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Head-to-head evidence comparison — which supplement is right for you?
Iron vs L. rhamnosus GG: Iron has the stronger overall evidence (9 vs 6/10); they're alternatives for support immune system — the best pick depends on your goals. Take the 60-second quiz for a pick tailored to your goals.
Iron wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
6 of 8 studies with measurable effects showed benefit.
Top outcomes
Verdict
Mostly mechanism / observational
Top outcomes
18-40mg elemental iron for deficiency (varies by severity) (a typical label dose, not the dose used in the cited trials, which used 60 to 120 mg a day)
On empty stomach if tolerated, Away from tea, coffee, dairy
Ferrous bisglycinate (gentle, well-absorbed) or iron protein succinylate
10-20 billion CFU (1-2 x 10^10) daily. A meta-analysis in children with acute gastroenteritis found LGG effective at 10 billion CFU/day or more, and borderline below that.
Any time of day
Capsule standardized to ATCC 53103
and 6 more not shown
2-4 weeks
4-8 weeks
4-12 weeks
During the antibiotic course
During hospital stay
n/a
n/a
Daily oral iron supplementation during pregnancy
The Cochrane database of systematic reviews (2024) · Meta analysis · n=48971
There is probably little to no difference in maternal death (2 versus 4 events, RR 0.57, 95% CI 0.12 to 2.69; 3 trials, 14,060 women; moderate-certainty evidence).
The Prevalence of Anemia among Pregnant Women in China: A Systematic Review and Meta-Analysis
Nutrients (2024) · Meta analysis · n=1376204
The results showed that the prevalence of anemia, ID, and IDA among pregnant women in China were 30.7% (95% CI: 26.6%, 34.7%), 45.6% (95% CI: 37.0%, 54.2%), and 17.3% (95% CI: 13.9%, 20.7%), respectively.
Treatment for women with postpartum iron deficiency anaemia
The Cochrane database of systematic reviews (2024) · Meta analysis · n=4558
Intravenous iron versus oral iron supplementation The evidence is very uncertain about the effect of intravenous iron on mortality (risk ratio (RR) 2.95, 95% confidence interval (CI) 0.12 to 71.96; P = 0.51; I² = not applicable; 3 RCTs; 1 event; 572 women; very low-certainty evidence).
Lactobacillus rhamnosus GG versus Placebo for Acute Gastroenteritis in Children.
N Engl J Med (2018) · Rct · n=971
Primary outcome (modified Vesikari score >=9 within 14 days): 11.8% with LGG vs 12.6% placebo; RR 0.96 (0.68-1.35), P=0.83
Systematic review with meta-analysis: Lactobacillus rhamnosus GG in the prevention of antibiotic-associated diarrhoea in children and adults.
Aliment Pharmacol Ther (2015) · Meta analysis
Antibiotic-associated diarrhea fell from 22.4% to 12.3%; RR 0.49 (0.29-0.83) pooled across 11 RCTs, n=1,308 (12 RCTs, n=1,499 included overall)
Probiotics for treating acute infectious diarrhoea.
Cochrane Database Syst Rev (2020) · Meta analysis
In studies at low risk of bias, no difference in diarrhea lasting >=48 hours (RR 1.00, 0.91-1.09; moderate certainty)
Iron has a higher evidence score (9/10 vs 6/10) and wins in 2 of 3 categories.
For support immune system, L. rhamnosus GG has a higher relevance score (38 vs 20).
No documented interaction was found in the data searched. This does not establish that this exact combination is safe.
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The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.