Using toothpaste that contains both baking soda and hydrogen peroxide may help slow down teeth whitening. A 2012 study found that using toothpaste with hydrogen peroxide and baking soda improves tooth brightness and reduces tooth discoloration. A 2007 study found that vitamin C deficiency may exacerbate periodontitis, a disorder characterized by bacterial buildup on the gums and teeth. This aggregation leads to discoloration. The maintenance of a healthy vitamin C intake may therefore aid in the prevention of tooth discoloration. Further research is necessary to determine whether vitamin C administration can whiten teeth. Fruit enzymes can be added to toothpaste to prevent discoloration. A 2012 study found that toothpaste containing the pineapple and papaya enzymes papain and bromelain can help remove stains from teeth. When used moderately, apple cider vinegar may reduce tooth stains and improve whiteness. A 2014 study found that using apple cider vinegar can whiten teeth. But keep in mind that this was an animal experiment. Apple cider vinegar can damage the surface of teeth if used too frequently. The use of apple cider vinegar as a tooth whitener deserves more study. In the meanwhile, it should be used carefully and sparingly. A 2015 study found that oil pulling or coconut oil swishing may be an effective way to reduce plaque buildup on teeth. Coconut oil pulling could reduce discoloration since plaque growth can lead to yellowing.