Maternal vit D study highlights need for supplementation

The study, published in Frontiers in Nutrition​, explored the association of maternal serum 25(OH)D levels with infant’s gut microbiota in Chinese mothers and offspring, and evaluated its potential influence on offspring’s gut microbiota from one to six months old.

“Our findings highlight that maternal vitamin D status plays a pivotal role in shaping the early-life gut microbiota of the next generation,” the authors concluded, adding that “due to the chronicity of vitamin D deficiency and the potential for physiologic adaptations to this condition”, a longer supplementation period might be necessary, possibly even commencing prior to pregnancy.

Maternal vitamin D

A growing body of evidence suggests that vitamin D during pregnancy is essential for optimal maternal and offspring health. Maternal vitamin D deficiency or insufficiency was considered as a significant risk factor for adverse maternal-fetal outcomes, including preeclampsia, gestational diabetes mellitus, low birth weight and preterm births.

Research into associations between maternal vitamin D supplementation during pregnancy and infant’s gut microbiota suggests vitamin D could impact the gut microbiota composition of offspring, but there have been few studies and a large heterogeneity of results.

The current study aimed to fill this gap in knowledge and evaluate the potential influence of maternal vitamin D status on the dynamic change patterns of offspring gut microbiota from one to six months old for the first time.

Study details

A total of 87 mother-infant dyads (vitamin D insufficient group vs. normal group = 59 vs. 28) were included in this longitudinal study. Basic characteristics of the subjects in the vitamin D insufficient group and the control group were similar and comparable, which reduced the confounding of related factors.

Two fecal samples were collected for the included infant at home by the parents at 1 month of age (“M1 phase”) and six months of age (“M6 phase”). Gut microbiota were profiled by 16S rRNA gene sequencing. We performed mixed effects models on alpha diversity metrics, PERMANOVA tests on beta diversity distances and linear discriminant analysis (LDA) to identify differently abundant taxa.

Resulting data indicated significantly lower Pielou’s evenness and Shannon diversity in the vitamin D insufficient group at six months but not at one month.

The dynamic changes in alpha diversity from one to six months old were significantly different according to maternal vitamin D status.

There were significant differences in gut microbiota composition between the vitamin D insufficient group and normal group, both at month one and six.

Moreover, among the predicted metagenome functions, pathways related to amino acid biosynthesis, starch degradation and purine nucleotides biosynthesis were enriched in the vitamin D insufficient group.

Limitations of the study included the small sample size and the unmeasured confounding factors such as maternal dietary habits, hygiene practices and medication.

The authors concluded: “maternal vitamin D levels during pregnancy, as a modifiable factor, is of great public health significance in the prevention of many diseases, such as allergic diseases, by influencing the maintenance of gut microbiota homeostasis. Therefore, vitamin D supplementation is strongly recommended in clinic practice.

"However, due to the chronicity of vitamin D deficiency and the potential for physiologic adaptations to this condition, a longer supplementation period might be necessary, possibly even commencing prior to pregnancy.”

Mechanisms of action

Discussing the potential mechanism of action behind vitamin D’s impact on the gut microbiota of infants, the report noted that Ooi et al.​ demonstrated that 1,25(OH)2D3 deficiency and vitamin D receptor knockout can affect the gut microbiome by increasing inflammation, and more gut inflammation provides a conducive environment for pathogens to proliferate at the expense of beneficial bacterial species.

Vitamin D may also affect the gut microbiome by upregulating innate immunity, producing antimicrobial peptides​ through macrophages, maintaining the gut barrier function and altering calcium and phosphate absorption.

Since an infant’s gut microbiota is inherited from the mother’s to some extent​, therefore, the researchers hypothesized that maternal vitamin D influenced maternal gut microbiota and was then provisioned to fetuses in utero​, which decided the first microbial colonizers of the infant’s gut.

However, mechanistic links between maternal vitamin D status and gut microbiome in offspring remain to be elucidated.

Frontiers in Nutrition​
doi: https://doi.org/10.3389/fnut.2024.1428356​
“Maternal vitamin D status during pregnancy and infant’s gut microbiota: a prospective cohort study”
Authors: Song Qiying et al.