Vitamin D deficiency in children is a health problem with social implications that must be considered unresolved. Indeed, since vitamin D is a fundamental factor in development of the musculoskeletal system, it is at the core of children’s growth. The primary action of vitamin D in childhood is to promote the proper formation of bone mass. Of note, 90-95% of vitamin D production is generated by exposure to sunlight, while only 5-10% comes from diet. Thus, deficiencies can occur if exposure to sunlight is inadequate.
In this regard, a British study evaluating data on the prevalence of rachitis caused by vitamin D deficiency found that cases of rickets in the UK have risen, especially during the last decade. This situation has been attributed to the fact that the ethnic component of the population living in the UK has probably undergone profound changes. Emergence of populations with darker skin tones has increased significantly, in which supplementation, even in the first year of life, has not been strongly recommended, which has brought about a greater risk of deficiency. In fact, darker phototypes do not allow complete absorption through exposure to sun and tend to require supplementation.
Vitamin D deficiency, however, is also possible in other countries such as Italy, where, although sun exposure is far more prevalent, the increase in the number of dark-skinned children has also been observed in the last decade. While some northern European countries often apply a policy of supplementing food with vitamin D (food fortification), resulting in a significant and widespread decrease in risk, lack of supplementation can increase the incidence of vitamin D deficiency. Therefore, in Italy as in other Mediterranean countries, lack of supplementation can also be a significant risk factor for vitamin D deficiency. Considering this, several scientific societies have established recommended dosages and timing for vitamin D administration in children that allows for adequate bone growth. However, during the first year of life even if administration is strongly recommended, there may be poor compliance, causing a marked increase in risk. Such risk may also be present at other stages of growth.