"So vitamin D deficiency in children can start at a very early age which we call as rickets. But along with vitamin D deficiency most of them will also present with signs and symptoms of calcium deficiency too. So signs and symptoms will include as early as delayed in teething teeth will start erupting at a later age there will be delay in walking you can usually compare it with a sibling his elder child would have walked at a early age but the younger sibling might having a delay in walking. In more pronounced cases we do also see deformities in the knees. Usually there will be curbed knees. These are all signs and symptoms of vitamin D deficiency . Other changes will be there will be poor weight gain that almost the growth will be stunted and older children will complain of muscle pains and bone pains especially at night. How do we treat this and how do we avoid this is a good amount of sunshine always for vitamin D deficiency it will help. So sunshine with physical activity. So allowing them to have a daily physical activity especially sports will help in avoiding vitamin D deficiency. Along with that good diet and nutrition. Some of sources of vitamin D along with sunshine is sundried mushrooms, milk dairy products like cheese. Some fatty fish like salmon mackarel. Sardines will also help in getting good source of vitamin D"