This is an update of my 2016 post: Low Iron – A Gut Bacteria Connection. One key addition is that Vitamin A supplementation may have significant positive impact.

The microbiota shifts the iron sensing of intestinal cells [2016]. “The amount of iron in the diet directly influences the composition of the microbiota. Inversely, the effects of the microbiota on iron homeostasis have been little studied….Commensal organisms (Bacteroides thetaiotaomicron VPI-5482 and Faecalibacterium prausnitzii A2-165) and a probiotic strain (Streptococcus thermophilus LMD-9) led to up to 12-fold induction of ferritin in colon.”

Probiotics to Take

• Probiotic strain Lactobacillus plantarum 299v increases iron absorption from an iron-supplemented fruit drink: a double-isotope cross-over single-blind study in women of reproductive age[ 2015 ].[2017] [2019] [2020] [2021]
• Effects of Lactobacillus casei on Iron Metabolism and Intestinal Microflora in Rats Exposed to Alcohol and Iron.[2022]
• “No significant differences were found between the two yogurts (one with live  cultures and the other without) in terms of their effects on serum iron, AST and ALT levels.” [2013] – so only certain  bacteria are involved. Most lactobacillus do not have an effect [2007]
• Oral administration of Bifidobacterium longum CECT 7347 ameliorates gliadin-induced alterations in liver iron mobilisation [2013].
• “we show that a panel of probiotics are not able to respond to increased iron availability, and identify an isolate of Streptococcus thermophilus NCIMB 41856 that can increase growth rate in response to increased iron availability.” [2011]
• Vitamin A modulates the expression of genes involved in iron bioavailability [2012] [2019]
• Heat-Killed Lactococcus lactis subsp. cremoris H61 Altered the Iron Status of Young Women: A Randomized, Double-Blinded, Placebo-Controlled, Parallel-Group Comparative Study [2022]

Likely No or Negative Effect

• “Bifidobacterium bifidum.. decreased amounts of calcium and iron released from bread.” [2012]
• Probiotics Lactobacillus reuteri DSM 17938 and Lactobacillus casei CRL 431 modestly increase growth, but not iron and zinc status, among Indonesian children aged 1-6 years [2013].
• “we show that a panel of probiotics are not able to respond to increased iron availability, and identify an isolate of Streptococcus thermophilus NCIMB 41856 that can increase growth rate in response to increased iron availability.” [2011]
• Probiotic bacteria reduce salmonella typhimurium intestinal colonization by competing for iron [2013]. “Thus, iron availability impacts S. Typhimurium growth, and E. coli Nissle reduces S. Typhimurium intestinal colonization by competing for this limiting nutrient.” – So E.Coli probiotics and iron deficiency may not play well together.
  • ” Intestinal bacteria compete for the essential nutrient iron, leading to replacement of pathogenic Salmonella by the probiotic Escherichia coli Nissle, which is better equipped with iron acquisition systems, and resolution of infectious colitis.” [2013]