The DNA Dietitian

Book Consultation

  • By entering or providing us with your personal your data, you are allowing The DNA Dietitian to access and store your data for the purpose of dealing with your enquiry with a view to providing services to you, in accordance with our data protection, privacy and cookies policy.

    Upon submitting an enquiry via our contact form, an email will be sent to one of the team to respond. To comply with GDPR, your data will be kept for no longer than one year after your last correspondence or until you request that your personal data be deleted.

    If you instruct us to provide clinical services to you, your data will be stored for eight years in accordance with the BDA and HCPC Standards for Records and Record Keeping.

    To remove your personal data prior to this date please contact us at

  • We would also like to contact you from time to time to tell you about other services or offers that may be of interest to you and to give you updates. By ticking the box below, you consent to us contacting you for marketing purposes.

Food Intolerance Testing: Is it Scientifically Sound?


More and more people are unnecessarily eliminating foods from their diet as the result of unreliable and unscientific food hypersensitivity tests.

This article looks at the various tests available and explains what to do if you suspect a food intolerance.

The Difference between Intolerances and Allergies

A food allergy is an abnormal response to a food, triggered by the body’s immune system.

Within minutes of eating the allergen-containing food, people may experience a raised itchy red rash, swelling of the face and/or mouth and vomiting. In severe cases, it can lead to a life-threatening allergic reaction, known as anaphylaxis.

There is no cure for a food allergy, so people must avoid specific foods which they are allergic to.

Unlike food allergies, food intolerance does not involve an immune response and is therefore not life-threatening but can be unpleasant.

People with a food intolerance have difficulty digesting certain foods, often due to enzyme defects in the digestive system.

It’s worth noting that the term ‘food hypersensitivity’ refers to both food allergies and food intolerances.

Symptoms of Food Intolerances

Symptoms usually appear several hours after eating the food that you are intolerant to.

In some people, the onset of symptoms can be delayed by up to 48 hours, making it very difficult to determine which food(s) you are intolerant to.

Symptoms vary according to the intolerance, but commonly affect the digestive tract, skin and respiratory systems. They can have a severe impact on day-to-day life, which can affect your quality of life.

Lactose intolerance affects up to 25 percent of the European population, with much higher prevalence rates in people of Asian heritage.

Common symptoms of lactose intolerance include:

  • Bloating
  • Abdominal pain
  • Diarrhoea
  • Gas

Interestingly, scientists now believe that some people who test negative for coeliac disease (an autoimmune disease) using traditional methods may in fact be intolerant to gluten. Our comprehensive genetic test can potentially identify these intolerances.

Non-coeliac gluten sensitivity is thought to impact 0.5 – 13 percent of the population and common symptoms include:

  • Headaches
  • Fatigue
  • Skin rash
  • Joint Pain
  • Bloating
  • Change in bowel habits

Finally, some people are intolerance to amines, which are chemical components found in a wide variety of foods.

The ingestion of histamine-rich foods such as tomatoes, hard cheeses and alcohol can lead to highly unpleasant symptoms, such as:

  • Itching
  • Anxiety
  • Low blood pressure
  • Nausea
  • Headaches

Patients can manage their symptoms on a low-histamine diet, however this is a highly restrictive diet which must be followed for two to four weeks.

Methods of Diagnosing Intolerance

It’s difficult to estimate the prevalence of food intolerances as the symptoms widely vary.

The only way to diagnose a food intolerance is to exclude the problematic food(s) for a period of time and monitor the symptoms. This process should be supervised by a Registered Dietitian.

If symptoms improve then a food challenge is conducted. The suspect food is reintroduced gradually and symptoms are monitored.

If symptoms return then this would indicate that there is a problem with that particular food, and a person may need to reduce or avoid this particular food in the long run.

Unfortunately, unreliable and unscientific food hypersensitivity tests are being sold to the public.

According to the British Dietetic Association, some tests to avoid include:

  • IgG blood test (the only reliable blood test is an IgE test, which is carried out by doctors to diagnose food allergies)Kinesiology
  • Hair analysis
  • Leucocytotoxic or Cytotoxic test
  • Pulse test
  • Electrodermal (Vega) test

The above tests should be avoided as they have no scientific basis and can be harmful when multiple foods are excluded unnecessarily.

The Role of the Dietitian in Food Intolerance Testing

Dietitians work with you to uncover the real food culprit behind your digestive issues and other symptoms.

You may suspect a certain food but without their expert insight you don’t know. What’s more, unnecessary elimination of food(s) or food groups can put you at increased risk of nutritional deficiencies.

A Registered Dietitian will help you to manage your food intolerance through avoiding or reducing your intake of the foods which you are intolerant to. They will also help you to make suitable food substitutions so that your diet remains nutritionally adequate.

After a period of dietary elimination, they may help you to re-introduce these foods to a level which is tolerated.


Whilst a food intolerance is not life-threatening, it can significantly impact your quality of life.

If you suspect a food intolerance or food allergy, it is important that you see your Registered Dietitian and GP to discuss the use of medically-approved tests rather than relying on non-scientific food intolerance tests.

If you are diagnosed with a food intolerance or food allergy, a Registered Dietitian can give you the correct nutritional advice and ensure a well-balanced nutritional intake.

Other Posts

Read More
Articles 30/01/2024

Genetic Nutritionist: Your Guide For Better Health

Rachel Clarkson is a leading genetic nutritionist offering expert advice based on your DNA. Get in touch today.

Read More
Articles 20/12/2019

IBS Dietitian Clinic London

For those seeking an IBS clinic in London, it is essential to choose someone proven, qualified and experienced in dealing with common IBS conditions.

The DNA Dietitian's Privacy Policy and Terms

By continuing to use this site you agree to The DNA Dietitian's Terms of Service and Privacy Policy.