vitamin G

noun3

1. •
   (informal) time spent in nature, in a garden or greenspace, as a health benefit

   • The briefest summary of our program is in its title: Vitamin G, where G stands for the green space around us. Notions of beneficial effects of nearby green space have persisted throughout history. — 2006
2. •
   (Ireland, humorous) Guinness stout

   • ...a pint of Guinness at the Cheltenham Festival costs a mind-boggling £7.50. That makes it one of the most expensive pints of "Vitamin G", as it's dubbed, in the world. — 2023
3. •
   (old-fashioned) vitamin B₂ or riboflavin.