Lactobacillus casei is another species of lactobacillus, a vast grouping of micro organisms, or bacteria that contains many species. Lactobacillus casei is most beneficial to human health in a number of ways. L. casei have been found to be quite useful in treating gastrointestinal issues, patients with chronic constipation saw better improvement when taking any beverage or drink which contains the lactobacillus casei strain. The most common diet of L. casei is yogurt.