The egg and grapefruit diet doesn't involve you only eating eggs and grapefruits for days on end. While that might cause you to lose weight and fast, it is not a healthy way of doing it and it doesn't include all the nutrients your body needs daily.
Yogurt contains lactobacillus, a good bacteria that helps fight bad bacteria in your intestines and vagina and helps your vagina stay in the optimal pH range. Eating yogurt regularly can prevent your vagina from becoming too basic, but it can also be used topically to cure a yeast infection or BV.
It can be administered to pools, spas, and garden ponds to raise the total alkalinity, this will also raise the pH level and make maintaining proper pH easier. In the event that the pH is low and the alkalinity is adequate or high, Baking Soda (sodium bicarbonate) should not be used to adjust the pH.