DHA, scientifically known as docosahexaenoic acid, is a very important unsaturated fatty acid for the human body, belonging to the ω-3 unsaturated fatty acid family of important members. Research has confirmed that DHA is a major component of the growth and maintenance of cells in the nervous system, and is an important component of the brain and retina, containing up to 20% in the human cerebral cortex and the largest proportion in the retina of the eye, accounting for about 50%, and is therefore essential for the intellectual and visual development of fetal infants. DHA can not be synthesized by the human body, it depends on external supplementation, and is easily decomposed in the stomach acid, so it is best to take it with meals or before meals. This period is a critical period for brain development, to 6 years old is generally close to the level of adults, and then supplementation is not very useful. In addition, different ages of babies need to supplement the DHA content is different, the older the need for more DHA. Excess DHA can have side effects, such as low immunity. Therefore, it is important to follow the doctor’s advice on how to take it.