Your body is a hotbed of bacteria, much of it beneficial and essential. Most of these bacteria reside in the gut, outnumbering your body’s cells by 10 to one. According to Harvard Medical School, your bowels are home to an estimated 100 trillion microorganisms covering more than 500 species, including mostly bacteria, but also viruses and yeasts.

These microorganisms are found in your large intestine and play an important role in a number of body systems and functions. The microbiota manufactures vitamin K and some B vitamins, and it turns fibers into short-chain fats that feed the gut wall and perform a variety of metabolic functions, earning it the nickname “the forgotten organ” by scientists.

Imbalances in the gut flora are linked to diseases like obesity, type 2 diabetes, metabolic syndrome, colon cancer, depression, heart disease, and Alzheimer’s disease. It can also cause myriad digestive woes, including inflammatory bowel diseases like ulcerative colitis and Crohn’s disease.

A healthy balance of gut bacteria is linked to a wide range of health benefits, including improved digestion and immune function, healthier skin, weight loss, and a reduced risk of a number of diseases. Balancing the gut microbiota is largely a matter of ingesting probiotics.