In terms of health, acid-base balance is now presented as an important indicator of the internal terrain. Not because it directly reflects blood pH – which remains extremely stable – but because it reflects the acid load that our lifestyle imposes on the body. Understanding this concept can shed light on certain metabolic or functional imbalances.

1. How does it work?

pH (potential of hydrogen) measures the acidity or alkalinity of a medium. It is expressed on a scale from 0 to 14, from most acidic to most basic, with a neutral point at 7.

The human body, composed of approximately 65% water, has different compartments, each with its own pH. The most monitored is blood pH (more precisely plasma), which remains remarkably stable: between 7.38 and 7.42. The body maintains this value through powerful systems: respiration, kidneys, and buffer systems. This pH varies very little, even when diet changes.

However, the quantity of acids the body must eliminate – called acid load – varies with our lifestyle habits. It is this load that can fluctuate, not blood pH.

2. Why is it important?

Our metabolism constantly produces acidic compounds. To maintain internal balance, these acids must be neutralized or eliminated. For this:

  • Pulmonary ventilation regulates the elimination of CO₂ (carbonic acid)
  • The kidneys eliminate non-volatile acids and regenerate bicarbonates

Diet directly influences the amount of acids that the kidneys must process. If it is very rich in "acidifying" foods, the body does not enter blood acidosis – but it increases its excretion effort. This is where the concept of PRAL (Potential Renal Acid Load) becomes useful: some foods increase this load, others reduce it.

3. What are the factors of acidity?

Our modern lifestyle tends to increase the acid load that the body must manage. Different factors contribute to this:

  • Intense lifestyles: stress, tension, mental overload, lack of sleep
  • Inappropriate lifestyle habits: sedentary behavior, tobacco, alcohol, pollution, chronic infections
  • Dietary excesses: animal proteins, processed foods, refined sugars
  • Emotional factors (TCM vision): rumination, fears, frustrations, anger

In TCM, these elements correspond to "internal loads" that maintain stagnation, heat, or organ tension. In modern physiology, they simply increase the amount of acids to be eliminated.

4. Regulation and measurement

Two main approaches can help regulate this acid load and restore a more balanced terrain:

Movement improves oxygenation, stimulates fluid circulation, and promotes metabolic elimination. Regular physical activity supports respiration and kidney function.

Diet provides alkalizing elements (minerals, vegetables) and reduces the overall acid load. There are many subtleties, but the PRAL classification provides a simple framework for guiding common choices.

Here is a practical breakdown, without claiming to modify blood pH, but aiming for better metabolic management.

5. Classification of acidifying & alkalizing foods

  • Acidifying, to be moderated: Animal proteins (meats/cured meats, fish/shellfish); Refined cereals (white rice, white bread); Dairy products; Sugar, sodas; Salt; Caffeine; Alcohol; Industrial condiments (ketchup, mayonnaise, mustard, chili, vinegar).
  • Alkalizing, to be favored: Lemon; Green vegetables (especially spinach); Potato, carrot, avocado; Fruits (including banana and prune); Mild spices (turmeric, ginger, black pepper); Aromatic herbs (coriander, parsley, arugula, lamb's lettuce); Seaweed; Water.

Since the kidneys are the main organs for acid elimination, it is possible to observe urinary pH to track the trend of the terrain. Urinary pH does not reflect blood pH, but it indicates the acid load that the body is eliminating at a given moment.

For this, reactive paper is used (available in pharmacies). Three measurements per day for five days allow for a reliable average:

  • 2nd morning urine (the first being naturally more acidic)
  • Before lunch
  • Before dinner

In a healthy individual, urinary pH ranges between 5 and 7.5. An ideal trend is generally between 6.2 and 6.8 in the morning, and between 6.8 and 7.5 in the evening.