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Vitamin D metabolites in human milk
The Journal of Pediatrics
|May 1, 1982
Summary
Human milk contains low levels of vitamin D metabolites, including 25-hydroxyvitamin D (25-OHD), 24,25-dihydroxyvitamin D [24,25(OH)2D], and 1,25-dihydroxyvitamin D [1,25(OH)2D]. These levels do not correlate with maternal vitamin D status.
Area of Science:
- Nutritional biochemistry
- Endocrinology
- Human milk analysis
Background:
- Vitamin D metabolites are crucial for calcium homeostasis and bone health.
- Human milk is a primary source of nutrition for infants, but its vitamin D content is generally considered low.
- Understanding the specific forms and concentrations of vitamin D metabolites in human milk is important for infant nutrition.
Purpose of the Study:
- To quantify the concentrations of key unconjugated vitamin D metabolites in human milk.
- To investigate the relationship between vitamin D metabolite levels in human milk and maternal serum levels.
- To correlate metabolite concentrations with the known bioassayable vitamin D activity in human milk.
Main Methods:
- Competitive protein-binding radioassays were used to measure unconjugated 25-hydroxyvitamin D (25-OHD), 24,25-dihydroxyvitamin D [24,25(OH)2D], and 1,25-dihydroxyvitamin D [1,25(OH)2D].
- Preparative Sephadex LH-20 chromatography and High-Performance Liquid Chromatography (HPLC) were employed for metabolite separation and purification.
- HPLC with UV detection at 254 nm was specifically used to determine 25-OHD3 concentration.
Main Results:
- Mean concentrations were: 25-OHD (0.37 +/- 0.03 ng/ml), 24,25(OH)2D (24.8 +/- 1.9 pg/ml), and 1,25(OH)2D (2.2 +/- 0.1 pg/ml).
- The concentration of 25-OHD3 measured by HPLC was 0.27 +/- 0.08 ng/ml.
- No significant correlation was found between milk vitamin D metabolite concentrations and maternal serum 25-OHD levels.
- The total measured unconjugated vitamin D metabolites align with the established low antirachitic activity of human milk.
Conclusions:
- Human milk contains measurable, albeit low, concentrations of key unconjugated vitamin D metabolites.
- Maternal serum vitamin D status does not appear to directly influence the concentration of these metabolites in human milk.
- The findings support the understanding of human milk's limited contribution to vitamin D intake for infants.
- Further research may explore factors influencing vitamin D metabolite transfer into human milk.
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