Tests revealed the older mice who received the young blood had higher concentrations of regulatory compounds such as tricarboxylic acid, evidence of chemical processes that are usually interrupted by aging, increased production of mitochondria 'powerhouses', reduced inflammation, and greater expression of genes associated with longer life.

"This effect correlates with a longer life span, improved physiological parameters and a globally rejuvenated" genetic regulatory and cell protein systems the team explain in their paper, confirming three month blood circulation link was far more effective than previously studied short-term blood sharing (five weeks).