Writing in the American Journal of Clinical Nutrition, scientists from the University of Helsinki and the Finnish Institute for Health and Welfare reported that foods such as oats, rye, wheat, potatoes and berries were associated with bacterial diversity, emphasizing the importance of a healthy diet in the first year of life.
“Our data suggests that introducing fiber-rich, plant-based foods support the early life microbiota during weaning,” they wrote.
The findings add longitudinal evidence to previously described bacterial patterns in the maturing gut, expanding the benefits of weaning within four to six months to support future health and help prevent allergies.
“Notably, novel fiber sources of oats, fruits, vegetables and potatoes, commonly found in first spoon-fed purees, showed associations to infant type bacterial species from genera Bifidobacterium, Bacteroides, Lactobacillus, Streptococcus, Enteroccoccus and Veillonella with key roles in immunomodulation,” the researchers wrote.
The study noted that, in contrast, other studies have found that high-sugar infant cereals lead to lower bacterial diversity despite having identical fiber content to low-sugar versions.
“Although breastfeeding remains the nutritional gold standard, these findings emphasize the importance of considering the impacts of first food choices on gut microbiome composition and maturation,” the researchers added.
The maturing infant gut
After birth, microbes colonize the newborn’s sterile gut, and the microbiome continues to evolve dynamically until stable communities are established at around three years of age.
Several factors influence the process of establishing infants’ gut bacteria, including the mother’s health and microbiome, the delivery method, breastfeeding, antibiotic usage and the introduction of solid foods.
The critical window for intestinal bacterial colonization affects infants’ immune system development and may predict obesity, allergic diseases and inflammation in childhood and later life.
While human milk oligosaccharides (HMOs) in breast milk jump start the infant’s microbiome and immune system, the inclusion of dietary fibers while weaning onto solid foods expands the bacterial diversity in the gut.
“More mature gut microbiome communities appeared around 9 mo when complementary food fiber intake (7.7 g/d) surpassed HMO intake (6.4 g/d) in infants who were partially breastfed,” the current study reported.
It also noted that while protein and fiber are both introduced during weaning, high-fiber foods can produce more favorable metabolites that enhance the gut barrier, prevent inflammation and enhance insulin sensitivity.
Study details
Using data from the Early Dietary Intervention and Later Signs of β-Cell Autoimmunity (EDIA) cohort in Tampere, Finland, which followed 73 pregnant females and their newborn infants from the third trimester of pregnancy until the infant was one year old, the researchers analyzed stool samples and the gut microbiome in relation to total dietary fiber (TDF) from food intake records.
This generated 176 plant-based complementary food fiber-bacterial species associations, of which 84% were positive for the maturation of the infant’s gut.
“Oats, rye, wheat and potatoes were associated with 16, 14, 16 and 15 mostly unique bacterial species, respectively,” the researchers wrote, noting that even a daily spoonful of mixed berries had a notable impact evidenced by 14 distinct bacterial associations.
“In turn, human milk with its fiber associated with lower species diversity, inversely associating with genera and species common in late infancy, suggesting that they control the maturation rate, as previously described.”
Breastfeeding was the most significant factor shaping the gut microbiome in early infancy, followed by infant age. Fiber intake from complementary foods at month 12 was associated with the overall bacterial composition, but no other food-related variable showed a significant association.
The study noted that experts recommend introducing allergenic foods such as nuts and eggs within the four- to six-month window, and complementary food fibers could potentially help reduce sensitization. They called for further research to investigate the role of the diet-gut microbe axis.
Source: The American Journal of Clinical Nutrition,
Published online ahead of print, doi: 10.1016/j.ajcnut.2024.11.011
“Associations between dietary fibers and gut microbiome composition in the EDIA longitudinal infant cohort.”
Authors: M. K. Lalli et al.
