of muscles, brain, heart and other organs of old mice. Dracula, it turns out, may have been onto something.