The relative absorption of a curcumin phytosome formulation ( CP ) , a formulation with volatile oils of turmeric rhizome ( CTR ) and a formulation of curcumin with a combination of hydrophilic carrier , cellulosic derivatives and natural antioxidants ( CHC ) in comparison to a standardized curcumin mixture ( CS ) was investigated in a randomized , double-blind , crossover human study in healthy volunteers .