The story of how peanut introduction advice reversed itself is the most dramatic policy shift in paediatric feeding in a generation. The science is now settled, but it has taken years for it to translate from research into the kitchen. Most parents are no longer told to delay — but many still aren't sure exactly when to start, what counts as "high risk," or how to physically give peanut butter to a 6-month-old without choking them. Below is the practical version.
Healthbooq covers weaning and allergen introduction.
How the Advice Got It Backwards
Through the 1990s and 2000s, parents were advised to delay peanut and other allergens to "give the immune system time to mature." The reasoning was theoretical, and the practical effect was that peanut allergy rates roughly tripled across the western world over the same period.
The clue came from epidemiology. Israeli children, who eat Bamba (a popular peanut puff) from infancy, have peanut allergy rates around 0.17%. UK Jewish children of the same genetic background, who follow Western avoidance advice, have rates around 1.85% — a tenfold difference. Gideon Lack and his team at King's College London noticed this in the early 2000s and designed the trial that became known as LEAP (Learning Early About Peanut Allergy).
What the LEAP Trial Did
Published in NEJM in 2015. 640 infants aged 4 to 11 months who already had severe eczema, egg allergy, or both — exactly the group historically considered "too high risk" to expose to peanut. Randomised to either:
- Eat peanut regularly (Bamba peanut puffs or smooth peanut butter) — at least 6 g of peanut protein per week
- Strictly avoid peanut until age 5
At age 5:
- Avoidance group: 13.7% had peanut allergy
- Consumption group: 1.9% had peanut allergy
- Relative reduction: 81%
The follow-up trial, LEAP-On, asked what happens if you stop peanut for a year after age 5. The answer: protection persisted in most children. The tolerance learnt early was robust.
Subsequent trials (EAT, PETIT for egg, others) replicated the principle for other allergens. The mechanism is oral tolerance: gut exposure to food proteins teaches the immune system to ignore them; skin exposure through inflamed eczema without prior gut exposure teaches it to react.
What This Means for Your Baby
If your baby has no eczema or only mild eczema and no known food allergies:
- Introduce peanut, egg, cow's milk products, wheat, sesame, fish, tree nuts, and soy at home from around 6 months
- No testing needed. No specialist required. No special preparation.
- One new allergen at a time, watch for 2 hours, then keep going.
If your baby has moderate eczema (intermittent flares, manageable with emollient and occasional mild steroid):
- Same approach — introduce at home from 6 months.
- Treating the eczema well (regular emollient, prompt steroid for flares) is itself part of allergy prevention.
If your baby has severe eczema (extensive, requiring daily or near-daily potent topical steroids) or already-diagnosed egg allergy:
- Speak to your GP or health visitor before peanut introduction. Some are referred for an allergy clinic visit, sometimes with a skin-prick test or supervised first feed.
- Don't delay solids generally — that part of weaning starts at the same 6-month mark.
How to Actually Give Peanut to a 6-Month-Old
This is where parents commonly get stuck. Peanut butter on toast is a 1-year-old's food, not a 6-month-old's. Whole peanuts are a choking hazard until at least age 5.
The practical methods:
Smooth peanut butter, thinned.- Half a teaspoon of smooth peanut butter
- Mix with 2 to 3 teaspoons of warm water, breast milk, or formula until smooth and sauce-like
- Or stir into yoghurt, baby porridge, or pureed fruit
- Offer on a small spoon
- Designed to dissolve quickly in the mouth
- Soft enough to gum even without teeth
- One puff at first
- Available in some UK supermarkets and online
- Whole peanuts (choking)
- Crunchy peanut butter (crunchy bits are also choking)
- Dry peanut powder on the tongue (can clump and choke)
- A small amount on the tip of a spoon, earlier in the day
- At home, with both parents around if possible
- Watch for 2 hours
- If tolerated, give a slightly bigger amount the next day, building up over a week
- Aim for around 2 g of peanut protein per week, in 2 or 3 servings
- That's about 2 teaspoons of smooth peanut butter, or 5 to 7 Bamba puffs, weekly
- This is the dose used in the LEAP trial; less may not maintain tolerance reliably
The Other Major Allergens
Once peanut is established, work through the others over the following weeks. The order doesn't matter; the principle (one at a time, at home, watch for 2 hours) does.
Egg. Well-cooked first — hard-boiled, scrambled until set, baked into a muffin or pancake. Once tolerated, lightly cooked egg can come in the second 6 months. Skip raw egg before 12 months (salmonella).
Cow's milk products. Yoghurt, cheese, baked milk products from 6 months. Cow's milk as a main drink — not before 12 months.
Wheat. Bread, pasta, baby porridge — usually one of the easier first allergens.
Sesame. Tahini paste smoothed thin on a piece of bread or stirred into hummus.
Tree nuts. Smooth nut butter, one nut at a time. Almond butter, cashew butter — same thinning approach as peanut.
Fish. Cooked, deboned, finely flaked. White fish first; introduce oily fish soon after.
Shellfish. Well-cooked, finely chopped, no shell pieces. Often introduced later in weaning.
Soy. Tofu, soy yoghurt, well-mashed edamame.
What a Reaction Looks Like
Mild to moderate. Hives, swelling around the mouth or face, vomiting, mild cough. These appear within minutes to 2 hours.
- Stop the food
- Antihistamine if you have age-appropriate (Piriton from 1 year)
- Same-day GP or 111 review
- Don't re-introduce that food without speaking to a clinician
Severe (anaphylaxis). Difficulty breathing, throat tightness, persistent cough, voice changes, severe vomiting, pale and floppy.
- Call 999. Lay flat, do not stand the baby up
- If an EpiPen has been prescribed, use it (mid-outer thigh, hold for 10 seconds)
- Do not re-introduce that food without specialist input
A common confound: redness around the mouth where food has touched. With acidic foods (tomato, citrus, strawberry) and sometimes with peanut butter, you can see local skin redness that is contact reaction, not allergy. It fades in 30 to 60 minutes and doesn't recur with the food eaten properly. A genuine allergic reaction usually involves more than just the area where food touched the skin.
What If My Baby Refuses?
A baby spitting peanut butter back at you is not an allergic reaction. It's a baby learning a new flavour. Some practical tips:
- Mix into something familiar. Stir half a teaspoon into yoghurt or porridge they already know
- Repeat exposure. It often takes 8 to 15 offerings of a new food before a baby accepts it; persistence is normal
- Don't make it a battle. A relaxed, no-pressure offer is more likely to be tasted than a focused one
- Bamba puffs are often more accepted than peanut butter — the texture is less unfamiliar
A baby who simply doesn't like peanut butter still needs the regular exposure to maintain tolerance. Even small amounts (a teaspoon stirred into something) count.
Common Questions
"Should I do an allergy test before introducing peanut?"- For babies without severe eczema or known egg allergy: no. Routine pre-introduction testing is not recommended; positive tests in babies who have never eaten the food often produce false positives that lead to unnecessary avoidance.
- For most babies, no — and the NHS doesn't routinely offer this. For babies in the high-risk groups (severe eczema, existing egg allergy), specialist allergy services may offer supervised introduction.
- A sibling with severe peanut allergy doesn't automatically place a baby in the high-risk category, but worth a GP conversation. Many parents in this situation choose to introduce in a clinic setting; many introduce at home with no problems.
- Yes — wait until they're well (no fever, no vomiting, eczema reasonably settled) before any first allergen introduction. Don't delay beyond what's needed for the illness, though.
- Mostly yes — but keep allergens in the diet at least weekly through the first few years. Tolerance fades with avoidance.
When to See an Allergy Clinician
Your GP can refer for:
- Severe eczema in a baby under 6 months
- A clear allergic reaction to any food at any age
- Suspected non-IgE allergy (persistent vomiting, blood-streaked stools, failure to thrive)
- Significant family history with parental concern
NHS waiting times vary. If anaphylaxis has occurred, GP can prescribe adrenaline autoinjectors at the first appointment without waiting.
Key Takeaways
For 20 years, parents were told to avoid peanuts and other allergenic foods until well after the first birthday. The LEAP trial in 2015 showed that early introduction reduces peanut allergy by 81% in babies at high risk. Current NHS, BSACI, and NICE guidance: introduce peanut, egg, cow's milk products, wheat, sesame, fish, tree nuts, and soy from around 6 months alongside standard weaning, and keep them in the diet at least weekly. The only babies who need specialist input before peanut introduction are those with severe eczema or already-diagnosed egg allergy — the group LEAP studied. Everyone else: smooth peanut butter on a teaspoon, mixed into a bit of yoghurt, in the morning, watch for 2 hours.
