Effect of the Consuption of Vitamin D3-enhanced Eggs on Serum 25-hydroxivitamin D[(25-OH)D3] and Parathyroid Hormone (PTH) in Preschool Children

1. Vitamin D functions:

Vitamin D (VD) is a fat-soluble vitamin. Its main function is to maintain optimal levels of calcium and phosphorus in the body; it also helps in neuromuscular transmission and bone mineralization, important in bone health and growth in children. There are VD receptors in bone, bone marrow, adipose tissue, adrenal, brain, stomach, small intestine, colon, pancreas, liver, lung, muscle, activated B and T lymphocytes, and in other organs, tissues, and cells. For this reason, various functions are assumed. VD serum concentrations above 75 mmol/l (30 ng/ml) have been shown to keep cell growth under control and prevent cells from becoming autonomous and malignant. 2. Prevalences of vitamin D deficiencies and insufficiency:

Worldwide, a high proportion of children, youth, and middle-aged adults are deficient in Vitamin D. It has been estimated that about one billion people in the world may be deficient in Vitamin D.

In Latin America, only Mexico has representative population data on vitamin D deficiency. Recently it has been documented that the deficiency and insufficiency of Vitamin D are a public health problem in Mexico. In a national representative sample of 6,827 children aged 1 to 11 years who participated in the 2012 National Health and Nutrition Survey (ENSANUT), the prevalence of Vitamin D deficiency was 33% (25-OH-D <50 nmol/L), which means that there are 3 million children with Vitamin D deficiency in Mexico. On the other hand, insufficiency (25-OH-D of 50 <75 nmol/L) affects 56% of children. Likewise, it was found that less than 3% of children consume a supplement with Vitamin D. 3. Vitamin D intake recommendations in children:

The current vitamin D intake recommendations made by the APP since 2008 (Wagner CL, 2008) for children aged 1 to 8 years is an Adequate Intake of 400-600 IU (10-15µg), and for the Tolerable Upper Intake Level it is suggested do not exceed 2500 IU (63µg) in the case of children from 1 to 3 years and 3000 IU (75µg) in children from 4 to 8 years. 4. Description of the study: