Selenium in Pregnancy May Lower Risk of Streptococcal Infections in Children, Study Finds

A large-scale study from Japan suggests that higher selenium levels in pregnant women may help protect their children from streptococcal infections during early childhood.

A mother’s nutrition during pregnancy may play a powerful role in shaping her child’s immune defenses, new research suggests.

It’s a mineral you’ve probably heard of but rarely think about. Found in fish, eggs, and Brazil nuts, selenium quietly supports your immune system and overall health. Now, researchers believe it could play a role in shielding young children from a common bacterial infection.

A Nationwide Study with Global Implications

Researchers from Hokkaido University have uncovered a surprising link between maternal nutrition and childhood health. Using data from over 74,000 mothers and their children enrolled in the Japan Environment and Children’s Study (JECS), scientists examined how exposure to various metals and trace elements during pregnancy influenced the risk of streptococcal infections in early childhood. The findings of the study were published in PLOS ONE.

Blood samples were collected from expectant mothers during the second or third trimester to measure levels of selenium, mercury, lead, cadmium, and manganese. When the children were between three and four years old, any reported pediatric streptococcal infections were recorded based on physician diagnoses.

Foods rich in selenium include fish, nuts, meat, and grains.

The team found that children whose mothers had higher selenium levels were significantly less likely to develop streptococcal infections, including illnesses caused by Group A Streptococcus, such as strep throat and skin infections.

The Power of Selenium on the Immune System

Selenium is a trace element known for its crucial role in maintaining a healthy immune system. It helps regulate inflammation, supports antioxidant activity, and influences the function of immune cells.

“We found that mothers with higher selenium levels during pregnancy were less likely to have children who developed streptococcal infections,” said lead author Dr. Hiroyoshi Iwata of the Center for Environmental and Health Sciences at Hokkaido University.

In this study, mothers with selenium levels in the highest range (above the third quartile) had children with the lowest risk of strep infections, suggesting a dose-dependent protective effect.

Dr. Iwata noted that while the findings are promising, they come with a caveat. He explained that high concentrations of selenium during pregnancy could be toxic and cause harmful effects, so it must be used with discretion.

What This Means for Future Health Strategies

While the study does not suggest selenium supplements for all pregnancies, it opens the door for further research on how micronutrient levels in pregnancy influence childhood immunity. The researchers emphasized that only one blood sample was analyzed per participant, and the results should be interpreted with caution.

Still, this is one of the first large-scale studies to explore the connection between prenatal exposure to trace elements and childhood infections. It highlights how maternal health can shape a child’s resilience to disease in ways we’re just beginning to understand.

As scientists continue to uncover the links between diet, environment, and long-term health, one thing is clear: even the smallest nutrients can have a lasting impact.

News references:

Hokkaido University. "Selenium exposure during pregnancy may reduce childhood streptococcal infections." ScienceDaily. ScienceDaily, 20 May 2025. <www.sciencedaily.com/releases/2025/05/250520122241.htm>.

Iwata H, Ikeda A, Itoh M, Ketema RM, Tamura N, et al. (2025) Association between prenatal exposure to maternal metal and trace elements and Streptococcus infection: A prospective birth cohort in the Japan Environment and Children’s Study. PLOS ONE 20(2): e0319356. https://doi.org/10.1371/journal.pone.0319356

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