The key is balance. If you go too alkaline your body will throw just as much a hissy fit as if you went too acid. The body does however have some amazing balance mechanisms in it.
If you're too acidic having Citric Acid i.e. citrus fruits will cause your body to use calcium to bring the alkalinity up, therefore giving your body balance.
Conversely, if you're too alkaline, having anything with calcium in it will release Citric Acid to bring the acidity up and therefore providing the balance.
This is why recommending an alkali diet over an acid one or an acid diet over an alkali one is poorly thought out. We need a balanced diet, including meat, because it's the only way we can get the minerals our body needs.