Here’s what doctors and nutritionists want you to know about when and how to take calcium, plus how to know whether a calcium supplement is right for you. Those with health conditions that can cause malabsorption of nutrients, like celiac disease or Crohn’s disease, may also benefit from a calcium supplement, Dr. Litt added. However, what else you consume around the same time as your calcium supplement does matter. “Calcium supplements are best absorbed when taken in under 600-mg doses,” she said. The solution is also the same as with other supplements: Typically, your doctor will recommend spacing out your calcium supplement from when you take your medication.