Background/aim Vitamin D deficiency is widely prevalent worldwide. Vitamin D is known to be a key regulator of bone metabolism and is associated with muscle strength.

The objective of this study was to learn also about additional implications of vitamin D deficiency in adults and to investigate the extent of vitamin D deficiency in children worldwide, especially in a sunny country like Israel.

Methods The extent and severity of vitamin D deficiency, in adults and in children, were surveyed worldwide and especially in Israel, through a comprehensive review of previous reports and research studies done during the last 30 years in Israel and worldwide.

Results In adults, vitamin D deficiency has also been implicated in numerous health conditions including osteoporosis, cancer, diabetes, and autoimmune diseases.

In children, vitamin D deficiency was associated with metabolic syndromes and obesity. It was more prevalent in children who spend less time on outdoor activities, in obese children, and in cases when there was an imbalance between nutritional intakes and requirements. Vitamin D deficiency is common even in children living in sunny places like Israel.

Conclusion Vitamin D deficiency has many previously unknown implications.The doctors should be aware of the fact that although vitamin D deficiency is prevalent in the elderly population, it can also appear in the children, and can be associated with different illnesses. We encourage supplementation of vitamin D to special populations and encourage implementation of international food fortification programs.