Perspectives from a dietitian: Case studies of true versus perceived food hypersensitivity

Community and hospital-based dietitians are probably the only qualified healthcare practitioners that frequently encounter true and perceived food hypersensitivity on a very regular basis. 

Ireland is among the top-ranking countries worldwide that uses Google to self-source food allergy information. This is unsurprising given that the HSE had, until recently, never addressed allergy as a specialty. 

Food allergy services in Ireland

Despite a Comhairle na nOspidéal report and recommendation in 2000¹ for a national immunology service, just two services for children exist, covering Dublin and Cork, with a very limited service in Louth, Galway and the midlands. Consultant immunologists in Dublin, Cork and Galway struggle to provide adult food allergy services as part of a much wider remit. Food allergy in Irish children has a challenge proven prevalence rate of over 4% at age 22. It causes great anxiety and distress. Proven food intolerance prevalence rates are not available and much more difficult to assess. 

Patients will only benefit from advice and dietary modification that is evidence-based, safe and individualised. Healthcare staff including dietitians, especially those who work in the community, are best placed to identify, diagnose and manage cases.

Having the skills, competence and confidence to interpret the hypothesis of a food hypersensitivity that is presented will help manage the patient’s expectations and indicate the need for a therapeutic diet. The Irish Food Allergy Network³  (IFAN) website is intended as a support in this regard.

The difference between allergy and intolerance

The challenge for the dietitian is in accurately defining and managing food hypersensitivity especially when patients have received faulty or incorrect information. Food hypersensitivity is an umbrella term that includes allergy and intolerance.⁴

Food allergy involves the immune system reacting to food and is classified as either IgE (immediate onset) and non-IgE mediated (delayed onset). Allergy symptoms can affect skin, gut, circulation and airway. It can be life-threatening in some, but not all instances. 

Food intolerance is a non-immune mediated reaction to certain food ingredients or additives. Symptoms usually mainly affect the gut, can be very irritating and unpleasant, but non-life threatening. 

Dietetics for food hypersensitivity usually hinges around partial or total food exclusion while ensuring that nutritional adequacy is maintained without compromising health, quality of life, normal growth and development in children. Removing any food from the diet is a big deal. It can result in nutrition compromise and aversive food and eating behaviours. There are cost implications and elimination diets require a level of literacy and comprehension on the part of the patient.

Asking what happens if this food is removed and what happens if the food is encountered helps identify risk and the degree of food exclusion required. Exclusion can range from absolute avoidance to defined amounts of cooked food. 

Lactose intolerance

Lactose intolerance is a common referral to dietitians. Lactose is an important carbohydrate. Reducing or removing it from the diet should not be undertaken without clear indication. It’s a specific nutrient for infancy, supplying about 40% of energy needs. It also has an important role in facilitating calcium, magnesium, zinc and iron absorption and a normal healthy gut by promoting the growth of bifidobacterium, and providing galactose which is incorporated directly as galactolipids into the tissues of the central nervous system. 

Secondary lactose intolerance is the form most frequently encountered in Ireland. Invasive testing is rarely needed. It is easily distinguished because it occurs in those who have previously tolerated lactose without difficulty. It occurs as a result of inflammation or structural damage to the small intestinal mucosa due to bacterial or viral illness. It is transient and usually resolves within a few weeks. Diagnosis depends on self-reported symptoms, not all of which can be assessed objectively. Lactose elimination is not curative and not always necessary. Lactase enzyme supplementation and lactose-free dairy products may negate the need for dairy avoidance. Normal diet should be resumed once symptoms have resolved. There is no indication for discontinuing breastfeeding in favour of lactose-free infant formula unless medically indicated. 

Primary lactase deficiency affects 4-5% of the population, in the majority of cases symptoms may not develop until late childhood or adulthood.⁵ Primary lactase deficiency is not an absolute condition. In most instances individuals can tolerate daily doses of 12-15g.^6,7

A standard 200ml glass of milk contains approximately 9-10g of lactose. The content in yogurt and cheese is considerably less (5.9g in 125g pot of plain whole milk yogurt and 0.03g in 25g
of cheddar cheese) and lower in lactose-free dairy products. In both of the above, intake versus symptoms should be used to direct lactose reduction or exclusion.

Congenital absence of intestinal lactase is a rare but severe condition and presents in the neonatal period with loose stools and potential for failure to gain weight, with poor growth and lifelong symptoms. Lifelong and strict avoidance is indicated.

A common food allergy myth

Consumption of milk and dairy products leads to mucus in the airway. This is a common food allergy myth and one for which dietitians will be frequently consulted. This was addressed and refuted in a review by Wahn⁸ in 2005, which found that milk consumption does not lead to mucus production or occurrence of asthma. It’s a very useful reference article for dietitians.

The single and most beneficial ‘test’ for food hypersensitivity is the story behind it. A focused clinical history, (a proforma of which is available at ifan.ie/wp-content/uploads/2013/10/patient-history-form.pdf) will help distinguish intolerance from immediate and delayed food allergy and direct the need for testing.

Position statement on allergy testing

Following review of the indications and rationale for safety and costs of testing for food allergy and food intolerance and in accordance with the available evidence and current best practice, IFAN produced a position statement on allergy testing to guide healthcare professionals, available at fan.ie/wp-content/uploads/2013/12/Allergy-testing-position-statement.pdf

Dietitians have a key role in food allergy, where the focus needs to be positive and centred on maximising quality of life. As part of a multidisciplinary team, the dietitian will help patients identify and quantify risk and take measures to reduce and mitigate against it.

This can include:

• Reintroducing all non-allergic foods that were removed but are not implicated

• Time-defined food elimination and rechallenge

• Label reading for allergen identification in food and non-foods

• Tolerance induction using milk and egg ladders

• Promoting normal age appropriate eating and feeding skills

• How and where to eat out safely, including school, parties, and playdates

• Identification and management of an allergic reaction

• Rationale for adrenaline autoinjector prescription and use.

The Paediatric Dietitians Interest Group of the INDI produced an excellent resource information pack ‘food allergy in children’ in 2011 which is available to members. It includes an overview section on living with food allergy and specific sections for milk, egg, peanut, treenut and wheat.

IFAN’s website gives free access to many resources like milk⁹ and egg¹⁰ ladders, AAI devices and training materials¹¹, and allergy management plans.¹²

References

1. http://lenus.ie/hse/bitstream/10147/44739/1/6311.pdf

2. Kelleher et al. Skin barrier impairment at birth predicts food allergy at 2 years of age. J Allergy Clin Immunol 2016

3. www.ifan.ie

4. EAACI. http://www.eaaci.org/attachments/304_English.pdf

5. Ingram CJ et al. Lactose digestion and the evolutionary genetics of lactase persistence.
Human Genetics 2009; 124: 579-591

6. Shaukat A et al. Systematic review: effective management strategies for lactose  intolerance. Ann Inter Med 2010; 152: 797-802 

7. European Food Safety Authority (EFSA) Panel on Dietetic Products, Nutrition  and Allergies. Scientific opinion on lactose thresholds in lactose intolerance and galactosaemia. EFSA Journal 2010; 8(9):1777 

8. Wuthrich et al. Milk Consumption Does Not Lead to Mucus Production or Occurrence of Asthma. J Am Coll Nutr 2005, Vol. 24, No. 6, 547S–555S

9. http://ifan.ie/milk-classification-ladder/

10. http://ifan.ie/egg/egg-classification-ladder/

11. http://ifan.ie/adrenaline-training-allergy-education/

12. http://ifan.ie/managing-an-allergic-reaction-sample-emergency-plan/