For example, spirulina, cinnamon, or a natural supplement that could make a noticeable difference.
OJ isn't a health food, it's junk. Eat an orange if you must, or just drink water and pop a multivitamin if you're worried about that. But don't drink OJ. Certainly not every morning. Your gut and teeth will both be better off without it.
The supplements industry is mostly a sham. You don't need any fancy chemicals to function well. Just eat enough, but not too much, of a relatively balanced diet. Supplement it with a cheap multivitamin if you're worried. That's all you need. Get some exercise, minimize stress, and you'll be way healthier than any supplement addict.
8 hours of sleep is one of the easiest ways to improve your health. It’ll improve your mental health, and also regulates hormones around cardiovascular health and weight.
As others have said, the sugar without fiber is probably net bad for you and most of the things that benefit your life probably aren't dietary.
There is no greater thing you can do for your physical health and especially your mental health than be below 20% bodyfat, that becomes asymptotically true if you are obese.
If you lift then some form of protein, or potentially creatine.
> one ingredient to add to it
Reflection.
Journal about your previous day/make a plan for the day ahead.
You might say, a time lock on the fridge, though only cheese fits that solution.
There is no other 'one ingredient' for better health. Your body needs a multitude of ingredients for 'better health' (whatever that means to you).