Acid-Base Balance During Metabolic Processes in the Human Body

Acid–base homeostasis represents a dynamic equilibrium between cationic and anionic electrolytes within bodily fluids, a condition indispensable for the seamless execution of metabolic processes. The physiological pH range of blood, optimal for the majority of biochemical reactions, spans from 7.35 to 7.45, averaging 7.4. Deviations below 7.25 (acidosis) or above 7.55 (alkalosis) constitute critical disruptions to homeostasis, necessitating immediate corrective intervention. The primary acid-forming constituents include phosphate ions (PO₄³⁻), chloride ions (Cl⁻), and sulfate ions (SO₄²⁻), alongside incompletely metabolized organic acids such as oxalic acid (found in spinach), phytic acid (present in grains and seeds), and benzoic acid (a natural preservative in certain fruits). An additional contributor to acidification is the overproduction of carbon dioxide (CO₂), a byproduct of protein, lipid, and carbohydrate catabolism. Conversely, alkali-forming substances are predominantly cations of alkali and alkaline earth metals: potassium (K⁺), sodium (Na⁺), magnesium (Mg²⁺), calcium (Ca²⁺), and iron (Fe²⁺/Fe³⁺), which counteract excess acidity. Under physiological conditions, acid-forming components tend to predominate, a imbalance mitigated by three principal regulatory mechanisms: (1) the respiratory system (excretion of CO₂ via the lungs), (2) the renal system (elimination of excess acids and bases through urine), and (3) the blood buffer system (e.g., the carbonic acid–bicarbonate buffer H₂CO₃/HCO₃⁻). Nonetheless, the deliberate selection of dietary components—whose acid-forming or alkali-forming potential dictates the body’s long-term pH balance—remains a pivotal yet frequently overlooked factor in sustaining this equilibrium.