To the Editor.
—Although ascorbic acid sometimes is recommended1 and often used for urinary acidification, we are unaware of evidence establishing its efficacy. In fact, there is some evidence to the contrary.2 Skepticism that ascorbic acid, in the doses usually used, 1 to 2 g four times daily, is useful for this purpose, prompted a small controlled study in four healthy volunteers (three men and one woman) aged 24 to 38 years. All consumed a normal American acid-ash diet (about 100 mEq/day of acid) throughout the study.The pH of freshly voided urine, obtained at 3 to 4 PM, was measured daily using a pH meter for three or four days before ascorbic acid administration. Subjects then ingested 1 g of ascorbic acid orally at 8 AM and noon daily for seven days. On the third through seventh days, urine samples were obtained as just described and pHs