Are you constantly feeling sick or fatigue? Does your back pain is not leaving you alone? If yes, you are probably suffering from vitamin deficiency. Vitamin D is an essential nutrient for our body. It helps in the absorption of calcium in the body, which is important for our bones to be strong and healthy. Vitamin D also helps in blocking the secretion of parathyroid hormone, which reabsorbs bone tissue and makes bones thin and brittle. This nutrient plays a significant role in the muscle and immune function as well. This clearly means that it protects us from various ailments. To make sure that you have enough of this vitamin in your body, add foods like cod liver oil, salmon, orange juice, yogurt, egg yolk, cereal, cheese etc. Deficiency of vitamin D can potentially cause problems like kidney and liver disease, cystic fibrosis, celiac disease, obesity etc. Here, we tell you about the factors that may be responsible for vitamin D deficiency.