ABSTRACT
BACKGROUND: Parents are advised to avoid the direct sun exposure of their newborns. Therefore, the vitamin D status of exclusively breastfed newborns is entirely dependent on the supply of vitamin D from breast milk. OBJECTIVES: We explored concentrations of ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3) (vitamin D) and 25-hydroxivitamin D2 plus D3 (25-hydroxyvitamin D [25(OH)D]) in foremilk and hindmilk during the first 9 mo of lactation and identified indexes of importance to the concentrations. DESIGN: We collected blood and breast-milk samples from mothers at 2 wk (n = 107), 4 mo, (n = 90), and 9 mo (n = 48) postpartum. Blood samples from infants were collected 4 and 9 mo after birth. We measured concentrations of vitamin D metabolites in blood and milk samples with the use of liquid chromatography-tandem mass spectrometry. RESULTS: Concentrations of vitamin D and 25(OH)D correlated significantly and were higher in hindmilk than in foremilk. Milk concentrations were also correlated with maternal plasma 25(OH)D concentrations. In foremilk and hindmilk, concentrations were a median (IQR) of 1.35% (1.04-1.84%) and 2.10% (1.63-2.65%), respectively, of maternal plasma 25(OH)D concentrations (P < 0.01). Milk concentrations showed a significant seasonal variation. Mothers who were taking vitamin D supplements had higher concentrations than did nonusers. Medians (IQRs) of infant daily intake through breast milk of vitamin D and 25(OH)D were 0.10 µg (0.02-0.40 µg) and 0.34 µg (0.24-0.47 µg), respectively, which were equal to a median (IQR) antirachitic activity of 77 IU/d (52-110 IU/d). CONCLUSIONS: The supply of vitamin D from breast milk is limited. Exclusively breastfed infants received <20% of the daily dose recommended by the Institute of Medicine for infants during the first year of life. This trial was registered at clinicaltrials.gov as NCT02548520.
Subject(s)
Breast Feeding , Infant Nutritional Physiological Phenomena , Lactation/metabolism , Maternal Nutritional Physiological Phenomena , Milk, Human/metabolism , Vitamin D Deficiency , Vitamin D/metabolism , Adult , Calcifediol/metabolism , Cholecalciferol/metabolism , Dietary Supplements , Energy Intake , Ergocalciferols/metabolism , Female , Follow-Up Studies , Humans , Infant , Infant, Newborn , Postpartum Period , Pregnancy , Vitamin D/analogs & derivatives , Vitamin D/blood , Vitamin D/therapeutic use , Vitamin D Deficiency/blood , Vitamin D Deficiency/etiology , Vitamin D Deficiency/prevention & control , Young AdultABSTRACT
BACKGROUND: The risk of type 1 diabetes (T1DM), infections, cancer, schizophrenia and multiple sclerosis (MS) has been associated with environmental factors including vitamin D status. MATERIALS AND METHODS: Data were obtained from all children born in Denmark in 1940 (n = 72,839), 1977 (n = 89,570), and 1996 (n = 74,015). Information on contacts to hospitals (1977-2009) was obtained from the National Hospital Discharge Register. The main exposure variable was season of birth as a proxy variable for vitamin D status (summer: April-September and winter: October-March). RESULTS: No associations between season of birth and risk of MS were seen in the 1940 cohort or the 1996 cohort. In the 1977 cohort, there was a borderline statistically significant decreased risk of MS in those born during wintertime compared with those born during summertime (HR = 0.70, 95% CI: 0.47-1.04, p = 0.07). There were no significant differences within the groups regarding season and risk of T1DM at any age, T1DM before 10 y, infection, any type of cancer, schizophrenia and myocardial infarction. In the 1977 cohort the risk of pneumonia was significantly lower among those born in the summer compared with the winter at any age (HR 0.91, 95% CI 0.85-0.97, p < 0.01) and at age < 10 y (HR 0.90, 95% CI 0.84-0.97, p < 0.01). CONCLUSION: MS and pneumonia in young subjects may be related to season of birth and thus maternal vitamin D exposure. Low sunlight exposure in the winter time leading to low vitamin D levels during pregnancy may be a potential explanation.
