A systematic review of contaminants in donor human milk

Abstract

Donor human milk (DHM) from a milk bank is the recommended feeding method for preterm infants when the mother's own milk (MOM) is not available. Despite this recommendation, information on the possible contamination of donor human milk and its impact on infant health outcomes is poorly characterised. The aim of this systematic review is to assess contaminants present in DHM samples that preterm and critically ill infants consume. The data sources used include PubMed, EMBASE, CINAHL and Web of Science. A search of the data sources targeting DHM and its potential contaminants yielded 426 publications. Two reviewers (S. T. and D. L.) conducted title/abstract screening through Covidence software, and predetermined inclusion/exclusion criteria yielded 26 manuscripts. Contaminant types (bacterial, chemical, fungal, viral) and study details (e.g., type of bacteria identified, study setting) were extracted from each included study during full-text review. Primary contaminants in donor human milk included bacterial species and environmental pollutants. We found that bacterial contaminants were identified in 100% of the papers in which bacterial contamination was sought (16 papers) and 61.5% of the full data set (26 papers), with the most frequently identified genera being Staphylococcus (e.g., Staphylococcus aureus and coagulase-negative Staphylococcus) and Bacillus (e.g., Bacillus cereus). Chemical pollutants were discovered in 100% of the papers in which chemical contamination was sought (eight papers) and 30.8% of the full data set (26 papers). The most frequently identified chemical pollutants included perfluoroalkyl substances (six papers), toxic metal (one paper) and caffeine (one paper). Viral and fungal contamination were identified in one paper each. Our results highlight the importance of establishing standardisation in assessing DHM contamination and future studies are needed to clarify the impact of DHM contaminants on health outcomes.

Keywords: breast milk; contaminants; donor milk.

Figure 1

PRISMA diagram. A literature search of PubMed, EMBASE, CINAHL and Web of Science (WoS) resulted in 372 papers. Fifty‐four papers were extracted from the references of the publications retrieved through our initial search. There were 130 papers from PubMed/MEDLINE, 91 papers from CINAHL, 78 papers from Embase and 73 papers from WoS. Two hundred and seventy‐eight papers were screened for eligibility after duplicates were removed through Covidence. One hundred and fifteen studies were initially excluded during title and abstract screening for irrelevance. One hundred and sixty‐three studies were assessed through a full‐text review and 141 were removed for wrong outcomes (100), systematic/scoping review (19), extensive focus on pasteurisation (10), wrong patient population (3), opinion (2), case study (1) and focus on nutrients in DHM (6). Four papers were added via expert recommendation to yield 26 papers in our data set. The graphic above characterises the search and selection process.

Figure 2

Contaminants found in donor human milk. Note: All 26 papers identified contaminants in donor milk. Bacterial contaminants were identified in 16 of the 26 papers. Chemical contaminants were identified in six papers. Viral contaminants were identified in one paper and fungal contaminants were also identified in one paper.