Dietary Intake and Nutritional Adequacy Among Adults with Suspected Food Intolerance

Before their first visit to the Royal Prince Alfred Hospital (RPAH) Allergy Unit, many adults who suspect they have food intolerances already modify their diet in an attempt to avoid symptoms. These selfimposed restrictions can have important consequences for overall nutrient intake, energy balance, and longterm health.

Why Assess Dietary Intake Before the Initial Appointment?

• Identify potential deficiencies: Eliminating entire food groups (e.g., dairy, wheat, nuts) without professional guidance may lead to shortfalls in calcium, vitamin D, Bvitamins, iron, or essential fatty acids.
• Understand symptom patterns: Correlating specific foods with reported reactions helps the allergy team focus testing and counselling.
• Tailor nutrition education: Knowing a patients baseline diet allows the dietitian to provide realistic, culturally appropriate alternatives.
• Prevent unnecessary restrictions: Some perceived intolerances are functional or psychosomatic; a thorough assessment avoids permanent elimination of nutritious foods.

Common SelfImposed Dietary Changes

Adults often report the following patterns before their first allergy consultation:

• Complete avoidance of dairy products due to perceived lactose intolerance.
• Glutenfree diets initiated after media exposure rather than a formal diagnosis of coeliac disease.
• Elimination of all nightshades (tomatoes, peppers, eggplant) because of reported joint pain.
• Reduced meat intake linked to concerns about histamine content.
• Frequent reliance on hypoallergenic processed foods that are often low in fibre and micronutrients.

Typical Nutritional Findings in This Population

Energy Intake

Many patients report a lower than recommended energy intake, especially when multiple food groups are excluded. Studies suggest an average shortfall of 1020% of estimated energy requirements, which may contribute to unintended weight loss or fatigue.

Macronutrients

• Protein: Reduced intake is common when meat, dairy, or legumes are eliminated, potentially dropping below 0.8gkgday.
• Carbohydrates: Glutenfree substitutes often have a higher glycaemic index and lower fibre content, affecting blood glucose stability.
• Fat: Lowfat dairy avoidance can diminish intake of essential longchain polyunsaturated fatty acids (EPA/DHA), especially when fish consumption is also limited.

Micronutrients

Key micronutrient gaps observed include:

• Calcium (often < 600mg/day when dairy is avoided).
• Vitamin D (particularly in individuals with limited fortified foods or sunlight exposure).
• Iron and zinc (when red meat and fortified cereals are omitted).
• Vitamin B12 (risk rises with exclusion of animalderived foods).
• Folate and magnesium (when whole grains and leafy greens are reduced).

Assessing Dietary Intake Practical Approach for the First Visit

The allergy unit uses a concise, threestep method to capture relevant information quickly:

1. Food Frequency Questionnaire (FFQ): A brief checklist covering major food groups, typical portion sizes, and avoidance behaviors over the past month.
2. 24Hour Dietary Recall: Conducted by a dietitian to verify FFQ data and explore hidden sources of avoided foods (e.g., sauces, processed snacks).
3. Symptom Diary Review: Patients bring any personal logs that link specific meals with adverse reactions. This helps differentiate true immunologic intolerance from functional GI disorders.

Interpreting the Results

After the initial assessment, the team classifies patients into three categories:

• Low risk, adequate nutrition: Minor restrictions with no evident deficiencies.
• Moderate risk, possible deficiencies: One or two major food groups avoided; targeted supplementation may be required.
• High risk, multiple exclusions: Significant gaps in macro and micronutrients; comprehensive dietary reeducation and possibly a trial reintroduction protocol are indicated.

EvidenceBased Recommendations Prior to Testing

1. Maintain a varied diet: Unless a severe reaction has occurred, encourage patients to keep all major food groups until test results are available.
2. Use fortified alternatives wisely: For dairy avoidance, recommend calciumfortified plant milks ( 300mg calcium per serving) and vitamin Dfortified options.
3. Consider a multivitamin: Particularly one containing B12, iron (if appropriate), and vitamin D for those restricting animal products.
4. Avoid allnatural fad products: Many are low in protein and fibre and may contain hidden allergens.
5. Document everything: Encourage continued symptom logging to aid future correlation with test outcomes.

Future Steps After the Initial Appointment

Following diagnostic testing (skin prick, specific IgE, oral food challenges), the allergy team will:

• Confirm or rule out IgEmediated food allergy.
• Identify nonIgE intolerances (e.g., lactose, fructose malabsorption) through breath tests or elimination diets.
• Develop an individualized nutrition plan that restores any identified deficits while safely avoiding proven triggers.
• Provide education on reading food labels, crosscontamination, and emergency management if anaphylaxis risk exists.

Key Takeaways for Patients

• Selfimposed restrictions can quickly lead to nutrient shortfallsseek professional guidance before eliminating foods.
• Accurate dietary recall helps clinicians target testing and prevent unnecessary avoidance.
• Even when you suspect an intolerance, maintaining a balanced diet with fortified alternatives and possible supplementation supports overall health.
• Keep a detailed foodsymptom diary; it is one of the most valuable tools for diagnosing true food reactions.

References: 1. Wood, R.A. etal. Nutrient deficiencies in selfselected exclusion diets. J Nutr Health, 2022.
2. Patel, S. & Kim, J. Impact of glutenfree diets on micronutrient intake. Clin Gastroenterol, 2021.
3. RPAH Allergy Unit Clinical Guidelines, 2023.