AgroParisTech, CRNH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, 16 rue Claude Bernard, F-75005 Paris, France.
Clin Nutr. 2012 Jun;31(3):313-21. doi: 10.1016/j.clnu.2012.01.006. Epub 2012 Feb 18.
Net acid production, which is composed of volatile acids (15,000 mEq/day) and metabolic acids (70-100 mEq/day) is relatively small compared to whole-body H⁺ turnover (150,000 mEq/day). Metabolic acids are ingested from the diet or produced as intermediary or end products of endogenous metabolism. The three commonly reported sources of net acid production are the metabolism of sulphur amino acids, the metabolism or ingestion of organic acids, and the metabolism of phosphate esters or dietary phosphoproteins. Net base production occurs mainly as a result of absorption of organic anions from the diet. To maintain acid-base balance, ingested and endogenously produced acids are neutralized within the body by buffer systems or eliminated from the body through the respiratory (excretion of volatile acid in the form of CO₂) and urinary (excretion of fixed acids and remaining H⁺) pathways. Because of the many reactions involved in the acid-base balance, the direct determination of acid production is complex and is usually estimated through direct or indirect measurements of acid excretion. However, indirect approaches, which assess the acid-forming potential of the ingested diet based on its composition, do not take all the acid-producing reactions into account. Direct measurements therefore seem more reliable. Nevertheless, acid excretion does not truly provide information on the way acidity is dealt with in the plasma and this measurement should be interpreted with caution when assessing acid-base imbalance.
与全身 H⁺ 转换（150,000 mEq/day）相比，净酸生成量相对较小，由挥发性酸（15,000 mEq/天）和代谢酸（70-100 mEq/天）组成。代谢酸来自饮食摄入或作为内源性代谢的中间或终产物产生。净酸生成的三个常见来源是硫氨基酸代谢、有机酸的代谢或摄入，以及磷酸酯或膳食磷蛋白的代谢。净碱生成主要是由于从饮食中吸收有机阴离子所致。为了维持酸碱平衡，体内通过缓冲系统中和摄入和内源性产生的酸，或通过呼吸（以 CO₂ 的形式排泄挥发性酸）和尿（排泄固定酸和剩余 H⁺）途径将其从体内排出。由于酸碱平衡涉及许多反应，因此酸生成的直接测定较为复杂，通常通过酸排泄的直接或间接测定来估计。然而，间接方法是根据饮食的组成来评估其形成酸的潜力，并未考虑所有产酸反应。因此，直接测量似乎更可靠。尽管如此，酸排泄并不能真实反映血浆中酸度的处理方式，在评估酸碱失衡时，应谨慎解读该测量结果。
