Are you asking if you can tell if your body has digested and absorbed a food by the color of your urine? The answer is no. Too many factors involved.
But, and maybe this is closer to what you are asking, if you are urinating clear fluid, it means you are hydrated. If you are urinating red liquid, it means the body has absorbed the beets and is eliminating whatever part of them it doesn’t require. All the individual molecules of the beets might not yet be allocated to cells permanently yet, but it does mean at least part of it is in your body and no longer only in your digestive tract.
>For example, beet. It gives a reddish color to the urine…
If urine gets reddish after consuming beetroots - it is a reason for reflecting about health. Such a medical condition has even its own name - beeturia.
If your urine is dark yellow or orange, you’re not getting enough water. If it’s light yellow to clear, you are. If it’s pink, red, very dark brown, black or cloudy, go see a doctor, but it may be benign.
If it’s blue, stop eating food with so much blue dye.
This is what you can learn from the color of your urine.