Food sensitivity tests and food intolerance tests are becoming increasingly popular. Many companies promise that they can determine which foods you react 'sensitive' to with a blood test, or even a strand of hair.
For people with complaints such as bloating, abdominal pain, or fatigue, this sounds appealing: finally a clear cause.
But unfortunately, most of these tests are not scientifically validated.
What do these tests measure?
Many food sensitivity tests measure IgG antibodies (Immunoglobulin G) in your blood.
IgG antibodies are proteins that your immune system produces when it is exposed to a food. They function as a sort of 'tag'.
That may sound like it indicates a problem, but it usually means the opposite.
The presence of IgG antibodies usually simply means that your body has been exposed to that food, for example, because you have eaten it recently or eat it regularly.
Why do test results often list foods you eat frequently?
People who take such a test often receive a long list of foods they should avoid.
Interestingly, that list often includes foods that they eat regularly.
This is because IgG antibodies often increase when you:
a food you have eaten recently
a food you often eat
The test can therefore simply indicate what you have eaten recently, not what your body reacts poorly to.
What does the science say?
Many medical organisations advise against the use of IgG tests to diagnose food intolerances.
These tests do measure something, but they do not measure what they claim to measure.
They cannot therefore provide a reliable diagnosis.
And hair-based food sensitivity tests?
Some companies also offer hair tests for food intolerances.
In these tests, you cut off a lock of hair and send it to a laboratory. You then receive a list of foods to which you are supposedly sensitive.
But hair is dead tissue. It contains no immune cells, no antibodies, and no reliable biomarkers.
Therefore, a hair test cannot determine how your body reacts to food.
Why these tests can be harmful
Although they seem harmless, these tests can have negative consequences.
People often receive long lists of foods to avoid, which can lead to:
unnecessary dietary restrictions
anxiety around food
risk of nutritional deficiencies
And perhaps more importantly:the real cause of your complaints is not investigated.
What should you do instead?
If you have complaints such as:
a bloated feeling
abdominal pain
diarrhoea or constipation
suspected food intolerance
then it is better to investigate this together with a registered dietitian or doctor.
With evidence-based methods, it is often possible to look more specifically at the potential cause of your complaints.
Take home message
Food sensitivity tests that measure IgG antibodies, and hair tests, are not scientifically validated for diagnosing food intolerances.
They can lead to unnecessary dietary restrictions, additional stress around food, and wasted money.
If you suspect that food plays a role in your complaints, professional guidance is the most reliable way to find the real cause.