Vitamin D3-enhanced Eggs 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: A double-blind controlled cluster randomized field trial was developed. The participants were children from 6 day-care centers (SEDESOL) at Cuernavaca, Morelos, Mexico. The study sample had 275 children that completed the study (the protocol considered having at least 125 children in each treatment group), from 12 to 59 months, who attended 6 take care centers (SEDESOL), in Cuernavaca, Morelos.
5. Objective To evaluate the efficacy of the consumption of fortified eggs with Vitamin D3 on the serum concentrations of 25-OH-D in children aged 12 to 59 months who attend take care centers (SEDESOL)in Cuernavaca.
6. Treatment and control groups: The random assignments of the intervention group (fortified egg) and control group (unfortified egg) were done considering each day-care center as a unit of allocation. Three day-care centers were randomized to the intervention group and three to the control group. The study lasted 12 weeks. The treatment group consumed a fortified egg to provide 10 mcg of Vitamin D3 equivalent to 400 IU of Cholecalciferol, 3 times a week. The control group received unfortified egg (~ 43 IU Vitamin D) with the same frequency as the intervention group.
7. Main Outcomes: The main outcome outcome variables were the serum levels of 25-hydroxyvitamin D3 (25-OH-D3) The second main outcome was to evaluate the parathyroid hormone (PTH). Other Variables: Blood parameters were taken: total cholesterol, HDL cholesterol, triglycerides, glucose, and hemoglobin. Anthropometric measurements of weight, height, age. Morbidity (diarrhea, constipation and respiratory tract infections) was evaluated three times per week and recorded. Standardized personnel weight the egg consumed before and after breakfast with a food weighing scale. Mothers were asked about children's usual diet by two diet questionnaires : a 24-hour dietary recall and a food frequency questionnaire at baseline and at the end of the study.
8. Ethical considerations:

The protocol was submitted to he Research and Ethics Committee of the Medicine Research Division of the National Autonomous University of Mexico.The study was approved on May 8, 2018 with folio FM/DI/028/2018.

The children's mothers or guardians signed an informed consent letter.