Acid-Base Balance: The Most Effective Dietary Supplements

The human body has sophisticated systems that keep blood pH within an extremely narrow range, between 7.35 and 7.45. This maintenance is essential for survival because slight variations can severely disrupt cellular functions. Several mechanisms are involved in ensuring this balance: • Chemical buffers: The bicarbonate system is the primary buffer in the blood. It neutralizes pH changes by capturing or releasing hydrogen ions (H⁺). • The lungs: They remove volatile acids, mainly carbon dioxide (CO₂), which is converted into carbonic acid in the blood. Increased breathing expels more CO₂, thereby raising pH. • The kidneys: These organs regulate fixed (non-volatile) acids by reabsorbing bicarbonate and excreting H⁺ ions in the urine. Urinary pH is therefore a dynamic measure that reflects the kidneys' effort to maintain balance, but it does not necessarily reflect blood pH.

Urinary pH and acid-base balance

The human body is made up of several physiological compartments, each with a specific pH adapted to its biological functions. These compartments mainly include blood, interstitial fluids, cells, and digestive juices. The blood pH, maintained within a narrow range of 7.35 to 7.45, is the most tightly regulated because a variation, even slight, can disrupt enzymatic functions and lead to serious dysfunctions. In contrast, other compartments, such as urine or gastric fluids, have much more variable pH values depending on their role. Urine, for example, has a pH that can range between 4.5 and 8, depending on the kidneys' needs to excrete acids or bases. This fluctuating pH reflects the body's capacity to regulate its acid-base balance more than it directly indicates blood pH. Likewise, gastric fluids are very acidic, with a pH between 1.5 and 3, necessary for digesting food and protecting against pathogens. Conversely, intracellular pH, slightly acidic, averages around 7.2, which allows cells to maintain their metabolic activities. This compartmentalization of pH is essential to optimize the specific functions of organs while minimizing potential disturbances between systems. For example, the bicarbonate buffering system in the blood acts to neutralize pH fluctuations related to respiration or metabolism without interfering with the acidic conditions necessary for digestion in the stomach. Contrary to a common belief, urinary pH is not a direct indicator of blood pH. It varies considerably depending on diet, physical activity, and the body's regulatory needs. An acidic urinary pH is often the result of excreting excess metabolic acids to maintain blood homeostasis. However, regularly measuring urinary pH can provide clues about overall trends in acid-base metabolism.

Acidosis: reality or exaggeration?

The idea that the modern diet causes chronic acidification of the blood is simplistic and inaccurate. The body has robust mechanisms to prevent metabolic acidosis. However, a diet high in acidifying foods can increase the acid load the kidneys must handle, which could contribute in the long term to mineral imbalances or problems such as osteoporosis. There are three major causes of acidification that deserve particular attention. First, diet plays a major role in acidification. Foods high in animal protein, such as meat, and acidifying beverages like alcohol, wine, or coffee, produce acidic residues after metabolism. These acids must be buffered by regulatory systems, mainly the kidneys, to maintain acid-base balance. Excessive consumption of these foods, combined with inadequate intake of alkalinizing foods such as fruits and vegetables, can increase the acid load. Next, stress is another important source of acidity. During periods of strain, muscles produce metabolic acids such as lactic or sulfuric acid. These substances, when not eliminated effectively, accumulate in tissues, exacerbating feelings of fatigue or pain. This situation requires the kidneys to eliminate excess acid through the urine, often observed as a low urinary pH. Finally, infections can also cause transient acidification. When an infection develops, cellular and immune metabolism accelerates, producing more acidic residues. This phenomenon can precede the classic symptoms of an infectious disease such as influenza or bronchitis, where transient acidosis reflects the body's struggle to restore balance.

Diet and acid-base balance

Foods are not classified by their taste (acidic or basic) but by the metabolic residue they leave after digestion: • Acidifying foods: Red meats, cheeses, refined grains, sugar, and alcohol. • Alkalinizing foods: Fruits, green vegetables, almonds, and bicarbonate-rich waters. • The citrus paradox: Although they taste acidic, fruits like lemon leave an alkaline residue in the body after metabolism.

Practical solutions

An acid-base imbalance can have significant health repercussions. When acidity predominates, even locally, it can promote chronic inflammation, joint or muscle pain, and a decrease in bone mineral density. This imbalance can also impair the efficiency of enzymes and metabolic processes, thereby slowing recovery after exertion or increasing fatigue. From a dietary standpoint, incorporating more alkalinizing foods, such as fresh fruits and vegetables, nuts, and mineral waters rich in bicarbonates, helps reduce the acid load. These foods provide the bases needed to buffer the acids resulting from consumption of animal proteins or refined sugars.Moderate and regular physical exercise is also crucial. By stimulating blood and lymph circulation, it helps eliminate accumulated acids and strengthen the body's buffering systems. Physical activity, combined with proper hydration, supports the kidneys in their function of eliminating acidic residues through urine. Finally, relaxation or meditation practices can reduce stress-related acidity and contribute to an overall sense of well-being.