Vitamin D is important in both phosphorus and calcium metabolism as it helps ensure the enough levels of these minerals for metabolic functions and mineralization of the bones. One effect of not having enough vitamin D is rickets. Up until the present, the deficiency in vitamin D is the major cause of rickets among infants in most countries. Studies by Pettiflor and his colleagues (2004) showed that climatic conditions that prevent ultraviolet exposure and low dietary intake of vitamin D can be attributable to such disease in toddlers. Interestingly, in sunny countries like Bangladesh and Nigeria, such occurrence of rickets is not well observed.