1. Introduction
VD deficiency, cancer, chronic diseases, asthma, allergic diseases
RESPIRATORY TRACT INFECTIONS, TYPE 1 DIABETES, CANCER, CHRONIC DISEASES, ASTHMA, CARDIOVASCULAR DISORDERS
Vitamin D (VD) deficiency (serum 25(OH)D < 50 nmol/L) affects 27.3% of preschool children in Mexico. The purpose of this study was to assess the effect of vitamin D supplementation at different doses on serum 25(OH)D concentrations in preschool children. In a randomized control trial, 222 children 12–30 months old were randomly assigned to one of four treatment groups: (1) Vitamin D2 (Ergocalciferol) 400 IU/day (Vitamin D (VD) is an essential nutrient in humans, which can be synthesized in the skin after exposure to UVB sunlight rays [In addition to its role in bone health, VD is of importance for many metabolic and physiological processes. Conversely, VD deficiency has been associated with unfavorable outcomes for human health, among which are autoimmune and allergic diseases such as type 1 diabetes, asthma, respiratory tract infections, chronic diseases such as several types of cancer, and cardiovascular disorders [It is estimated that VD deficiency (<50 nmol/L of 25(OH)D) is a global problem affecting approximately one billion people. Some possible factors associated with VD deficiency are less sun exposure and outdoor physical activity, increased BMI, and use of sunscreen [A number of studies have assessed the effects of VD supplementation. In Italy, a study in children ages 2–15 years with moderate VD deficiency showed that a 1500 IU dose of vitamin D3/day for six months was appropriate for children to maintain normal to near-normal 25(OH)D levels [Routine, widespread VD supplementation in children has not been implemented in Mexico. Therefore, the objective of the present study was to evaluate the efficacy of supplementation with 400 IU or 800 IU of vitamin D2 and 1000 IU of vitamin D3 for three months on serum 25(OH)D levels and the prevalence of VD deficiency in children from 12 to 30 months of age.