The cariostatic actions of phosphates is primarily, if not entirely, a local topical one. The presence of phosphates in the oral environment prevents the loss of phosphorus from the tooth enamel because of the common ion effect. Phosphates, along with calcium and fluoride ions, contribute to the remineralization of incipient demineralized areas of enamel. The phosphates seem to improve the structural nature of the enamel surface by making it harder and smoother. By virtue of their detergent properties, phosphates can probably interfere with the adherence of pellicle and plaque bacteria to the enamel surface.
Phosphates can also inhibit bacterial growth.
Fats seem to reduce the cariogenicity of different foods but it is not clear how or to what extent. Some possible explanations may be that the fat would form a protective barrier on the tooth surface or maybe just surround the carbohydrates, making them less available and making the removal from the oral cavity a little faster. Some fatty acids have an antimicrobial effect which could have an impact on plaque formation. Cheese may reduce the levels of cariogenic bacteria according to some studies. The high calcium and phosphorus content also seems to be a factor in the cariostatic mechanisms of cheese as well as the casein and cheese proteins.