This is correct. If you juice beets, be careful. Yes, it will make your urine red, which is just weird, but much worse, it can also make you violently ill if you do too much. Apparently this doesn't happen to everyone, but for a lot of people it does, including me. I've been told (after the fact) to never do more than half a beet - I did three one morning. I started feeling sick, and then projectile puked periodically over the course of an hour until there was nothing left in me. I was then just weak and sick (bed ridden) for about 8 hours. At first I felt like death, but slowly started feeling better over the 8 hours until was back to normal. Was an extremely unpleasant experience. I don't juice beets any more. If you want to try it, start with small amounts and build slowly. Quote from an article about beets causing illness:
“Unfortunately, some people cannot drink beet juice, as it can cause sickness, vomiting, giddiness, heartthrob, and general weakness. You need to get used to concentrated beet juice little by little, starting with one tablespoon per day.â€