Vitamin D deficiency :
Vitamin D deficiency is characterized by reduced levels of vitamin D in human body, causing issues related to bones and muscles. The warning signs of vitamin D deficiency are mood changes, like depression, bone loss, muscle cramps and weakness, bone pain, especially in the back, deformities in the joints, and fatigue. These are the symptoms of rickets, which occur in case of severe vitamin D deficiency. Certain medications are known to decrease the levels of vitamin D in our body. Clinical conditions like cystic fibrosis, Crohn's disease, celiac disease, obesity, kidney disease and liver disease are also said to cause vitamin D deficiency in the body. Vitamin D deficiency can be rectified by taking foods that are rich in vitamin D like rainbow trout, beef liver, mushrooms, egg yolks, cod liver oil, fatty fish such as salmon and tuna, cow milk and soy, almond milk, breakfast cereals, orange juice and other dairy products such as yogurt.