NEW STUDY: SIRT1, the NAD-dependent longevity enzyme, is normally found in the cell's nucleus. Circulating SIRT1 modifies PCSK9 to promote LDL cholesterol uptake into the liver & reduce plaque in mice. Consistent with this, people with high levels of circulating SIRT1 have fewer deaths from cardiovascular causes...

Survival: Red = lowest levels of circulating SIRT1 in blood

Here's the paper