The only direct measurements of relativistic effects have been in the nanosecond range, e.g. http://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experime... - not a scale on which you could measure human ageing.

But it's really just utterly implausible that it would happen any differently, because biology is just (complex combinations of) ordinary physical processes that follow the ordinary laws of physics like any other. Compare e.g. http://lesswrong.com/lw/hq/universal_fire/