The Human Gut Game: An Inquiry-Based Simulation That Teaches Students How Their Diet and Life Choices Influence the Diversity of Their Gut Microbiome

The human gut microbiome (GM) has been shown to rapidly evolve in one lifetime due to a change in diet. The relative abundance and richness of bacterial species in the human digestive tract is directly connected to a person’s diet, exercise, lifestyle, and use of antibiotics (Rinninella et al., 2019). Higher species richness and presence of certain species lead to better digestive health and can greatly reduce the risk of many gastrointestinal disorders, mood changes, hyperactivity in children, and obesity (De Filippo et al., 2010). Eating more fiber, less sugar, and less animal fat supports a diverse gut microbiome with bacterial species that help keep the lining of the small intestine functioning effectively (Rinninella et al., 2019). Higher levels of Firmicutes, such as Ruminococcaceae, and lower levels of Bacteroidetes, such as Bacteroidaceae and Bacteroides, have been connected with obesity (Wexler, 2007). A study of European children and African children showed that the African diet, rich in millet, sorghum, and local vegetables and lower in lipids and animal protein, selected for microbiota with high abundance of Prevotella and Xylanibacter, and low levels of Shigella and Escherichia (De Filippo et al., 2010). A greater ratio of Prevotella to Bacteroides has been shown to increase weight loss in humans on a high-fiber diet (Hjorth et al., 2019). Xylanibacter extracts energy from fiber well and provides protection from chronic inflammatory colonic disorders (Walsh et al., 2014). A transition from an omnivorous to a vegetarian diet is enough to drastically change the diversity and abundance of your microbiome (Huitzil, 2018). In one study where 10 young adults were given either a plant- or animal-based diet for five days, there was significant change in the GMs of the participants. Those given a plant-based diet had a higher colonization rate of species such as Roseburia spp., Eubacterium rectale, and Faecalibacterium prausnitzii. The animal-based diet resulted in colonization by species such as Bacteroides spp., Bilophila wadsworthia, and Alistipes spp. The animal-based diet caused the most structural damage to the gut lining and increased the risk of inflammatory bowel disorder (Quercia et al., 2014; David et al., 2014).

Digestive health is an uncommon topic in a high school introductory biology class. The biology curriculum usually includes a unit on the human body systems, which may cover the basics of the digestive system but is focused mostly on structure and function. Even a health education class might cover nutrition and the importance of healthy eating, but not many will dive into the physiological importance of maintaining a diverse gut microbiome. The immense effect of the human gut microbiome on the function of the human body is a relatively new area of research. There is much evidence to support the idea that your diet and lifestyle directly affect what species of bacteria occupy your digestive tract (Davenport et al., 2017; Quercia et al., 2014). The species composition, richness, and abundance of bacteria have been shown to control mood, focus in school, emotional responses, and susceptibility to many conditions such as irritable bowel syndrome (IBS), leaky gut, and obesity (Garud & Pollard, 2020). This lesson offers an active-learning approach to teaching high school students about the connection between their diet and their gut microbiome.

Traditional pedagogical approaches where the student learns passively in a teacher-centered classroom have been shown to reduce retention of the material in students and result in a lack of general interest in the topic (Michael, 2006). I designed this activity to be active and hands-on so that students are encouraged to engage more with the problem and make more connections on their own, an approach that has shown considerable promise. Instead of having the students listen to a lecture or present a research project, I created the Human Gut Game to simulate how the diversity of your gut microbiome would change based on your diet. Creating a competitive, fun, inquiry-based game engages students and drives meaningful discussion (Sengupta & Clark, 2016).

Students work in teams to outcompete their classmates in developing a model gut microbiome indicative of digestive health. The game simulates how diet and lifestyle affect the bacterial species that live inside your gut. These concepts were simplified in order to better engage high school students and to maximize understanding of the bigger picture. Ten bacterial species are represented in this game: three red bacterial species, which thrive with high-fat and sugary foods, and seven green bacterial species, which thrive with foods high in fiber and complex carbohydrates and low in animal fats.

The game follows a basic lesson on the structures of the digestive system, which includes the different structures and their roles in breaking down food to be absorbed by the bloodstream. This lesson should take a total of 60–80 minutes, depending on how long the discussions are. This is part of a larger unit on the systems of the human body. Students will be given a brief overview of the gut microbiome, including a short video (How the Food You Eat Affects Your Gut by Shilpa Ravella, 2017; https://www.youtube.com/watch?v=1sISguPDlhY).

Students should be divided into teams of two to three. Each team starts with a high diversity of bacteria, but as they choose which foods to eat, their bacterial diversity changes. In the beginning, the teams are asked to pick junk food or fast food options. This causes the number of “bad” bacteria to increase and the overall species richness to decrease. Teams are asked to pick three to five food cards in order to represent the variety of food they might eat for each meal in one day. Teams play five rounds and start to make healthier food choices in order to improve the number of “good” bacteria (Figure 1). Teams are also randomly assigned different life events, such as stressful situations and antibiotic prescriptions, that affect their bacterial diversity. There are analysis questions between rounds, to help students make connections, as well as reflection questions at the end of the game.

The objective of the game is to teach students how their food choices determine the environment in their gut, which then determines the diversity of their gut bacteria. The secondary goal is to get students to understand that their gut microbiome diversity impacts their overall health and behavior and can cause disease. This activity meets the Next Generation Science Standards HS-LS1-2, HS-LS1-3, HS-LS2-2, HS-LS2-6, HS-LS2-7, and HS-LS4-6.

Human Gut Game slideshow (in the Supplemental Material available with the online version of this article)

• Bacteria cards (available in the Supplemental Material online)

• Food cards

• Student handout

• One table for each team of students

• One larger table for the food station

• One table for the piles of bacterial species cards

• Two 5 gallon buckets

• Side effects cards

• Dice

The Human Gut Game was conducted with six introductory biology classes (grade 10) and one ecology class (grades 10–12) for a total of 79 students (ages 14–18). Based on the results from my reflection questions, 98% of the students stated that they enjoyed learning about the gut microbiome through this game. They explained that it was fun and interactive. Some expressed that the visuals appealed to their learning style. The learning objectives of this game were to improve understanding of how food impacts gut bacteria and how gut bacterial diversity affects human behavior and anatomy. These objectives appear to have been met, as shown by the student answers to the analysis questions: 95% of students demonstrated understanding of the connection between diet and diversity of bacterial species. In many of the written responses and conversations during the game, students commented on how the types of gut bacterial species directly affect how they feel and behave. Most of the students who did not understand this concept were using distance learning and had to watch the game through video. At this point, there is not a good alternative for remote education. Feedback from my colleagues was also very positive. They gave me some suggestions and were pleased with the engagement from the students. Some of the suggestions included adding small pictures of the bacterial species to the student handout and some other minor changes to the slideshow, which I fixed. Sample student responses are shown in Table 3.

Engaging students in learning about complex biological systems and relationships can be difficult. Creating opportunities for students to relax, compete, and make active choices helps to improve their focus and understanding. The Human Gut Game was successful in providing a differentiated approach to learning about the human body and this complicated relationship with bacteria. I was pleased with the level of comprehension by the students following the game and hope that it gives them the courage to make better choices surrounding their health. Additionally, through the implementation of this game, I hope that other biology teachers will be inspired and encouraged to create their own inquiry-based learning opportunities for their students.