Final answer:
The alkaline ash diet increases urine pH levels making the urine more alkaline. This is due to the consumption of alkaline-producing foods, particularly from vegetarian diets, as opposed to acid-producing foods like animal proteins, which make urine more acidic.
Step-by-step explanation:
The alkaline ash diet influences urine pH by increasing its alkalinity. This happens because the consumption of certain foods, like monobasic and dibasic sodium and potassium phosphates, as well as a predominantly vegetarian diet, can result in the production of alkaline urine. The presence of monobasic phosphates tends to make urine more alkaline. The alkaline ash diet can be contrasted with acid-forming diets, typically high in protein from non-vegetarian sources, which make the plasma and consequently the urine more acidic.
It's also interesting to note that the timing of food intake affects urine pH. Urine collected immediately after eating is more likely to be alkaline due to the "alkaline tide," where bicarbonate ions are released into the blood during the digestive process. Overall, the urine pH can swing from a normal low of 4.5 to a high of 8.0, depending on these dietary factors. The balance of acid and base in the diet is critical, as chronic imbalances can contribute to health issues such as kidney stones or osteomalacia.