Probiotic Supplementation and Micronutrient Status in Healthy Subjects: A Systematic Review of Clinical Trials

Study answer

What this study found

Probiotic intake in healthy subjects may improve micronutrient status, notably vitamin B12 and folate, calcium, zinc and iron. Two of three folate/B12 trials reported improvements; calcium status improved in multiple pediatric and postmenopausal studies; zinc status improved in some trials, particularly with zinc co-supplementation; iron status improvements were variable, with some ferritin and Hb changes and evidence for increased non‑heme iron absorption with certain Lactobacillus strains; vitamin D status improved in some cases (e.g., L. reuteri NCIMB30242 and multi-strain regimens in…

Study & population

Healthy humans across age groups including children and adults; sexes mixed; some subgroups included iron-deficient athletes and vegan subjects; study designs included randomized double-blind placebo-controlled trials, cross-over trials, open-label randomized multicenter trials, randomized trials without blinding, and non-randomized trials.

Intervention

Regimens varied across 14 trials: probiotic or synbiotic supplements delivered via yogurt/fermented milk, fortified beverages, capsules or tablets, or powders; single- and multi-strain products used.

Key limitation

High heterogeneity across studies (age, strains, doses, durations, administration form) and predominantly moderate-to-high risk of bias; only one study had low risk of bias; several trials nonrandomized or lacking blinding; small to moderate sample sizes; limited dietary control; many studies conducted in Europe;…

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Original abstract