Lack of exposure to sunshine.
There are some causes of Vitamin D deficiency.
1. The lack of sunlight exposure
2. The dark skin
3. The lack consumption of Vitamin D recommended level during the times.
Vitamin D deficiency is more common than mineral deficiency. Rickets is most common between six months and eighteen months. It can be caused by a deficiency of calcium, phosphorus, or vitamin D. There are 10 Ways Vitamin D Food Helps You To Stay Fit & Healthy!: bit.ly/2hJxuAg