Vitamin B6 is a key member of the essential B vitamin family, the squad responsible for helping your body (and cells) make energy and form red blood cells. B6 has a big job: it aids over 100 (!) enzyme reactions in your body. It’s also required to make neurotransmitters like dopamine, serotonin, and GABA—the ones that boost good feelings, confidence, and calmness—as well as the hormone melatonin for restful sleep; that means even mildly low levels of B6 can mess with your mood and ability to focus. You most likely get enough B6 from eating foods like chicken, fish, turkey, chickpeas, potatoes, and fortified cereals. You can also get B6, aka pyridoxine, from a supplement—it’s in most multivitamins, B complexes, or available on its own. If you’ve been diagnosed with or suspect an autoimmune disorder, it’s worth paying attention to B6 since the vitamin is directly related to immune function. Those with celiac disease, ulcerative colitis (UC), or inflammatory bowel disease (IBD) may have low B6 levels.