Western diets are not responsible for chronic acid retention: a critical analysis of organic acid and phosphate contribution

Abstract

According to usual literature, the diet-dependent endogenous production of titratable acidity (TA) is contributed by sulphuric and phosphoric acids (NA) and by metabolizable acids (MAs), representing ‘net-endogenous acid production’ (NEAP). NEAP is mainly neutralised by diet-dependent salts of inorganic cations (), estimated in foods, faeces and urine from inorganic cation–anion difference (NB). It is claimed that urinary loss of organic acids’ anions, ‘’, induces metabolizable H+ ions’ retention. Since ‘’ is normally lost in urine as ‘’ or ‘’, no MA retention takes place. Therefore, in our approach, net acid production (NAP) reduces to endogenous sulphuric acidity only. Since in western diets (WDs) alkaline cations exceed inorganic anions (NB excess), acid excess from phosphorus is neutralized. Moreover, the renal reabsorption of ultra-filtered Pi takes place at ratios greater than ‘4/1’, which means that the kidney operates as a dietary Pi-dependent NB generator ( or ). Since, in standard WDs, H2SO4 generation is less than ‘’ production, the sulphuric acidity escaping the intestinal absorption is neutralized by and excreted as diet-dependent , without interfering in normal A/B status. Only when extreme acidifying diets are ingested, sulphuric acidity may exceed ‘’. In this case, the excess of sulphuric acidity production is neutralised by the intervention of urinary excretion, whose employment is normally restricted to prevent loss of ultra-filtered NB. Finally, the whole body NA balance (NAb(W)) is calculated from the difference ‘NAabs – NA(u)’, where abs = intestinal absorption and u = urinary excretion. Being ‘NAabs ≈ NA(u)’, NAb(W) approximates zero, confirming WDs as non-acidifying foods.