How prebiotics could help fight iron deficiency in infants

Iron deficiency is one of the most common nutritional challenges in early life, affecting 40% of children under five globally and leading to potential developmental challenges. However, solving this issue isn’t as simple as adding more iron. The body tightly regulates its iron uptake, and unabsorbed iron that passes to the colon can disrupt the gut microbiome.

Babies are born with iron stores from their mothers’ blood, which generally last the first 4–6 months of life. After this, the infant must rely on dietary intake of iron.

In regions where diets are often iron-poor, such as parts of Africa, Asia, and the Middle East, this creates a conundrum: how do you prevent infant iron deficiency without increasing the risks that come with higher iron loads? 

Danone R&I researchers set out to solve these challenges by investigating whether affordable prebiotic fibers could enhance iron bioavailability, helping the body absorb more of the iron already present in infant milk formula.

In a new research paper published in the Journal of Agricultural and Food Chemistry, Gabriel Thomassen and a team of researchers at Danone R&I used combined gastrointestinal digestion models, fermentation with infant fecal microbiota, and human intestinal cell cultures to track how prebiotic fibers behave from the small intestine through to the colon, and how they influence iron bioavailability.

Different prebiotic formulations were tested, including inulin, long-chain fructooligosaccharides (lcFOS), and combinations of both. These were compared to a reference prebiotic mixture of lcFOS and short chain galacto-oligosaccharides (scGOS) commonly used in infant nutrition, which has been previously shown to increase iron absorption and reduce the gut microbiome disruption caused by iron supplementation. However, scGOS lower affordability limits practical applications across the regions with the highest rates of infant iron deficiency.

The study found that combining inulin and lcFOS increased overall iron bioavailability by approximately 1.5× overall across the model digestive system, approaching the effect of the less affordable established scGOS:lcFOS mixture.

These effects differed across the digestive tract. In the small intestine model, the 1:1 and 2:1 inulin:lcFOS combinations produced a modest but statistically significant 1.2-fold increase in iron bioavailability compared to the control. In contrast, inulin:lcFOS fermentation increased colonic iron bioavailability by 3.4 to 3.7-fold, compared to 5-fold for scGOS:lcFOS

The inulin:lcFOS combinations were also associated with changes in the gut microbiome. Both inulin:lcFOS and scGOS:lcFOS supported a beneficial modulation of the gut microbiota; however, the magnitude of the bifidogenic effect was greater for scGOS:lcFOS .

The scientists observed a strong correlation between acetic acid (produced during prebiotics fermentation) and iron bioavailability. This suggests that microbial metabolites may help maintain iron in a soluble form that is more readily available for absorption. 

These findings suggest that a widely available, lower-cost prebiotic blend could achieve comparable iron bioavailability benefits to more expensive formulations – supporting the development of accessible infant milk solutions for populations most at risk.

For infants, this is particularly important. After birth, iron stores typically last four to six months, after which dietary intake becomes critical. Infants in regions with a high prevalence of iron-deficiency, where the body's iron absorption mechanisms are already upregulated, may be especially responsive to bioavailability-enhancing interventions.  

More broadly, the scientists’ findings demonstrate the importance of considering not only how much of a nutrient is supplemented, but also how effectively the body can use it, as well as how improving the gut microbiome environment can itself become a lever for better nutrient absorption. 

This research reflects the kind of science at Danone R&I that can translate into meaningful, accessible improvements in early-life health for millions of children worldwide. 

These findings are based on laboratory models and require validation in clinical studies in infants. Future research will focus on confirming whether these prebiotic combinations improve iron status in infants, and how the inulin:lcFOS blend could represent a practical, cost-effective route to improving iron status in populations where deficiency remains a significant public health challenge.

1. Gabriel G. M. Thomassen, Fernanda Olguin-Diaz, Ioannis Kostopoulos, Katherine Preece, Harm Wopereis, Marion Jourdan, Jan Knol, Evan Abrahamse, and Ingrid B. Renes. Journal of Agricultural and Food Chemistry 2026 74 (11), 9294-9306 DOI: 10.1021/acs.jafc.5c13296

2. Indrio F, Dargenio VN, Marchese F, Giardino I, Vural M, Carrasco-Sanz A, Pietrobelli A, Pettoello-Mantovani M. The Importance of Strengthening Mother and Child Health Services during the First 1000 Days of Life: The Foundation of Optimum Health, Growth and Development. J Pediatr. 2022 Jun;245:254-256.e0. doi: 10.1016/j.jpeds.2022.03.001.

3. Husmann FMD, Zimmermann MB, Herter-Aeberli I. The Effect of Prebiotics on Human Iron Absorption: A Review. Adv Nutr. 2022 Dec 22;13(6):2296-2304. doi: 10.1093/advances/nmac079.