DHA and AD can be taken together. DHA is usually derived from fish oil, and fish fat is rich in DHA, which is mainly involved in the development of the optic nerve and the brain, and plays a very important role in maintaining the normal function of the optic nerve and the brain. The main components of vitamin AD are vitamin A and vitamin D. Vitamin D promotes the absorption of calcium and phosphorus. Vitamin A in Vitamin AD is mainly responsible for maintaining night vision and promoting the development of optic cone cells, and is also involved in maintaining the function of the human skeletal and reproductive systems. Vitamin AD should not be taken by patients with vitamin D deficiency, hypercalcemia, hyperphosphatemia with renal rickets, and excessive amounts of vitamin AD can cause toxicity. DHA and AD are both fat-soluble. DHA is actually a polyunsaturated fatty acid. Vitamin A and vitamin D are fully soluble in all kinds of fat, including polyunsaturated fatty acids. There is no chemical reaction between them. In nature, they are often found together in a single food. For example, the liver of fish is rich in both vitamin A and vitamin D, as well as some DHA. The use of DHA and AD needs to require a doctor’s supervision.