L. Casei is a strain of the lactic acid bacterium Lactobacillus casei, a microbe native to the human gut. It passes through stomach acid intact and attaches to the intestinal lining. Manufacturers add it to fermented dairy foods and probiotic supplements to promote digestive balance.
People use this strain to support digestion and immune health, particularly during or after a course of antibiotics. It can help keep bowel movements regular and reinforce the guts natural defenses. Taking it with a meal improves its survival through the digestive tract.
Most healthy adults can take it without problems. Those with compromised immune systems or severe short bowel syndrome should stay away from live bacterial supplements. At first, some people notice mild bloating or gas.