Randomised controlled trialindependent cross-checkfull text checked★ key study I-LEG-11 in-depth review
Early peanut prevents allergy
Randomized trial of peanut consumption in infants at risk for peanut allergy.
Overview
Du Toit G et al.. N Engl J Med 2015 · PMID 25705822 · DOI 10.1056/NEJMoa1414850
Babies at high risk who ate peanut early developed far less peanut allergy than those who avoided it.
Does the study support the specific claim? No · Methodological quality: high
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Prevent peanut allergy
- How was the study done?
RCT
- How many people, animals or samples were studied?
640 infants
- What was actually found?
Less allergy with early peanut
- How large was the observed effect?
13.7% vs 1.9%
- What do the results mean in everyday life?
Avoidance can backfire.
- What are the study's limitations?
High-risk infants only
- What does it say about Elawady's specific claim?
Contradicts blanket avoidance
- Do the results apply to Germany and Europe?
High
- What can explicitly not be concluded from this study?
Cannot address adults.
Scientific in-depth review
1. Full reference
- Authors
- Du Toit G et al.
- Journal
- N Engl J Med
- Year
- 2015
- Identifier
- PMID 25705822 DOI 10.1056/NEJMoa1414850
- Verification
- verified – PubMed efetch 2026-10-25
- Retracted
- no
- Corrections
Erratum published (N Engl J Med 2016;375:398)
- Extent checked
- full text
- Conflicts of interest and funding
NIAID (NO1-AI-15416, UM1AI109565, HHSN272200800029C), Food Allergy Research and Education, MRC and Asthma UK, UK Department of Health/NIHR BRC, National Peanut Board, UK Food Standards Agency; peanut snack bought at discounted rate from the manufacturer, which had no role in design or analysis. One author holds stock/options in DBV Technologies; another received grant support and study materials from companies.
2. Research question
Does early peanut consumption prevent allergy in high-risk infants?
3. Study design and population
- Study design
- Randomised controlled trial – Randomised, open-label, controlled trial (LEAP), single site, two independently powered cohorts stratified by baseline skin-prick test (NCT00329784)
- Population
Infants aged 4 to <11 months with severe eczema, egg allergy or both; skin-prick wheal 0 mm (n=542) or 1-4 mm (n=98); infants with wheals >4 mm (76/834 screened, 9.1%) excluded
- Country
United Kingdom (single site, St Thomas' Hospital Children's Allergy Service, London)
- Period
Enrolment December 2006 - 6 May 2009; follow-up to 60 months of age
- Sample size
640 randomised (319 to consumption); ITT 530 SPT-negative + 98 SPT-positive; 617 assessed by oral food challenge; 98.4% retention
- Inclusion and exclusion criteria
Severe eczema and/or egg allergy, age 4-<11 months; exclusion of SPT wheal >4 mm
4. Methods and endpoints
- Exposure / intervention
Consumption of >=6 g peanut protein/week in >=3 meals (mainly Bamba or smooth peanut butter) until 60 months, after negative baseline challenge
- Comparator
Peanut avoidance until 60 months
- Endpoints
Peanut allergy at 60 months by oral food challenge (5 g open or 9.4 g double-blind placebo-controlled challenge; algorithm for 11 inconclusive); immune markers; adverse events
- Statistical methods
ITT chi-square per cohort; per-protocol and worst-case imputation sensitivity analyses; power 89% (SPT-negative) and 80% (SPT-positive)
5. Actual results
- Results
SPT-negative cohort (n=530): peanut allergy 13.7% avoidance vs 1.9% consumption; absolute difference 11.8 points (95% CI 3.4-20.3), P<0.001; relative reduction 86.1%. SPT-positive cohort (n=98): 35.3% vs 10.6%; difference 24.7 points (4.9-43.3), P=0.004; relative reduction 70.0%. Per-protocol and worst-case analyses consistent. No deaths; no difference in hospitalisation or serious adverse events; more total (mostly mild) adverse events with consumption (4527 vs 4287, P=0.02). 7 consumers reacted at baseline challenge and 9 discontinued.
- Absolute risks
SPT-negative: 13.7% vs 1.9% (absolute difference 11.8 percentage points, 95% CI 3.4-20.3; NNT about 8.5); SPT-positive: 35.3% vs 10.6% (24.7 points, 4.9-43.3; NNT about 4)
- Authors' conclusion
Early, sustained peanut consumption in high-risk infants markedly reduced peanut allergy at 60 months and modulated immune responses; deliberate avoidance appears counterproductive.
6. Strengths
- Randomised with high retention (98.4%)
- Objective primary outcome by oral food challenge (mostly double-blind placebo-controlled)
- Adherence verified by FFQ and bed-dust peanut levels
- ITT, per-protocol and worst-case analyses concordant
7. Weaknesses
- Open-label; no placebo
- Only high-risk infants; those with SPT >4 mm excluded
- Single site
- Sex imbalance (64.8% vs 55.2% male)
- Partial industry-related funding (National Peanut Board)
8. Risk of bias
- Orienting tool
- RoB 2
- Type of assessment
- structured assessment based on the full text by a single reviewer (no formal double review)
- Full formal assessment
- no
- Overall risk of bias
- low
- Rationale
Single-reviewer structured RoB 2 judgement from full text; not formal (needs two independent reviewers and protocol cross-check). Open-label design is mitigated by an objective challenge-based outcome.
| Domain | Judgement | Rationale |
|---|---|---|
| D1 Randomisation process | low | Randomised within strata; groups balanced except modest sex imbalance. |
| D2 Deviations from intended interventions | some concerns | Open-label; 92% adherence; ITT analysis appropriate for assignment effect. |
| D3 Missing outcome data | low | 98.4% retention; worst-case imputation consistent. |
| D4 Measurement of the outcome | low | Oral food challenge, double-blind placebo-controlled for all but low-likelihood participants; objective endpoint. |
| D5 Selection of the reported result | low | Registered trial with published protocol; prespecified primary outcome per cohort. |
Full-text review (25 October 2026): Verified UK single site and enrolment period; added absolute differences with 95% CIs (11.8, 3.4-20.3; 24.7, 4.9-43.3), adverse-event data, exclusions, funding incl. National Peanut Board and author COI; RoB 2 domains (overall unchanged: low).
9. Assessment of the statistical interpretation
Large absolute and relative effects with CIs excluding no effect in both cohorts; effects robust in sensitivity analyses.
10. Relevance to the specific claim
Shows avoidance in infancy can increase allergy (C-LEG-11).
11. Independent contrary findings
None.
12. Transferability to Germany and Europe
High.
13. Overall methodological judgement
Key safety evidence.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | high |
| Risk of bias | low |
| Precision of results | high |
| Directness | direct |
| Reproducibility | replicated |
| Consistency with the overall evidence | consistent |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Generalisation to low-risk infants and to infants with SPT >4 mm; persistence after stopping consumption (addressed in LEAP-On).
15. Linked fact checks
- Peanut leads all food-anaphylaxis fatalities; peanut and tree nuts caused more than 90% of food-anaphylaxis deaths in the US registry. – Studies contradicting or limiting the claim