a) Either L-lactic acid or DL-lactic acid is just one of the forms that the lactic acid exists. Under the general condition, both are of the same physical and chemical property, and they are of different physiological effects to the human body for the opposite direction of optical rotation.

b) Proceeding from the method of production, for example, when the fermentation is adopted, the different bacteria and fermenting conditions will produce the optical isomers of L-lactic acid, D-lactic acid and a certain proportion of mixed DL-lactic acid. The synthesis may obtain the racemic DL-lactic acid only, where the two optical isomers of D and L account for 50% respectively, nearly zero at the optical rotation.

c) Proceeding from the application, for example in the food additive industry, L-lactic acid is easier to be absorbed in the human body and may directly enter into the internal metabolism without presence of acidosis, because the human muscle tissue itself contains the L-lactate dehydrogenase available for digestion of L-lactic acid. In such a case, the WHO proposes to restrict the addition of D or DL-lactic acid into the food for infant and pre-school children, but not to restrict the L-lactic acid. However, the L-lactic acid from fermentation shows too much difference in quality due to the application of different technique. Particularly, the product low at purity is unstable in quality and contains more impurities harmful to the human body. On the contrary, the product from synthesis is pure white in color, good at thermal stability and easier to control in quality; it has been extensively used in synthetical solvent.

d) So, we won't simply say which one is better among L-lactic acid, DL-lactic acid, fermented lactic acid and synthetic lactic acid. The proper judgment must be made only with reference to the specific field of application and product quality. However, the high quality L-lactic acid from JMB, except the pure natural lactic acid produced by means of fermentation, still features the two major properties of higher optical purity and higher purity, which has combined the advantages of fermentation and synthesis and is suitable to apply in every field.