It might sound confusing that fruits high in citric acid can turn your urine less acidic, but the acid in foods doesn’t necessarily equate to more acid in your body’s metabolic processes. That has to do with how much protein, phosphorus, potassium, magnesium, and calcium are being consumed, all of which contribute to the potential renal acid load, or PRAL. High PRAL scores mean high acidity, and low or negative PRAL scores mean the food is more alkaline.
Protein and phosphorus in foods make your body more acidic and can stress your kidneys, whereas potassium, magnesium, and calcium bring your body’s acid levels down. A cup of pineapple has a PRAL score of minus 3.67, which helps create a less acidic environment in your body and so decreases your risk of kidney stones. Compare that with a roasted chicken leg, which has a PRAL score of 33.33. Generally speaking, fruits and vegetables tend to have a negative PRAL score, which is good for your kidneys.