It's just water.  Haven't you noticed it gets orangier and orangier as the games go on?  Magnus bites the inside of his cheeks while he ponders moves.   Whenever he takes a drink it makes the water in his bottle get bloodier.

his "OJ" is radioactive 

Orange juice mixed with water

sorry for the bump folks.  but this is important.

http://chess-news.ru/en/node/18690

Мagnus Carlsen: "I No Longer Drink Orange Juice"

ever since he has taken 4 years to regain his 2882 rating.

so if he had stick with the orange juice, his rating would have been better ?

serve him right for not listening to his dietitian.

Orange juice gives me terrible acid stomach.

Guys, it's egg yokes.

That's how winning is done!

Why will he even drink orange juice?

I guess Norwegian-styled orange

Or maybe it's Kasparov's blood after all