Why Dietitians Don’t Recommend Food Intolerance Tests (And What to Do Instead)

If you’ve been struggling with bloating, fatigue, headaches, stomach pain, or skin flare-ups, it’s understandable to want answers quickly. A quick online search will likely lead you to food intolerance tests claiming to identify “hidden sensitivities” using blood samples, hair strands, nail clippings or even bioresonance devices.

The problem? These tests are not scientifically validated — meaning any evidence-based dietitian or medical professional does not recommend them and they are deemed invalid by all major allergy organisations.

In this article, we’ll explain the difference between food allergies and food intolerances, why many commercial intolerance tests are unreliable, and what evidence-based approaches actually help identify trigger foods safely and effectively.

Food Allergy vs Food Intolerance: What’s the Difference?

Although the terms are often used interchangeably, food allergies and food intolerances are very different conditions.

Food Allergies

A food allergy involves the immune system. In most cases, the body produces an antibody called Immunoglobulin E (IgE) in response to a food protein.

Symptoms can appear rapidly and may include:

• Hives or skin rash

• Swelling of the lips, face, or throat

• Wheezing or difficulty breathing

• Vomiting

• Anaphylaxis (a severe, potentially life-threatening reaction)

Common food allergens include:

• Peanuts

• Tree nuts

• Milk

• Eggs

• Shellfish

• Wheat

• Soy

Food allergies should always be assessed and diagnosed by a doctor or allergy specialist.

Food Intolerances

Food intolerances do not involve the same immune response as allergies. They are generally related to difficulties digesting or processing certain foods or food components.

Symptoms are usually less immediate and may include:

• Bloating

• Gas

• Diarrhoea

• Abdominal pain

• Nausea

• Fatigue

• Headaches

Examples of food intolerances include:

• Lactose intolerance

• Sensitivity to caffeine

• Some reactions to high FODMAP foods

• Reactions to certain food additives

Food intolerances are rarely dangerous, but they can significantly affect quality of life.

Why Dietitians Don’t Recommend Most Food Intolerance Tests

Many commercially marketed food intolerance tests claim to identify problem foods quickly and easily. However, the majority lack strong scientific evidence and are not recommended by dietitians, allergy organisations, or medical bodies.

Here are some of the most common examples.

1. IgG Blood Testing

IgG food sensitivity testing is one of the most heavily marketed intolerance tests and to be honest, they seem legit because it requires a blood test. 

These tests typically measure Immunoglobulin G (IgG) antibodies to various foods and classify foods as “safe,” “borderline,” or “reactive.”

Why It’s Problematic

Research shows that IgG antibodies are often a normal sign of exposure to food — not intolerance.

In fact, having IgG antibodies to foods may simply indicate that you regularly eat and tolerate those foods.

This means the test can incorrectly label healthy foods as “problem foods,” leading people to unnecessarily eliminate foods.

2. Hair Analysis Testing

Hair testing claims to identify food sensitivities, nutrient deficiencies, or intolerances through a strand of hair (or nail clipping). 

Why It’s Not Reliable

There is no good scientific evidence that hair analysis can accurately diagnose food intolerances.

Results are often inconsistent and can vary dramatically between laboratories. Some investigations have even shown that fake hair samples or repeated samples from the same person can produce completely different results.

3. Bioresonance and Electrodermal Testing

These tests use electrical currents, handheld devices, or energy frequency measurements to claim they can identify food sensitivities.

The Issue

These methods are not scientifically validated for diagnosing food intolerances or allergies.

Despite impressive marketing claims, there is no reliable evidence that these devices can accurately identify problematic foods.

The Risks of Unvalidated Food Intolerance Testing

While these tests may seem harmless, they can actually create more problems than solutions.

1. Unnecessary Food Restrictions

People are often advised to avoid dozens of foods after receiving test results.

This can lead to:

• Overly restrictive diets

• Fear around eating

• Social stress

• Reduced enjoyment of food

2. Nutritional Deficiencies

Cutting out major food groups without proper guidance can increase the risk of nutrient deficiencies.

For example:

• Avoiding dairy may reduce calcium intake

• Removing wheat products can lower fibre intake

• Eliminating multiple foods may reduce overall diet quality

3. Delayed Medical Diagnosis

Symptoms blamed on “food intolerances” may actually be caused by:

• Coeliac disease

• Irritable bowel syndrome (IBS)

• Inflammatory bowel disease

• Endometriosis

• Gallbladder disease

• Anxiety or stress-related gut symptoms

Relying on inaccurate testing can delay appropriate medical care.

What is considered evidence-based?

Condition	Evidence-based approach
Lactose intolerance	Lactose hydrogen breath test or dietary elimination/challenge
Fructose malabsorption	Hydrogen breath test
Celiac disease	Blood tests for celiac antibodies plus medical evaluation; sometimes intestinal biopsy
Food allergy	Medical history, skin-prick testing, specific IgE testing, and supervised oral food challenge
Suspected non-allergic food intolerance	Structured elimination diet followed by reintroduction/challenge

**A structured elimination diet should only ever be completed under the guidance of a Dietitian after having ruled out other medical conditions such as Coeliac Disease and IBD. 

The Bottom Line

Food intolerance tests may promise quick answers, but many popular methods — including IgG blood testing, hair analysis, bioresonance, and kinesiology — are not supported by strong scientific evidence.

Rather than spending money on unreliable testing, an evidence-based approach with a qualified healthcare professional is far more likely to provide meaningful answers and long-term symptom relief.

If you suspect certain foods are affecting your health, the best next step is working with a dietitian who can guide you through a structured and scientifically supported process.