What are the signs of calcium deficiency? RD Natalie Allen weighs in. February 28, 2019 by University CommunicationsCalcium is a mineral our body needs to maintain strong bones and teeth. It also helps our muscles, nerves and heart to function properly. So what are some signs that a person lacks calcium? Natalie Allen, a registered dietitian and clinical instructor of biomedical sciences at Missouri State University, shares with INSIDER a couple of signs to look out for.