To the Editor We read with interest the article by Lane et al1 who reported on the effects of 1 g of benzoic acid as an augmentation strategy for patients with chronic schizophrenia. The article did not mention whether dietary intake of benzoic acid was monitored or controlled before or during the study. High levels of benzoic acid have been reported in salted fish, soy sauce, and juices,2 with the largest proportion of intake from the consumption of water-based flavored drinks,2,3 which may have benzoic acid concentrations as high as 0.35 g/L3. A survey identified high levels of consumption of water-based flavored drinks in Taiwanese teenagers (approximately 2.5 L/wk),4 and consumption of soy foods in Taiwan has been estimated at 13 kg per person per year.5 Differences in participants’ dietary benzoic acid intake may be a significant confounding variable that needs to be considered in interpreting the outcome of this study and in designing future studies.
Glue P, Gale C, Parnell W. Impact of Dietary Benzoic Acid on Treatment Response in Schizophrenia. JAMA Psychiatry. 2014;71(11):1298-1299. doi:10.1001/jamapsychiatry.2014.673