Lactic acid bacteria as probiotics for human and animal have developed into a major research focus area. Product applications include several commercially successful functional foods, health supplements as well as therapeutic components and preparations. Cutting age methodologies, such as molecular approaches for the identification and quantification of intestinal probiotics, maintaining viability of probiotics under processing and storage conditions, and markers for modulation of host immunity and physiology functions have been developed. Therefore, it is timely to update the scientific research and clinical studies, and to search for future directions.