Changes in breast milk composition for women with COVID-19

Researchers from the University of Huelva, in collaboration with Spain’s MilkCORONA initiative, have confirmed that infection by the SARS-CoV-2 virus modifies the supply of nutrients to infants via breast milk. Although the alterations caused by the disease in human serum and blood are already known, this is the first study that analyses the elements that vary in the food of newborns, and opens the door to new studies on the possible benefits of including supplements in the diets of lactating women.

Metabolomic studies consist of the analysis of chemical reactions that occur in the organism; that is, how different compounds behave in the course of functional and structural processes in biofluids, organs, tissues and cells. In addition, they establish relationships between the alterations that may occur with the appearance of other agents or substances that are incorporated in the different phases. Thus, when a virus acts, chemical reactions in the organism change against the threat.

In relation to SARS-CoV-2, previous research has confirmed the metabolomic modifications that occur in serum and blood, as well as alterations in the chemical elements profile. Experts now present the results of the first study using breast milk, as published in the journal Molecular Nutrition & Food Research.

By describing the metabolomic profile and element levels in breast milk samples of COVID-19 patients and comparing them with pre-pandemic controls, the study demonstrates that SARS-CoV-2 affects the composition of nutrients reaching the baby, which is related to the body’s defences against the disease. In addition, the study also analyses the impact of virus symptomatology at different stages of breastfeeding and the associations between COVID-19 antibodies and chemical elements in human milk.

Some of the conclusions of this study confirm the data obtained in previous studies with blood, such as those concerning the decrease in selenium or cobalt levels due to the disease. For other elements, such as zinc or copper, the concentrations detected run counter to the results obtained with blood or serum.

“In the case of zinc, the amounts in people with COVID-19 are lower in blood, but higher in human milk compared to healthy women,” said study co-author Tamara García-Barrera. “It is possible that this happens because a higher intake of this element is required in the bloodstream to cope with the virus, but its levels are not reduced in breast secretion.”

Zinc deficiency has been linked to complications during the disease. In some cases, zinc supplementation has been effective in treating acute cases of COVID-19. Therefore, the higher levels of zinc found in breast milk may be due to the fact that it is beneficial for the newborn.

The samples analysed in this study come from a total of 54 people. Among them, 20 were from healthy women before the pandemic, 18 from sick women with symptoms and 16 from asymptomatic sick women. The results show no significant differences in these last two groups as regards the composition of elements, but there were significant differences in metabolites. In addition, differences have been observed in relation to control samples in both cases.

The elements that were detected at lower concentrations in human milk were selenium, nickel, iron, copper, vanadium and aluminium, while those of zinc, titanium or arsenic were higher. In previous studies, increased blood copper levels have been linked to the inflammation that occurs in the airways during the disease. Low selenium has been associated with increased mortality from COVID-19.

“Knowing the importance of this element for the neurological development of the baby, the knowledge that the disease reduces its concentration in milk may suggest the need to supplement the diet of mothers affected by this virus to increase the amounts they transfer to the newborn,” García-Barrera said.

The study also links certain elements to COVID-19 antibodies. Although the possibility of infection during breastfeeding and the transmission of antibodies to the baby has been studied, the experts now insist on the relationship between certain elements and the body’s defences. Thus, they have confirmed that the higher the antibody index, the lower the concentration of selenium, nickel and cobalt, while the amounts of copper are higher. The results also conclude that a total of nine metabolites — including uric acid, a powerful antioxidant, and cholesterol, which is necessary for hormone formation — were found to be low in sick mothers. 11 others, such as phosphoric acid, which is responsible for pH regulation, were regulated upwards in sick women.

The experts propose to continue these studies, taking into account the diet of the mothers and the possible impact of vaccines on milk.

Image credit: iStock.com/Anastasiia Stiahailo

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