Effects of the microalgae Chlamydomonas on gastrointestinal health
Algae are a highly diverse group of organisms capable of producing an abundance of bioactive compounds that can serve as functional food ingredients. Here we examine the effect of consuming whole-cell biomass of the green alga Chlamydomonas reinhardtii on gastrointestinal health in mice and humans. We first observed that mice were strongly protected against weight loss in a colitis model, losing only 12% of their initial body weight vs >20% for controls, when C. reinhardtii biomass was added to their diet during a 14-day trial. We then invited human participants to volunteer in a study investigating the effect of C. reinhardtii consumption with a focus on gastrointestinal health. Participants were provided lyophilized C. reinhardtii whole-cell biomass and asked to consume either 1 or 3 grams daily for 30 days. Throughout the study, participants reported changes in their gastrointestinal health through a custom-made questionnaire as well as providing up to three stool samples, once before the study and two during, to analyze any compositional change to their gut microbiome. We found that when individuals who frequently experienced gastrointestinal symptoms added C. reinhardtii biomass to their diet, they reported significantly less bowel discomfort or diarrhea, significantly less gas or bloating, more regular bowel movements, and better stool consistency. Analysis of participant stool samples suggested the gut microbiome composition in all groups remained complex and no signs of dysbiosis or adverse effect on microbial composition were observed.