The only potential issue is that you would be reingesting some of these vitamins. The excessive amounts of water-soluble vitamins that supplements may put into your body are excreted in urine. Of course it depends what amount you use for amaroli - If it's only a spoonful it won't make much of a difference. If it's more like 200-250 ml, that could be significant. Some vitamins have safe maximum daily limits and you need to mind those.