A Critical Review of “A randomized trial of the effects of the no-carrageenan diet on ulcerative colitis disease activity (Nutr. Healthy Aging. 2017; 4(2): 181–192).”

Carrageenan (CGN) is a widely used food additive commonly found in dairy products, dairy substitutes (such as almond milk and soy milk), deli meats, nutritional supplements, beverages, and infant formula. It is typically used as a gelling, thickening, emulsifying and stabilizing agent and to improve the mouthfeel of the product. Decades of research on CGN safety has been reviewed by numerous regulatory bodies across the world. These regulatory bodies have all agreed on the safety status of CGN used as a food additive. Despite this, a few groups have continually published reports using misinformation and misinterpretation of results to suggest that CGN is harmful. The study reviewed here, “A randomized trial of the effects of the no-carrageenan diet on ulcerative colitis disease activity (Bhattacharyya et al. Nutr. Healthy Aging. 2017; 4(2): 181–192)” from Joanne Tobacman’s group, is an example of this. In this study, Bhattacharyya et al. set out to assess the impact of CGN in the diet on the interval to relapse in patients with ulcerative colitis (UC) who were currently in remission. For the study, UC patients in remission were instructed to participate in a “no carrageenan” diet. Some of the participants also received placebo capsules while others received CGN capsules. CGN, being a food additive, is mostly ingested as part of the diet, and typically bound to food protein. It is never ingested as a bolus in capsule form. The study contains errors in the interpretation of CGN literature and has cited studies that used degraded CGN, not food grade CGN. There are also issues with the use of statistical tests and data interpretation. In one instance, the authors seemed to ignore their own study results, suggested that CGN in the diet had no effect. Here we will review these issues as well as discuss how this study could have been approached to eliminate obvious bias.