Tree nut and peanut allergies are relatively common and some evidence suggests that they are increasing.

Although botanically unrelated, tree nut and peanut allergies commonly co-exist. Reactions to tree nuts, similar to peanuts, can be life-threatening and may occur with very small doses. For this reason, people with a nut allergy (or any other food allergy) must completely avoid the allergen.

How many people are affected by nut allergy?

Prevalence data for nut allergy, and in particular tree nut allergy, is limited. Based on self-reported allergy in primary school aged children, allergy to any tree nut has been reported as 1.8 – 2% in children. For adults, studies indicate 1.1 – 2% of the population are affected.

What are the symptoms?

The allergic response involves the release of histamine and other inflammatory markers that can have effects seen in the skin, gastrointestinal, respiratory and cardiovascular systems of the body. 

Common allergy symptoms include:

  • Hives (rash and itching on the skin) 
  • Eczema (red, itchy, inflamed skin)
  • Vomiting.

Severe symptoms are more uncommon and include:

  • Difficulty in breathing, due to swelling of the mouth and throat
  • Anaphylaxis – dilation or constriction of blood vessels. This results in swelling which can restrict airways and/or cause a serious drop in blood pressure (anaphylactic shock), which may ultimately cause death.

Did you know? The most common triggers of food allergy are egg, cows’ milk (dairy), peanut, tree nuts, sesame, soy, wheat, fish and other seafood. But almost any food can cause an allergic reaction, including fruits. Those most likely to cause anaphylaxis are peanuts, tree nuts, shellfish, milk and egg. Individuals are less likely to outgrow allergies to peanut, tree nut, seeds and seafood.

How are food allergies diagnosed?

A true (IgE-mediated) food allergy is diagnosed through a detailed medical history, physical examination and allergy testing.

Allergy tests include a skin prick test (SPT) or blood test to measure IgE levels and, when necessary, an oral food challenge.

A medically-trained allergy specialist should always be involving in diagnosing any food allergy.

Nuts during pregnancy and breastfeeding

The Australasian Society of Clinical Immunology and Allergy (ASCIA) ‘Infant Feeding and Allergy Prevention’ guidelines [3] state:

Exclusion of any particular foods (including foods considered to be highly allergenic) from the maternal diet during pregnancy or breastfeeding is not recommended, as this has not been shown to prevent allergies.”

In other words, the guidelines recommend including allergenic foods (like nuts) whilst pregnant and throughout breastfeeding. 

When can children start eating nuts?

Nut products (such as nut butters, pastes and flours) can be introduced to infants at around 4-6 months – and should ideally be a part of their diet by 12 months.

For healthy infants, the National Health and Medical Research Centre (NHMRC) recommends exclusive breastfeeding, and then introducing solids – when the infant is ready, at around 4-6 months (but not before 4 months) – with no specific age recommendations for any particular foods [4].

The ASCIA Infant Feeding and Allergy Prevention guidelines support these recommendations [3]. The ASCIA advice includes:

  • When your infant is ready, at around 6 months, but not before 4 months, start to introduce a variety of solid foods.
  • Introduce foods according to what the family usually eats, regardless of whether the food is considered to be a common food allergen.
  • Unless there is an allergic reaction to the food, continue to give the food to your baby regularly (twice weekly), as part of a varied diet. 

The guidelines recommend starting children on allergenic foods, including tree nuts and peanuts, by 12 months.

Studies suggest delaying the introduction of solid foods, or specific allergenic foods, to infants (that is, after 12 months) is not protective and may in fact increase the chance of developing a food allergy [5, 6]. 

Australian infant feeding guidelines changed in 2016 to recommend starting children on allergenic foods earlier (by age 12 months). The Australian-based EarlyNuts study suggests parents have embraced this advice, with the earlier introduction of peanuts leading to a 16% decrease in peanut allergy [7].

How to start infants on nut products

In line with the NHMRC and ASCIA recommendations, nut butters, pastes and flours can be introduced to infants at around 6 months, but not before 4 months – just like other foods.

As a guide, mix a small amount (¼ teaspoon) of smooth nut butter/paste into your baby’s usual food (such as vegetable puree). If there is no allergic reaction, gradually increase the amount, such as ½ teaspoon the next time.

Do not give whole nuts or nut pieces to children until around 5 years, to reduce the risk of choking.

Nuts in schools

Both ASCIA and many state government health departments do not recommend blanket food bans or attempts to prohibit the entry of particular foods, such as peanuts and tree nuts, into schools.

For example, the NSW Government states:

“A blanket ban on peanuts, tree nuts and nut products within the school is not required but may be agreed to by a school and its community”.

They state that such ‘bans’ are difficult to enforce, and may also lead to a false sense of security, among students and their parents, about exposure to peanuts and tree nuts within the school. There is also a lack of evidence to support the effectiveness of such measures. 

Instead, such groups recommend that schools must not use peanuts, tree nuts or any nut products in curriculum or extracurricular activities.

References

  1. Willers SM., et al. Maternal food consumption during pregnancy and asthma, respiratory and atopic symptoms in 5-year-old children. Thorax, 2007. 62(9):773-9.
  2. Maslova E., et al. Peanut and tree nut consumption during pregnancy and allergic disease in children-should mothers decrease their intake? Longitudinal evidence from the Danish National Birth Cohort. J Allergy Clin Immunol, 2012. 130(3):724-32.
  3. ASCIA. Guidelines: Infant feeding and allergy prevention. ASCIA 2020. http://www.allergy.org.au/patients/allergy-prevention/ascia-guidelines-for-infant-feeding-and-allergy-prevention
  4. NHMRC. Eat for Health: Infant Feeding Guidelines Summary, NHMRC Council, Editor. 2013, Commonwealth of Australia: Canberra.
  5. Koplin JJ., et al. Can early introduction of egg prevent egg allergy in infants? A population-based study. J Allergy Clin Immunol, 2010. 126(4):807-13.
  6. Du Toit G., et al. Early consumption of peanuts in infancy is associated with a low prevalence of peanut allergy. J Allergy Clin Immunol, 2008. 122(5):984-91.
  7. Soriano V., et al. Has the prevalence of peanut allergy changed following earlier introduction of peanut? The EarlyNuts Study. J Aller Clin Immun, 2021. https://www.jacionline.org/article/S0091-6749(20)31772-3/fulltext#secsectitle0020
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