Lactobacillus casei, a species of lactic-acid bacteria, is known for its probiotic properties and ability to improve gut health. Synonyms for this beneficial bacterium include Lactobacillus paracasei, Lactobacillus rhamnosus, Lactobacillus zeae, and Lactobacillus fermentum. These synonyms reflect different strains or subspecies of Lactobacillus casei that have been identified and studied for their potential health benefits. Some of these strains have been shown to boost the immune system, support digestion, and alleviate symptoms of irritable bowel syndrome. With the growing interest in probiotics and their role in promoting overall health, research on different Lactobacillus casei strains is ongoing to determine their specific benefits and applications for human health.