Benefits
Increased non-heme iron absorption
Vonderheid 2019 meta-analysis of 8 RCTs (N=950) showed pooled standardized mean difference of 0.55 (95% CI 0.22-0.88, p=0.001) for iron absorption with Lp299v. Absorption from a meal increased from 20.9% (control) to 24.5% (with Lp299v) — a relative increase of ~17% (Hoppe 2017).
Improved iron status in iron-deficient athletes
Axling 2020 (n=39 completed, 12 weeks) — female non-anemic athletes with low iron stores (ferritin <30 μg/L). Lp299v + 20 mg iron produced more substantial and rapid ferritin increase than 20 mg iron alone. Particularly beneficial in low-baseline-ferritin subgroup.
Pregnancy iron status
Hoekstra 2021 (n=326 pregnant Swedish women) showed Lp299v with low-dose iron (4.2 mg), folic acid, and vitamin C from week 10-12 produced smaller decreases in serum ferritin at weeks 28 (p=0.003) and 35 (p<0.001) vs placebo. Reduced iron deficiency from 78% to 59% (p=0.017) and iron deficiency anemia from 21% to 7.4% (p=0.023).
IBS symptom relief
Multiple RCTs (Niedzielin 2001, Niv 2005, Ducrotté 2012) of Lp299v in irritable bowel syndrome show modest improvements in abdominal pain, bloating, and stool consistency. The strain's primary mechanism in IBS appears to involve mucin production, gut barrier function, and reducing pathogen adhesion.
Mechanism of action
Ferric iron stabilization in gut lumen
Lp299v has been shown to increase the amount of ferric iron (Fe³⁺) in in vitro digested meals and drinks. Combined with lower gut pH from lactic and acetic acid production, this creates more favorable conditions for iron solubilization and absorption — particularly important for plant-source iron in vegetarian/vegan diets.
Lactic and acetic acid production
Lp299v ferments dietary carbohydrates to lactic and acetic acid, lowering local pH. This both enhances iron solubility and inhibits pathogenic bacteria. The acid production may also activate phytases and reduce phytate-iron complexes that normally limit non-heme iron bioavailability.
Gut epithelial barrier and mucin support
Lp299v increases mucin (MUC2, MUC3) gene expression in gut epithelial cells, supporting the protective mucus barrier. This is one mechanism for the strain's IBS benefits and for reducing pathogen adhesion. Also implicated in athlete performance studies showing reduced GI distress.
Clinical trials
Systematic review and meta-analysis (Vonderheid, Tussing-Humphreys, Park, Pauls, Hemphill, LaBomascus, McLeod, Koenig 2019, Nutrients 11(12):2938).
8 trials examining Lp299v iron absorption effect (15 total studies on probiotics and iron, N=950 across all studies). Random-effects meta-analysis on the Lp299v subset.
Pooled standardized mean difference of 0.55 (95% CI 0.22-0.88, p=0.001) demonstrating significant iron absorption increase with Lp299v. Of all probiotic strains examined, only Lp299v consistently showed iron absorption benefit. Authors concluded Lp299v is the only probiotic with sufficient evidence to recommend for iron absorption support.
Randomized, double-blind, placebo-controlled, parallel study (Axling, Önning, Combs, Bogale, Högström, Svensson 2020, Nutrients 12(5):1279).
53 healthy non-anemic female athletes with low iron stores (ferritin <30 μg/L), 39 completed. Randomized to 10¹⁰ CFU Lp299v + 20 mg iron OR 20 mg iron alone, daily for 12 weeks.
Lp299v + iron group showed greater and more rapid ferritin increases than iron alone. Effect was particularly pronounced in subjects with baseline ferritin <20 μg/L. Mood state and physical performance markers also showed improvements. Established that Lp299v can reduce required iron supplement dosing while improving iron status.
Single-blind crossover trial using double isotope (⁵⁵Fe and ⁵⁹Fe) technique (Hoppe, Önning, Berggren, Hulthén 2015, Br J Nutr 114(8):1195-1202).
Healthy women of reproductive age. Trial 1: 10⁹ CFU Lp299v vs control fruit drink. Trial 2: 10¹⁰ CFU Lp299v vs control. ~5 mg iron as ferrous lactate per drink.
Both 10⁹ and 10¹⁰ CFU doses of Lp299v significantly enhanced non-heme iron absorption from a fortified fruit drink compared to the same drink without Lp299v. Established the dose range for the benefit and demonstrated efficacy with both viable doses.
Randomized, double-blind, placebo-controlled study (Axling, Hoekstra, Önning et al 2021, J Intern Med 290(5):1027-1041).
326 healthy non-anemic pregnant Swedish women. Randomized to Lp299v (10¹⁰ CFU) + 4.2 mg iron + 12 mg ascorbic acid + 30 μg folic acid OR placebo, twice daily from gestational week 10-12 until end of pregnancy.
Lp299v group showed significantly smaller ferritin decreases at week 28 (p=0.003) and week 35 (p<0.001). Iron deficiency prevalence reduced from 78% to 59% (p=0.017). Iron deficiency anemia reduced from 21% to 7.4% (p=0.023) at week 35. Demonstrated clinically important benefits with low-dose iron — addressing the GI tolerance issues of standard pregnancy iron supplementation.
About this ingredient
Lactiplantibacillus plantarum 299v (originally classified as Lactobacillus plantarum 299v, reclassified in 2020) is the proprietary probiotic strain DSM 9843, developed and patented by Swedish probiotics company Probi AB. Originally isolated from sourdough, the strain has been in commercial use since the 1990s, sold under the LP299V® trademark and used in fortified products like TipTop fruit drink and ProViva. The strain produces lactic and acetic acid, expresses mannose-specific adhesion sites that may displace pathogens, and uniquely affects iron absorption.
Recommended dose 10⁹–10¹⁰ CFU/day. EVIDENCE: One of the most clinically validated single probiotic strains, with 50+ human RCTs across iron absorption, IBS, postoperative recovery, pediatric infection prevention, and immune support. The Vonderheid 2019 meta-analysis is particularly strong for iron absorption — Lp299v stood out from 14 other probiotic strains evaluated.
Pivotal trials include Axling 2020 (athletes), Hoekstra 2021 (pregnancy), Hoppe 2015/2017 (mechanism), and Niv 2005/Ducrotté 2012 (IBS). 4/5 evidence rating reflects the strong iron absorption evidence; IBS evidence is more modest. SAFETY: Excellent safety record over 30+ years of commercial use.
Awarded QPS (Qualified Presumption of Safety) status by EFSA. Suitable for pregnancy (Hoekstra 2021), pediatric use (multiple infant studies), and elderly populations. Main practical caveats: separate from antibiotics, store properly to maintain viability, and ensure CFU count meets the 10⁹–10¹⁰ minimum at end of shelf life.