1. An oral care composition comprising: a first metal salt having a solubility of more than 0.001 g / 100 ml in water at a temperature of 20 ° C； a second metal salt having a solubility of 0.001 g / 100 ml or less in water at a temperature of 20 ° C； and an unbound water content of more than about 10%, by weight, in which the first metal salt and the second metal salt are independently selected from zinc salt, divalent tin salt and copper salt； and wherein the second metal salt is present in an amount effective to provide a synergistic increase in the delivery of metal ions of the first or second metal salt. The composition of claim 1, wherein the first metal salt and the second metal salt are salts of the same metal. A composition according to claim 1 or 2, wherein the second metal salt is present in an amount effective to provide a synergistic increase in the delivery of metal ions of the first metal salt. The composition of claim 1, wherein the first metal salt is selected from zinc citrate trihydrate, zinc chloride, zinc lactate, zinc nitrate, zinc acetate, zinc gluconate, zinc glycinate and zinc sulfate. The composition of claim 1, wherein the second metal salt is selected from zinc oxide, zinc phosphate, zinc pyrophosphate, zinc silicate, zinc oleate, zinc hydroxide, zinc peroxide and zinc sulfide. The composition of claim 1, comprising: from about 0.1 to about 5%, by weight, of the first metal salt； iot from about 0.05 to about 2%, by weight, of the specified second metal salt. The composition of claim 1, comprising: from about 0.5 to about 4%, by weight, of the first metal salt； iot from about 0.1 to about 1.5%, by weight, of said second metal salt. The composition of claim 1, comprising: from about 1 to about 3%, by weight,1. Композиция для ухода за полостью рта, включающая:первую соль металла, имеющую растворимость более 0,001 г/100 мл в воде при температуре 20ºС；вторую соль металла, имеющую растворимость 0,001 г/100 мл или менее, в воде при температуре 20
