Your body is loaded with trillions of bacteria. Paired with other tiny organisms like viruses and fungi, they make what’s known as the microbiota, or the microbiome. The mix of bacteria in your body is unique to you. It’s determined partly by your mother’s microbiota and partly by your diet and lifestyle. Between 300 to 500 different kinds containing nearly 2 million genes live in your gut. They line your entire digestive system, but most live in your intestines and colon. They help process food and affect everything from your metabolism to your mood to your immune system. They may be tied to your risk of diabetes, obesity, depression, and colon cancer.