Introducing Allergens

The advice reversed, and this is the current version

If you were told to keep peanut away from your baby, you were told what national bodies genuinely used to recommend. The American Academy of Pediatrics describes the old position in its own words: "For many years, experts thought that the best way to fight peanut allergy was to avoid peanut products in the first years of life." Its 2000 guidance recommended avoidance until age three for high-risk children.

That has gone. The AAP now states: "newer research found no benefit to delaying the introduction of allergenic foods." And the NHS goes further than neutral — it says delay may actively harm: "Evidence has shown that delaying the introduction of peanut and hen's eggs beyond 6 to 12 months may increase the risk of developing an allergy."

Allergy UK says the same on both counts: there is "no evidence to support delaying the introduction of these foods beyond six months of age", and "delaying their introduction past 12 months may actually increase a child's risk of developing an allergy to that food".

What changed the guidance

The pivot came from a trial. The AAP describes the Learning Early About Peanut Allergy study, which compared infants who ate peanut products with infants who did not: "only 3 percent of the kids who ate peanut products were allergic to them — compared with 17 percent of those who didn't eat peanuts." That result produced the 2017 Addendum Guidelines for the Prevention of Peanut Allergy and, in time, the change you now see on the NHS website. The AAP's summary of the effect: "In 2015, a major study found that early peanut introduction — with continued, regular servings — prevented peanut allergy in infants."

Anyone still telling you to delay allergens is working from advice that was superseded roughly a decade ago.

When and what to introduce

The NHS: "When you start introducing solid foods to your baby from around 6 months, introduce the foods that can trigger allergic reactions 1 at a time and in very small amounts so that you can spot any reaction." Its list of foods to introduce from around six months, "just like any others":

• cows' milk (in cooking or mixed with other food — not as a main drink until 12 months)
• eggs
• foods containing gluten, including wheat, barley and rye
• nuts and peanuts, served crushed or ground
• seeds, served crushed or ground
• soya
• fish
• shellfish, never raw or lightly cooked

The AAP's list is the same family of foods: "egg, nut products, yogurt or other dairy, wheat, sesame, soy, fish and shellfish".

How much, and in what form

The AAP gives concrete portions: about "2 teaspoons of peanut butter", nut butters such as cashew or sesame tahini, and "about 1/3 of a well-cooked egg". For peanut specifically: "one safe way is by mixing and thinning out a small amount of peanut butter in cereal, pureed fruit or yogurt."

The form matters as much as the food. "Do not feed whole peanuts or tree nuts to babies or young children — they are choking hazards." The NHS says the same: whole nuts should be crushed or flaked for under-fives, and peanut butter should never be given by itself.

Keeping it in the diet

Introduction is not a one-off test. The NHS: "Once introduced and if tolerated, keep offering those foods as part of your baby's usual diet to minimise the risk of allergy." Allergy UK is more specific: continue to include them "ideally at least twice a week, to ensure that your baby remains tolerant to that food". Allergy UK also suggests introducing new allergens one at a time over three days, moving on to the next if there are no symptoms.

Babies at higher risk

The NHS: "If your baby already has an allergy, such as a diagnosed food allergy or eczema, or if you have a family history of food allergies, eczema, asthma or hay fever, you may need to be particularly careful when introducing foods. Talk to your GP or health visitor first."

The AAP defines the high-risk group as babies who have or had "severe, persistent eczema or an immediate allergic reaction to any food". Under the 2017 addendum guidelines it describes three pathways: for severe eczema and/or egg allergy, testing for peanut allergy is recommended and introduction happens between four and six months; for mild to moderate eczema, no testing is needed and introduction is around six months; for babies with no eczema or food allergy, peanut products can be introduced according to family preference and cultural practice.

Allergy UK adds a practical note: "It is preferable to wait until eczema is under control before introducing allergenic foods", and that higher-risk babies "may benefit from earlier introduction of egg and then peanut".

These pathways differ between countries. If your baby has severe eczema or a known food allergy, this is a conversation with your GP, health visitor or paediatrician before you start, not an article to follow unaided.

What a reaction looks like

The NHS lists: diarrhoea or vomiting, a cough, wheezing and shortness of breath, an itchy throat and tongue, itchy skin or a rash, swollen lips and throat, a runny or blocked nose, and sore, red, itchy eyes.

Practical points that reduce the guesswork: introduce a new allergen at home rather than out, earlier in the day rather than at bedtime, and only one new one at a time so a reaction has an obvious culprit.

When to speak to a health visitor or doctor

Call 999 immediately for a severe reaction — the NHS notes that in a few cases foods can cause anaphylaxis, which can be life-threatening. Swelling of the lips, tongue or throat, difficulty breathing, wheeze, a sudden widespread rash with distress, floppiness or collapse are all emergencies.

Book a GP or health visitor appointment before starting allergens if your baby has moderate or severe eczema, an existing food allergy, or a strong family history. Book one afterwards if you have seen a mild reaction, if symptoms keep recurring with a particular food, or if you have cut a food out and are unsure how to reintroduce it. Do not remove a major food group from your baby's diet long-term without advice.