If the pH of the saliva goes below 5.5, it begins to damage the tooth enamel.
The two most commonly advised ways to protect one's teeth are brushing and flossing. Yet, if the saliva becomes too acidic, it will erode our enamel the entire time we sleep.
Our culture unfortunately does not transmit important knowledge that is widely known among researchers to the general public.
The saliva pH is at its lowest point when we wake up in the morning. Testing it is easy. To do so, we spit on a piece of pH paper (without putting it in one's mouth, it might be toxic) upon waking up, before eating anything. If it's 5.5 or lower, one could increase it by consuming certain foods.
Testing urine pH can be valuable to figure out which foods increase your saliva pH, because foods that increase urine pH typically also increase saliva pH. While it's most valuable to test saliva pH in the morning, one could check how certain foods affect urine pH during the day. I found that milk is one food that reliably increases pH. Foods which have a reduced amount of minerals, such as greek yogurt or farmers cheese, do not help to increase the pH.