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Beeturia is passing of red or pink urine after eating beetroots or foods colored with beetroot extract or beetroot pigments. The color is caused by the excretion of betalain (betacyanin) pigments such as betanin. The coloring is highly variable between individuals and between different occasions and can vary in intensity from invisible to strong. The pigment is sensitive to oxidative degradation under strongly acidic conditions. Therefore, the urine coloring depends on stomach acidity and dwell time as well as the presence of protecting substances such as oxalic acid. Beeturia is often associated with red or pink feces.
The red color seen in beeturia is caused by the presence of unmetabolized betalain pigments such as betanin in beetroot passed through the body. The pigments are absorbed in the colon. Betalains are oxidation sensitive redox indicators that are decolorized by hydrochloric acid, ferric ions, and colonic bacteria preparations. The gut flora plays a not yet evaluated role in the breakdown of the pigment.
Several older studies were hampered by the high variability of the coloring and several older hypotheses have been disproven:
The extent of excreted pigment depends on: