Why does water color go red when you boil maizes or lentils? Is it bad?
This is probably due to anthocyanins present in the maize and lentils. Despite the possibly worrying sounding 'cyanin', anthocyanins are antioxidants and if anything, beneficial to one's diet. Anyway the amount of anthocyanins present in maize is far far less than in say red cabbage (see the table in the Wikipedia article), so I think you have nothing to worry about.