Quantification and reporting of vitamin D concentrations measured in human milk by LC-MS/MS.
Frontiers in nutrition 2023 ; 10: 1229445.
Jones KS, Meadows SR, Koulman A
DOI : 10.3389/fnut.2023.1229445
PubMed ID : 38035362
PMCID : PMC10687194
URL : https://www.frontiersin.org/articles/10.3389/fnut.2023.1229445/full
Abstract
Vitamin D is essential for optimal bone health, and vitamin D deficiency has been associated with an increased risk of adverse pregnancy, growth and developmental outcomes. In early life, and in the absence of endogenous vitamin D production from UVB light, infants are reliant on vitamin D stores established and the vitamin D supply from human milk (HM). However, comprehensive data on vitamin D in HM is lacking. Thus, in this review we explore the application of liquid-chromatography tandem mass spectrometry (LC-MS/MS) to the assessment of vitamin D in HM. We discuss the challenges of extracting and measuring multiple vitamin D metabolites from HM including the frequent requirement for a large sample volume, and inappropriate poor sensitivity. Shortcomings in the reporting of experimental procedures and data analysis further hinder advances in the field. Data collated from all studies that have applied LC-MS/MS reveal that, in general, cholecalciferol concentration is greater and more variable than 25-hydroxyvitamin D concentration, and that the vitamin D content of HM is low and less than the currently recommended dietary requirement of infants, although maternal supplementation can increase the vitamin D content of HM. Improvements in analytical methods and their validation and larger, more representative studies are required to better characterize HM milk vitamin D metabolite concentrations and their relationship with maternal status. These data are essential to understand relationships with infant health and to inform public health policies around vitamin D fortification and supplementation.
Lay Summary
The World Health Organisation (WHO) recommends that babies under six months of age are fed only human breast milk. However, there is limited information on the micronutrient content of human milk, and it is largely unknown what healthy levels of vitamins are in human milk and how they relate to vitamin levels in mothers and babies. Vitamin D is essential for normal bone growth and development so it is important to understand how much vitamin D babies receive through human milk. However, measuring vitamin D in milk is challenging. Liquid chromatography coupled with tandem mass spectrometry is a specialist and powerful analytical tool, ideal for separating and measuring levels of vitamin D in human milk.
In this paper, we bring together methods and results from studies that have used mass spectrometry to measure vitamin D in human milk. We found that published methods can have shortcomings, for example, they may require a large volume of milk for analysis, may not be sensitive enough to measure low vitamin D levels, or may not measure the different forms of vitamin D found in human milk. The results from the studies suggest that the concentration of vitamin D in human milk is too low to achieve recommended intake levels, but can be increased through maternal dietary vitamin D supplementation or exposure to sunlight. We conclude that better methods are required to measure vitamin D levels in human milk and that this will allow larger studies with more women and infants. This in turn will provide a better understanding of the vitamin D content of human milk to better inform public health policies around vitamin D fortification and supplementation.