I. What is the role of DHA? 1. To the fetus: The fetus needs to rely on DHA to optimize the development of visual and cognitive functions. In late pregnancy, DHA is preferentially absorbed by the rapidly developing brain and enriched in the gray matter of the brain and retina. 2. For pregnant mothers: Appropriate intake of DHA by women during pregnancy may reduce inflammation-related diseases such as preterm labor, preeclampsia, and allergic/atopic disorders in offspring. Second, where does DHA come from? 1. Fish (including finfish and shelled aquatic animals) is a healthy food low in saturated fat and rich in protein, and is also a major dietary source of DHA and EPA. 2. Fish oil or seaweed oil supplements. How to supplement DHA? 1. For women who are preparing for pregnancy, are pregnant or are breastfeeding, the global expert group recommends that the minimum intake of DHA should be 200-300mg/d. 2. Pregnant women should consume 2-3 servings of fish per week. 3. Since most pregnant women’s fish intake does not meet the expert group’s recommended level of DHA intake, it has been suggested that pregnant women should consume n-3LCPUFA supplements (e.g., fish oils or supplements derived from algae) or n-3LCPUFA-fortified foods. For women who are unable or unwilling to consume fish, these products are alternative sources of DHA and EPA, but their effects may not be exactly equivalent. IV. Is DHA supplementation safe? 1. Because fish intake by pregnant women may expose the fetus to methylmercury and other environmental contaminants found in fish, the guidelines for fish intake during pregnancy emphasize the selection of fish that are low in mercury and high in DHA. Mercury is present in all fish tissues, cannot be removed by cooking, and is absorbed by the mother’s gastrointestinal tract at a rate of over 95%. 2. The fetal brain is now known to be the most vulnerable tissue to mercury. Fetal exposure to methylmercury can cause diffuse and widespread neurological damage, such as the community-wide mercury poisoning that occurred in Japan (Minamata disease) and Iraq. In these communities, pregnant women exposed to high levels of methylmercury were asymptomatic themselves, but their children had developmental delays and, in some cases, extremely severe neurological deficits, including blindness, deafness, and cerebral palsy. 3. Fish oil supplements are virtually free of mercury because fish oil is usually derived from small pelagic fish used to make fish feed or from seaweed preparations. Also, most fish oil supplements have been purified to reduce environmental toxins to negligible levels. However, supplements can cause some unpleasant side effects, most commonly gastrointestinal disturbances (such as nausea), and fish oil supplements can also cause belching (burping) followed by a “fishy” odor, bad breath, heartburn, and sweaty odors. Fifth, the precautions of DHA supplementation 1, containing fish oil or algae DHA supplements have a variety of dosage options, it is recommended to choose the preparation for pregnant women. 2, EPA and DHA content varies from product to product. These products also contain other n-3LCPUFA, monounsaturated fats, saturated fats, gelatin, or glycerol; in a 1000mg fish oil capsule, the content of DHA and EPA is usually ≤500mg. 3, Cod liver oil has a high content of EPA and DHA, but it is not as good as other fish oils because it contains Vitamin A, which has a teratogenic effect when used in large doses. 4, if fish oil supplements produce a fishy odor, they can be frozen and stored, replaced with other preparations, taken with meals, or change the time of intake. 5. There are many DHA-fortified foods available, including yogurt, milk, eggs and cereals. However, many fortified foods contain plant-based n-3LCPUFA (ALA) rather than marine n-3LCPUFA, which cannot be used as a substitute for EPA and DHA because of their low conversion rates. The quality of fish oil supplements varies, and there are no regulatory agencies that adequately monitor them to ensure that the EPA and DHA content of the product is consistent with the label.