 Beet ( Beta vulgaris ) , a plant native to the Mediterranean Basin , was already grown in antiquity . Only the leaves were of culinary use , as the tapered , tough , whitish and bitter @-@ tasting root was considered unfit for human consumption . It is likely that beet greens were used in variants of green borscht long before the invention of the beetroot @-@ based red borscht . Beet varieties with round , red , sweet taproots , known as beetroots , were not reliably reported until the 12th century and did not spread to Eastern Europe before the 16th century . Mikołaj Rej , a Polish Renaissance poet and moralist , included the earliest known Polish recipe for pickled beetroots in his 1568 book , Life of an Honest Man . It would later evolve into ćwikła , or chrain mit burik , a beet @-@ and @-@ horseradish relish popular in Polish and Jewish cuisines . Rej also recommended the " very tasty brine " left over from beetroot pickling , which was an early version of beet sour . The sour found some applications in Polish folk medicine as a cure for hangover and – mixed with honey – as a sore throat remedy . 
