An examination of parental compliance with vitamin D recommendations and the physiological responses to vitamin D isoform and dosage in breastfed infants from greater Montréal
Notice bibliographique
Résumé
Vitamin D is important to maintain calcium homeostasis and promote healthy bone development. Breastfed newborns are at heightened risk of vitamin D deficiency because breast milk contains insufficient amounts of vitamin D. Canadian health policy recommends all breastfed infants receive 400 IU/d of vitamin D starting at birth and continuing until infants can obtain this amount through diet. Both dietary and endogenous production of vitamin D are commonly measured using the 25-hydroxyvitamin D metabolite (25(OH)D), as it has a longer half-life and is less hormonally regulated than the active form, 1,25-dihydroxyvitamin D. The Institute of Medicine (IOM) defines the amount necessary to meet the needs of 97.5% of a population group as the Recommended Dietary Allowance (RDA), however due to insufficient supportive data for the 0-12 mo age group an Adequate Intake (AI) level of 400 IU/d was established instead. This amount is thought to maintain circulating 25(OH)D concentrations in the range of 40-50 nmol/L, sufficient for bone health. Others argue concentrations >75 nmol/L are necessary and that some infants and children may require 800 IU/d of vitamin D supplementation. Despite these recommendations, many infants in Canada have low circulating 25(OH)D concentrations. It is unclear whether these low concentrations are due to a lack of compliance or that the recommendations are insufficient to achieve the desired circulating 25(OH)D concentrations. In addition, whether intakes of vitamin D >400 IU/d in infancy are associated with better bone mineral accrual has not been systematically tested. There are two isoforms of vitamin D which are available as supplements in Canada, cholecalciferol (vitamin D3) and ergocalciferol (vitamin D2). Controversy exists regarding the biological effectiveness of both forms to increase 25(OH)D concentrations. Health Canada's 2004 recommendation states vitamin D2 is less effective than D3 for supplementation, yet no studies have directly compared the efficacy these isoforms in infants. The global objectives of this thesis are to: (1) describe vitamin D supplementation practices of mothers of newborns from a large Canadian urban center; (2) compare the biological response to supplemental vitamin D2 and D3 isoforms in breastfed infants from 1 to 4 mo of life; and (3) define the dosage requirement of vitamin D3 based on (a) the amount necessary to raise plasma 25(OH)D to ≥75 nmol/L in 97.5% of infants (as used in setting the RDA) and (b) using measures of mineral homeostasis, growth and bone mass. Study 1 consisted of a telephone survey with 342 mothers who delivered at the Royal Victoria Hospital (Montréal, Québec), representing ~10% of all annual births at this center. Mothers were contacted 6-12 mo post-partum and asked about vitamin D supplementation practices including the amount and frequency of dosage as well as reasons for non-adherence. Study 2 was a randomized clinical trial (RCT) of 52 breastfed infants. At 1 mo of age, infants received 400 IU/d of either vitamin D2 or D3 for 3 mo. The change in plasma 25(OH)D concentrations as well as the proportion of infants which achieved ≥50 and ≥75 nmol/L plasma 25(OH)D targets were compared between groups. Study 3 was a RCT in which 132 healthy, breastfed 1 mo old infants were randomly assigned to receive one of 4 vitamin D dosages (400, 800, 1200 or 1600 IU/d of vitamin D3).
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,006 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,001 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».