What is the LEAP (Learning Early About Peanut allergy) method for preventing peanut allergy in infants?

LEAP Method for Preventing Peanut Allergy

The LEAP (Learning Early About Peanut Allergy) method involves introducing peanut-containing foods to high-risk infants between 4-11 months of age, consuming at least 6 grams of peanut protein weekly (equivalent to 3 teaspoons of peanut butter) distributed over 3 or more feedings per week, which reduces peanut allergy risk by up to 80% in this population. 1

Target Population

The LEAP method specifically targets high-risk infants defined by: 1

• Severe eczema: requiring topical corticosteroids or calcineurin inhibitors for at least 12 of 30 days on 2 occasions
• Egg allergy: documented by skin prick test (SPT) wheal >6 mm to raw egg white or >3 mm to pasteurized egg white with allergic symptoms
• Age 4-11 months at time of introduction 1

Clinical Outcomes

The intervention demonstrates remarkable efficacy in preventing peanut allergy: 1

• Absolute risk reduction: 11-25% depending on baseline sensitization status
• Relative risk reduction: 70-86%
• Number needed to treat: 4-8.5 infants (lower number for those with mild baseline sensitization)
• Among infants with negative baseline SPT: peanut allergy prevalence dropped from 13.7% to 1.9% at 60 months 1
• Among infants with 1-4mm SPT wheals: prevalence dropped from 35.3% to 10.6% 1

Implementation Algorithm Based on Risk Stratification

Step 1: Perform Baseline Testing 1

Conduct peanut SPT on high-risk infants before introduction:

• SPT wheal 0-2mm OR peanut-specific IgE <0.35 kUA/L: Introduce peanut at home without further evaluation 1, 2
• SPT wheal 3-4mm: Consider supervised office feeding or allergist evaluation 1
• SPT wheal >4mm: Refer to allergist for oral food challenge before introduction 1

Step 2: Dosing Protocol 1

Administer 6-7 grams of peanut protein weekly, divided into 3 or more feedings: 1

• 1 teaspoon smooth peanut butter mixed with milk, mashed fruit, or pureed vegetables
• Bamba snack (approximately two-thirds of 1-oz bag; 21 sticks), softened with 20-30 mL water or milk for infants <7 months
• Finely ground peanuts mixed into yogurt or other foods
• Never use whole peanuts due to choking hazard 1

Step 3: Timing and Duration

• Begin between 4-6 months of age (as early as 4 months is acceptable) 1
• Continue regular consumption through at least 60 months of age 1
• The LEAP-On study confirmed tolerance persists even after 12 months of subsequent avoidance 1

Critical Safety Considerations

For infants with peanut-specific IgE <0.35 kUA/L or SPT ≤2mm: The risk of severe reaction at first introduction is extremely low—only 1 of 272 infants in LEAP experienced a mild reaction requiring antihistamine treatment. 1, 2

For infants with SPT 3-4mm: 4 of 17 infants had positive oral food challenges at baseline, but symptoms were mild and did not require epinephrine. 1

Common pitfall: Do not delay introduction beyond 11 months in high-risk infants, as this significantly increases peanut allergy risk. 1

Evidence Quality and Applicability

The LEAP trial provides Level 1 evidence from a randomized controlled trial demonstrating that early peanut introduction prevents peanut allergy in high-risk populations. 1 The NIAID expert panel guidelines (2017) incorporated these findings into formal recommendations. 1

Important limitation: The LEAP trial excluded infants with SPT >4mm and did not study general population or low-risk infants, so these recommendations apply specifically to the high-risk population described above. 1, 3

The intervention is allergen-specific—LEAP findings apply to peanut allergy prevention and should not be assumed to prevent other food allergies without separate evidence. 4