Sirtuin 1 (SIRT1) is a gene that is expressed next to the promoter region of the ACE2 gene. Increased expression or activation of SIRT1 is positively associated with ACE2 expression. Factors that increase SIRT1 expression or activation include:

• calorie restriction
• resveratrol
• Vitamin C
• aspirin
• metformin
• vitamin B3

This may explain why a large Vitamin C dose can possibly have a rescuing effect for COVID-19 patients with severe acute respiratory distress syndrome.