I'm a rarety in offices, I always take time out to have lunch away from my desk (30 mins) and if I want to eat some fruit I'll go on a 5 min break to sit away from my desk and look in the distance.
Other people will just sit in front of the computer solidly eating their noisey apples and smelly tuna salad at their desk.
Its a no brainer that breaks from the screen makes people more productive right?