In nutrition, the PRAL index is one of those indicators that is worth knowing about, especially if you are looking to optimise your diet in order to improve your recovery after exercise and boost your performance. And the good news is that the PRAL index is not that difficult to understand, even if you are not a sports nutrition expert like Benoît Nave, our boss on the subject at Baouw ! 

Also, after revealing the secrets of  chrononutrition and of the energy reserve, today, let's lift the veil on this indicator, which is still rarely mentioned in mainstream discourse, even though it is central to discussions about the acid-alkaline balance of our diet. This balance is particularly important for athletes who put their bodies under daily stress. But what exactly is it? And how can it be used wisely? Let's get started and explain everything.

What is the PRAL index?

The PRAL index stands for Potential Renal Acid Load. It is an indicator that estimates the net acid load that a food will produce in the body once metabolised, i.e. after digestion and assimilation. 

It's easy to understand: a positive PRAL index means that the food is acidifying, while a negative index indicates that it is alkalising. And it is this latter characteristic that we will seek to prioritise in the context of a sports diet, particularly as it helps to reduce inflammation. 

But where does this indicator come from?

The PRAL index was developed by Dr Thomas Remer and his colleagues in the 1990s. Its purpose was to provide an accurate assessment of the impact of foods on acid-base balance. It should be noted that just because a food tastes acidic does not mean it is acidifying! Lemon is a perfect example to illustrate this explanation, as it tastes acidic but is alkaline for the body. 

How is the PRAL index calculated?​

Quite simply, using a mathematical formula! Not a fan of maths? Don't worry, we'll explain the formula so you can understand the concept, but the aim isn't for you to whip out your calculator before every meal (we'll explain this in more detail below). Our famous PRAL index is calculated based on a food's protein, phosphorus, potassium, calcium and magnesium content. Why? Because these minerals and macronutrients influence the production of acid or base during metabolism.

Here is the simplified formula:

PRAL = 0.49 x protein (g) + 0.037 x phosphorus (mg) – 0.021 x potassium (mg) – 0.026 x magnesium (mg) – 0.013 x calcium (mg)

In other words, the more protein and phosphorus a food contains, the more acidifying it is. Conversely, potassium, magnesium and calcium have an alkalising effect. 

Why is the PRAL index important for your health?

The link between PRAL and acid-base balance

A brief overview of the human body to clarify matters. The human body constantly strives to maintain a stable blood pH level of around 7.4. If this pH level fluctuates too much, it can disrupt numerous metabolic functions.

PRAL index and prevention​

In this article, we will focus on the link between diet and exercise, but it is important to note that excess acidity promotes inflammation and can therefore have other repercussions on your body.

Which foods have a positive or negative PRAL?

Some examples of acidifying foods, those with positive PRAL

It is not a question of banning them outright, but of understanding their effect on the overall balance:

• red meat, oily fish
• processed cheeses, Parmesan (the cheese with the highest PRAL index)
• cereals and breads made from white flour
• white sugar
• walnuts, hazelnuts and peanuts
• soft drinks, ultra-processed foods

Some examples of basic foods, those with negative PRAL

For their part, these foods help neutralise acidity:

• lemon, grapefruit, banana, dates, and generally fruits rich in magnesium and potassium
• mainly green vegetables and colourful vegetables, such as sweet potato, carrots, beetroot, etc.
• almonds, Brazil nuts
• egg yolk
• curd cheeses
• sunflower and olive oils (choose first cold-pressed)
• Lima beans 

How can you use the PRAL index to balance your meals?

Please note, the idea is not to encourage you to calculate everything down to the last gram: it's about striving for overall balance. For example, the portion of 24-month-old Beaufort d'Alpage cheese that you enjoyed after your main course at lunch can be balanced out by a banana for dessert. Phew!

To optimise your acid-base balance, we encourage you to adopt the following habits: 

• Ensure you have more plant-based foods than animal products at every meal.
• Remember to combine protein sources with vegetables that are as fresh as possible.
• Prefer snacks rich in fruit and nuts, such as our energy bars and energy purees, with optimal acid-base balance.

We would like to emphasise one point: the PRAL index is not a tool to be used rigidly. However, understanding it can help you make the right choices, especially if you engage in intense physical activity or wish to adopt a more protective diet in the long term.

The limitations of this index 

It should be noted that the PRAL index does not take other complementary concepts into account. For example, it does not consider the matrix effect of foods in a meal does not replace a comprehensive approach to nutrition: food quality, glycaemic index, fibre intake, etc.

Our famous PRAL index is therefore a useful indicator for understanding the impact of eating habits on metabolism. But it should not be viewed in isolation from the broader context: it is not the PRAL index of a food that counts, but its overall nutritional profile and, by extension, your daily lifestyle as an athlete. If you incorporate the concept of the PRAL index into your meal planning (a bit like "marginal gains”), but you don't have a good ratio sleep/sport performance, your body will feel it, and you may find yourself chasing after your goals!

In summary: what you need to know about the PRAL index

• The PRAL index assesses the acid or alkaline load of a food in the body.
• A positive PRAL = acidifying food; a negative PRAL = alkalising food
• It is not a question of banning acidifying foods, but of finding the right balance.
• Fruit, vegetables and certain pulses are good allies for balancing PRAL.
• PRAL is one of many tools for eating better... and performing better.

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