What is "Potential Renal Acid Load" (PRAL)?

November 16, 2023

Potential renal acid load (PRAL) is a method used to estimate the potential acidity of a diet based on the balance of acid-forming and base-forming foods. The PRAL of a food is calculated by measuring the amount of acid that it produces after being metabolized (processed) in the body.

When we eat food, it is broken down and metabolized in the body, and this process can result in the production of acids or bases. Acid-forming foods are those that produce more acid than base, while base-forming foods are those that produce more base than acid. The PRAL of a diet is the balance between these acid-forming and base-forming foods.

The PRAL formula is used to estimate the potential renal acid load of a diet. The formula takes into account the acid-forming potential of the food based on its content of protein, phosphorus, potassium, magnesium, and calcium. The formula is as follows:

PRAL (mEq/day) = 0.49 x protein (g/day) + 0.037 x phosphorus (mg/day) - 0.021 x potassium (mg/day) - 0.026 x magnesium (mg/day) - 0.013 x calcium (mg/day)

In this formula, the values for protein, phosphorus, potassium, magnesium, and calcium are obtained by analyzing the nutrient content of a food using a nutrition database or laboratory analysis.

A positive PRAL indicates that a diet is acid-forming, while a negative PRAL indicates that a diet is base-forming. A high PRAL has been associated with increased risk for several health conditions, such as osteoporosis, kidney stones, and hypertension.

To lower the PRAL of your diet, you can focus on consuming more base-forming foods, such as fruits, vegetables, and legumes, and reducing your intake of acid-forming foods, such as meats, cheeses, and processed foods.

Foods with a low acid load are those that are considered base-forming and can help balance the acid-base equilibrium in the body. Some examples of foods with a low acid load include:

  1. Vegetables: Almost all vegetables are base-forming, including leafy greens like spinach, kale, and collard greens, as well as cruciferous vegetables like broccoli, cauliflower, and cabbage.
  2. Fruits: Most fruits are also base-forming, including citrus fruits like lemons and oranges, berries like strawberries and blueberries, and tropical fruits like bananas and papayas.
  3. Legumes: Legumes like beans, lentils, and chickpeas are also base-forming and can be a good source of protein for a low-acid diet.
  4. Nuts and seeds: Nuts like almonds and seeds like chia and flaxseeds are base-forming and can provide healthy fats and other nutrients.
  5. Whole grains: Whole grains like brown rice, quinoa, and oats are base-forming and can be a good source of complex carbohydrates.

It's worth noting that even some foods that are typically considered acidic, like citrus fruits, can actually have a base-forming effect on the body due to the way they are metabolized. Ultimately, a balanced diet that includes a variety of whole foods can help keep the acid-base balance in check.

When creating a low acid load recipe for chronic kidney disease, it is important to focus on foods that are lower in protein and phosphorus, as these are the nutrients that can contribute to a high acid load. Here's an example of a low acid load recipe for chronic kidney disease:

Tofu and Vegetable Stir-Fry


  • 1 block (14 oz) of firm tofu, drained and pressed
  • 1 cup green beans, trimmed and cut into bite-sized pieces
  • 1 cup broccoli florets
  • 1 cup sliced bell peppers (red, green, and/or yellow)
  • 1/2 cup sliced onions
  • 2 cloves garlic, minced
  • 1 tablespoon grated fresh ginger
  • 2 tablespoons low-sodium soy sauce
  • 1 tablespoon rice vinegar
  • 1 tablespoon toasted sesame oil
  • 1/4 cup chopped fresh cilantro


  1. Cut the tofu into bite-sized cubes and set aside.
  2. In a large wok or skillet, heat the sesame oil over medium-high heat.
  3. Add the green beans, broccoli, bell peppers, onions, garlic, and ginger to the wok, and stir-fry for 5-7 minutes, until the vegetables are crisp-tender.
  4. Add the tofu to the wok and stir-fry for an additional 2-3 minutes, until the tofu is heated through.
  5. In a small bowl, whisk together the soy sauce and rice vinegar, then pour the mixture over the stir-fry and toss to combine.
  6. Serve the stir-fry hot, garnished with fresh cilantro.

This recipe is low in protein and phosphorus, as well as being rich in base-forming vegetables like green beans, broccoli, and bell peppers. The use of tofu as a protein source also helps to keep the acid load low. The low-sodium soy sauce and rice vinegar provide flavor without adding excess sodium, which can also be an issue for people with chronic kidney disease.

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