javeria siddiqui
8 min readDec 8, 2022


As we all eat food, some of these foods are not properly digested by us. In consequence, we suffer from vomiting, diarrhea, headaches, cramps, and belly pain. These symptoms might appear immediately, and sometimes they appear in 12 to 24 hours. Nutritional science calls them “Food intolerances”. In food intolerances, the immune system is not involved; only chemical reactions occur. There are certain limitations for each variety of food. If a person exceeds the limit and eats a lot, they will suffer from food intolerances.

The primary purpose of this article is to inform people about the rapidly expanding health issue of food intolerances. Most of the time, it is not so harmful, but it can interlink with other diseases, including irritable bowel syndrome, anxiety disorders, and asthma.

A person can be intolerant of any food at any time and at any age. Maybe some types of food have not been digested in the body since childhood, or there may have been some sort of enzymatic change in the body due to some disease, thereby making the human body incapable of digesting certain types of food. Predominantly, there are three macronutrients — carbohydrates, proteins, and fat — that are hardest to assimilate. Food intolerances are classified into three primary types.

  1. Toxic Reaction:

A toxic reaction is the result of ingesting toxic substances that cause food poisoning. For instance, viruses, parasites, and chemicals.

2. Metabolic Condition:

Before I get into the metabolic condition, let me explain to you the metabolic reaction — it is the set of different chemical processes that occur in the body to convert food into energy.

In metabolic conditions, abnormal metabolic reactions start due to the deficiency of certain enzymes, such as lactase and carbohydrate malabsorption.

3. Food Chemical Intolerance:

Tremendous amounts of chemicals are used during food processing to enhance its texture, appearance, color, flavor, and shelf life. People unable to metabolize these chemicals experience food chemical intolerance. Symptoms of food chemical intolerance appear after a few days. Food-chemical intolerance-causing substances are mentioned here;

● monosodium glutamate

● Amines

● Salicylates

● Caffeine

● Sulphites

Furthermore food intolerances division lie under these primary types.

6 categories of food to avoid and symptoms of intolerances appears if you eat:


Denoting fermentable oligo-di-mono-saccharides and polyols triggers the symptoms of the gastrointestinal tract, which are included in food intolerances. It can cause intestinal distress, including reflux, bloating, constipation, and abdominal pain. Fermentable oligo-di-monosaccharides and polyols are naturally occurring short-chain carbohydrates that cause problems during digestion.

High FODMAP comprises fructose , lactose, fructans, and galactans. The human body lacks the alpha galactosidase enzyme, so oligo-di-monosaccharides can not be digested in the small intestine.

Oligosaccharides are fermented by bacteria present in the colon. During fermentation, some gases are produced that cause discomfort in the gastrointestinal tract.

Dairy products:

Dairy products, including milk, yogurt, ice cream, and cheese, lead to food intolerances. Milk is composed of different components: water, lactose, protein, fat, and minerals. The two foremost indigestible components in the body are lactose and casein. Casein is subsumed under the category of protein, and it also contributes to the white color of milk.

There are four major constituents in casein: alpha-S1, alpha-S2, beta-casein, and K-casein. Bovine milk (cow) has a higher level of alpha-S1, which forms a firmed curd during digestion when it contacts enzymes and is consequently hard to digest. Additionally, according to the study, casein and gluten possess “cross reactivity,” which insinuates the structure of casein is similar to the structure of gluten. People suffering from celiac disease have an autoimmune response to gluten, and at the time of digestion, when casein enters the stomach, it is treated exactly like gluten.

Most of you know about lactose intolerances, in which a person is unable to digest lactose milk sugar due to a lack of the lactase enzyme, and the undigested lactose then moves towards the large intestine. Large intestinal bacteria counter it to convert them into a more simple form. Anyhow, I’m going to tell you about four more types of lactose intolerance. Isn’t it enthralling? Here are four types;

  1. Primary Lactose Intolerance:

Commonly present in Asian and African regions. Basically, most people are inborn with lactase enzymes, but with the passage of time and aging, production of this enzyme decreases, which leads to lactose intolerances.

2. Secondary Lactose Intolerances:

The aetiology of secondary lactose intolerances is due to prolonged fatal disease, any accident, or surgery that leads to a deficiency of the lactase enzyme in the body. Examples are celiac and inflammatory bowel disorders. However, it is curable if the disease is properly treated.

3. Developmental Lactose Intolerances:

This type is common in premature babies born earlier than 34 weeks because lactase enzymes are produced in late pregnancy.

4. Congenital Lactose Intolerance:

In this case, the deficiency of the lactase enzyme is inherited, which is rarely present. The gene is transferred from parents to children. In congenital lactose intolerance, the baby cannot tolerate breast feeding as well.

✓ Histamine Intolerances:

Histamine is a compound present in food as well as in the human body. Histamine in food is poisonous to the body. Food contains a lot of macro- and micronutrient compounds, including carbohydrates, protein, vitamins, and minerals. Histidine is a type of amino acid present in various foods and drinks. Enteric bacteria attack histidine and produce the enzyme histidine decarboxylase, which breaks histidine into histamine.

Histamine production depends on the temperature at which food is placed, the time, and the amount of protein in the food. Increased amounts of protein make the food more perishable and prone to histamine production.

Normally, the human body can break histamine through the diamine oxidase enzyme, but if a person is suffering from histamine toxicity, they may contain genetic polymorphisms in diamine oxidase that make them unable to break histamine and consequently cause histamine intolerance. According to the estimated data, 1% of the population has histamine intolerance.

Symptoms of histamine intolerance are;

•Itchy skin

•Red eyes




Foods suspected to contain histamine are fermented foods, aged cheese, and citrus fruits. Usually, fermented foods are good for the gut, but due to the presence of lots of microorganisms, they might be problematic for some people, especially those with histamine intolerance. Citrus fruits are supposed to activate the production of histamine in the body, which causes several health issues.

✓ Food Additives:

Food industries frequently use a diverse amount of food additives to intensify the flavor, color, texture, and shelf life of food. Food additives are intentionally incorporated into foods during preparation, manufacturing, and packaging.

Keep in mind that food additives minimally impart nutritive value. The frequent use of food additives leads to different health issues. There are two types of food additives:

a) Natural food additives:

Natural food additives are obtained from natural sources, for example, animals, plants, and minerals. Beet powder obtained from beetroot is used to impart color to food and maintain consistency in food. Corn and soybeans are also some of the most commonly used natural food additives.

b) Synthetic food additives:

Chemically produced through different substances Examples of synthetic food additives are aspartame as an artificial sweetener and tartrazine as a food coloring agent. Synthetic food additives have adverse effects on health. List of some common synthetic food additives are;

1) Carrageenan:

Carrageenan is obtained from red seaweed and used as a thickening agent in food. It has adverse effects on the GI tract.

2) Guar Gum:

Guar plant seed is used to prepare the gum, which imparts thickness to food. Guar gum has negative impacts such as bloating and gas.

3) Citric acid:

Citric acid’s use as a preservative in beverages also enhances the sour taste in food. The most commonly reported cases of citric acid intolerance are abdominal cramps, throat itching sensations, and eczema.

4) Nitrites/ nitrates:

Nitrates are incorporated into processed foods to increase their shelf life, as nitrates have the ability to inhibit the growth of microorganisms. Symptoms of nitrate intolerance include itching and hives.

Caffeine Intolerance:

Caffeine is a naturally occurring substance in cacao plants, tea leaves, guarana, and yerba mate. It is bitter in taste. Being a significant ingredient in the beverage industry, it was exceedingly in demand, but the extraction of natural caffeine was costly. Scientists introduced synthetic caffeine as a substitute for natural caffeine, which is comparatively cheaper and also matches the requirements of the beverage industry.

In 1942, the Nazis introduced the production of synthetic caffeine. Its manufacturing begins with ammonia, which is then transmuted into urea. In addition, urea is mixed with chloroacetic acid to form uracil. Furthermore, uracil is converted into theophylline. At the end, methyl chloride is added to produce methylated theophylline, also recognized as synthetic “caffeine”. Sodium nitrite, sodium carbonate, and acetic acid are used to eliminate the bluish color.

In cases of caffeine intolerance, the liver cannot metabolize it, which consequently disturbs sleep and upsets the stomach. A 200–400 milligram caffeine intake is allowed.

gluten Intolerance:

Gluten is a naturally occurring protein that provides elastic properties in dough. Gluten is made up of glutenin and gliadin. Gluten arouses three possible diseases, such as non-Celiac gluten sensitivity, wheat allergy, and celiac disease.

Major symptoms are:

Improper ingestion of wheat causes stomach pain. Approximately 83% of gluten intolerance cases go through stomach pain. Another symptom is bloating, in which gas fills the stomach. Brain fog is a situation in which a patient is not able to think properly, also called absentmindedness or mental confusion. Gluten intolerance increases the risk of anxiety and dispersion.

Conclusion, we should eat food according to our body metabolism. Otherwise, careless eating can initiate many diseases. Hopefully my article snuff off perplexity related to food intolerance.



javeria siddiqui

Nutritionist / Food technologist