There is no strict time requirement for taking vitamin D. It is usually best taken after meals. Vitamin D is a fat-soluble vitamin, generally dissolved in fat solvents, fats or organic solvents, chemically stable, and not easily oxidized in neutral or alkaline solution environment. It is chemically stable and is not easily oxidized in neutral or alkaline solution environments. However, it is gradually broken down in acidic solution environments, thus affecting the absorption of its components. Vitamin D pharmacokinetics show that vitamin D needs to be bound to fat and is absorbed mainly in the jejunum and ileum sites. Vitamin D binds to celiac particles, favoring the absorption of its nutrients. It can be seen that when vitamin D is taken on an empty stomach or before a meal, stomach acid will have a great impact on the absorption of vitamin D. When vitamin D is taken after a meal, the dietary celiac fats and oils are favorable for the absorption of vitamin D. Therefore, vitamin D should be taken after meals. Pharmaceutical vitamin D must be used under the guidance of a doctor.