Laminaria japonica Combined with Probiotics Improves Intestinal Microbiota: A Randomized Clinical Trial

Abstract

Laminaria japonica—a widely used ingredient in seaweed kimchi—and lactic acid bacteria (LAB)—a main component of traditional fermented Korean food—may alter human intestinal microbiota composition and have a positiveeffect on various digestive problems. However, few clinical trials have investigated the potential benefits of L. japonica when combined with LAB for human intestinal microbiota. Therefore, this study was designed to evaluate the effects of L. japonica and representative LAB on the human intestine. Forty participants with no known digestive diseases were randomly assigned to one of the two combination groups: (1) L. japonica with LAB and (2) L. japonica with placebo LAB. The study agents were administered for 4 weeks with a 2-week follow-up period. The primary outcome measure was the number of each of the seven LAB species in the human intestine, and the secondary outcome measures included the Korean version of the Gastrointestinal Symptom Rating Scale, the World Health Organization Quality of Life, and bowel functions. The primary outcome was evaluated before and after administration of the study agents (0 and 4 weeks), and the secondary outcomes were evaluated at 0, 4, and 6 weeks. Four of the seven LAB species were found to be significantly increased in the L. japonica with the LAB group and five species were significantly different from those of the placebo group. The secondary outcome measures did not change significantly. In conclusion, L. japonica with LAB facilitated the proliferation of beneficial human intestinal microbiota.