There is no best calcium supplement for 4 year olds. 4 year olds who are clearly diagnosed with calcium deficiency can follow the doctor’s instructions to apply organic calcium, such as calcium lactate and calcium gluconate for calcium supplementation. 1. Calcium Lactate: Calcium Lactate can also be used for the prevention and treatment of calcium deficiency, commonly used dosage forms are tablets, granules, oral solution, etc., need to follow the doctor’s advice in accordance with the dose of children, but hypercalcemia, calcium-containing renal calculi, or patients with a history of renal calculi are prohibited. 2. Calcium gluconate: mainly mineral medicine, can prevent and treat calcium deficiency, suitable for children, women, the elderly and other people, but allergic to the product is prohibited, allergic people use with caution. 4-year-old children in the case of calcium deficiency, in addition to cooperate with the doctor to choose drugs to supplement, but also in the dietary aspects of regulation, eat more calcium-rich foods, such as pork ribs, chicken soup, etc., to maintain a balanced diet and nutrition, do not picky partiality.