Fish oil as a dietary supplement usually has no strict time limit. Fish oil refers to fats and oils containing DHA and EPA, as well as other polyunsaturated fatty acids, extracted from lipid-rich fish in the ocean. Since these ingredients are beneficial nutrients, they can be used in moderation. The main components of fish oil are n-3 polyunsaturated fatty acids, such as DHA, EPA and linolenic acid, which are also found in natural foods such as perilla oil, flaxseed oil and walnut oil. Nutrient intake is usually not divided into breakfast, lunch and dinner or before and after meals, so there is no strict time limit for fish oil as a dietary supplement. Although fish oil can provide some nutrients for the human body, but it can not replace the natural diet, a variety of nutritional recommendations from the natural food intake as far as possible, if the intake is insufficient to consider dietary supplements.