Bioavailability of metal ions

A method for determining the effect of an oral care agent on the bioavailability of one or more zinc ions in a composition comprising a source of the zinc ions and bacterial cells, wherein the method comprises:

• a. incubating a sample of the composition comprising the source of the zinc ions and the bacterial cells with the oral care agent,
• b. determining the viability of the bacterial cells after the incubation by comparing the viability to the measurements obtained without the oral care agent,
• c. incorporating the oral care agent into a second sample of the composition comprising the source of the zinc ions and the bacterial cells,
• d. incubating the second sample of the composition comprising the source of the zinc ions and the bacterial cells with the oral care agent,
• e. determining the viability of the bacterial cells after the incubation, and
• f. comparing the viabilities as determined in steps b) and e);
• wherein the source of zinc ions comprises one or more zinc ion sources selected from the group consisting of:
• zinc chloride, zinc citrate, and zinc oxide;
• wherein the oral care agent is selected from the group consisting of surfactants, desensitizing agents, whitening agents, tartar control agents, binders, thickening agents, detergents, adhesion agents, foam modulators, pH modifying agents, mouth feel agents, sweeteners, flavorants, colorants, humectants, fluoride sources, dyes, fragrances, viscosity modifiers, buffering agents, antioxidants, chelating agents, opacifiers and combinations thereof;
• and
• wherein the bacterial cells are selected from the group consisting of:
• Actinomyces viscosus, Lactobacillus casei, Streptococcus oralis, Fusobacterium nucleatum, Veillonella parvula, Escherichia coli, Serratia marcescens, and a mixture thereof.