Probiotics and iron bioavailability: mechanisms, clinical evidence, and translational applications-a comprehensive review of the probiotic strain Lactiplantibacillus plantarum 299v (LP299V®).

Iron deficiency remains the most prevalent micronutrient deficiency globally, driven in large part by the limited bioavailability of non-heme iron and compounded by dietary inhibitors, inflammation-mediated hepcidin regulation, and challenges associated with conventional iron supplementation. Health effects of prolonged iron deficiency include heart irregularities, weakened immunity, and cognitive impairment. Growing evidence highlights the gut microbiome as a key modulator of nutrient absorption, with probiotics emerging as a promising adjunctive strategy. Among these, the Lactiplantibacillus plantarum strain Lp299v (LP299V®, proprietary strain of Probi®) has demonstrated consistent efficacy in enhancing non-heme iron bioavailability through multiple complementary mechanisms, including luminal acidification via organic acid production, stabilization and chelation of soluble iron complexes, facilitation of ferric-to-ferrous reduction, and potential mitigation of inhibitors such as phytates. Additional effects on host physiology, such as improved intestinal barrier function, increased short-chain fatty acid production, and attenuation of inflammation, further support its role in optimizing iron uptake. The present review gives an overview of how probiotic strains may modulate iron absorption, and more specifically focuses on describing effects obtained with the Lp299v strain. Ten peer-reviewed clinical studies have described the effects of Lp299v for increasing iron absorption. Human isotope studies show that Lp299v increases fractional iron absorption by approximately 20-50% across diverse dietary contexts, while randomized controlled trials and meta-analyses indicate meaningful improvements in iron status, particularly in populations with elevated requirements such as women of reproductive age, pregnant women, and athletes. From the mechanistic studies combined with clinical evidence, results suggest that Lp299v functions as a bioavailability enhancer rather than a substitute for iron intake. Given its versatility in delivery formats, favorable safety profile, and applicability across a range of dietary patterns and socioeconomic settings, Lp299v represents a microbiome-informed approach to addressing the persistent global burden of iron deficiency that has great potential for widespread adoption. This review aims to describe the gut microbiome as an important determinant of micronutrient bioavailability, and, more specifically, to summarize the data supporting Lp299v as a key modulator of iron absorption.