It’s not an allergy, but some foods might not quite agree with you. Wondered why, after lunch, you sometimes feel sluggish? Have you ever had a splitting headache after a meal, or found your eyes watering? It could be food intolerance.

Food intolerance is most often mistaken for allergy, but the doctor will tell you that it is something quite different. While foods you are allergic to trigger responses in the immune system, food intolerance affects metabolism or digestion. Diarrhoea, indigestion and bloating are common symptoms.

Although there are no India-specific studies, globally, the incidence of food intolerance is high; nearly 45% of the population is affected at any time.

Bangalore now has a sample collection centre to test food intolerance. “We receive a large number of samples everyday, from across the country. We have been receiving a sizable number of food intolerance test requests from Bangalore. We have performed nearly 1,000 tests already, in seven months,” said Dr Sanjeev K Chaudhry, chief executive officer, Super Religare Laboratories Limited.

Food intolerance is diagnosed by measuring the Immunoglobulin G (IgG) antibodies that are involved in what is called the ‘secondary immune response’. The tests conducted to ascertain the condition check over 200 foods in an individual’s blood specimen.

Dr Chaudhry explained that an allergy to peanuts or milk, for example, is characterised by an immediate and often severe reaction in response to ingestion. This is associated with the production of IgE antibodies, which trigger the immune response in mammals. Food intolerance causes unpleasant symptoms, but is not life-threatening.

“Less than 2% of the Indian population develops food allergies. Most cases of food allergies are actually instances of food intolerance,” said Jyothi Prasad, chief dietician, Manipal Hospital.

Tragic life events - acute illness or painful separation - could set off stress that results in intolerance of foods associated with those events.

Even such common items in the diet, like wheat and rice could trigger intolerance insome people. There are other less common dietary items too that cause food intolerance - vanilla, bakers’ yeast, casein.

Food intolerance has no known cure. There are no medicines to deal with it, and the condition is best managed by avoiding foods that trigger it, opine city doctors.

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Soumita Majumdar / Reuters