Everyone is unique not only in appearance. Ordinary people, not only look differently, but also react differently to food. The adverse reaction of the human organism is caused not by infamous calories, but by substances constituting the food. There are plenty of pills relieving gastrointestinal symptoms, but there is no cure for food. Although the sensitivity to aberrant modern food products is classified as a disorder, it does not necessarily implies a disorder and can be merely a manifestation of the natural diversity in the human population. Many people simply have to avoid some foods and prefer the right foods. There are a few reasons for that. The modern food is not the same as the food used to be eaten by previous generations. The food composition has changed during the last century. The intensive breeding and selection of the commercial traits such as yield, look and profits per hectare also considerably reduced the nutritional value of food. The worldwide genetic diversity of livestock and crops has been gradually but irreversibly impoverished and thereby food sources became increasingly homogenized. Moreover, the commercially available food products are polluted with uncountable, and often toxic, xenobiotics such as synthetic foods additives, hormones, antibiotics, herbicides, pesticides, fungicides or even transgenes. The food industry undermines human health all over the world by promoting inappropriate diets or unsafe foods (Sukhdev et al. 2016).
Any naturally occurring food is composed mostly of extremely diverse biological substances such as proteins, carbohydrates (also called sugars) and fats (lipids). Although they are very diverse, some of those substances can be found in different foods, for example an infamous protein gluten is found in cereals, whereas sugar is abundant in fruits and vegetables. Visually different foods might share the same biological compound and, therefore, can cause the same symptoms. If you exclude only one of such foods, the symptoms will persist until all the foods containing the trigger compound are eliminated from your diet. For instance, bread, pizza and cookies may seem as unrelated foods, but they all contain wheat, which is made of polysaccharides found in other cereals as well. Carbohydrates, a very diverse group of biological sometimes compounds including sweet disaccharides, oligosaccharides and polysaccharides are often blamed for symptoms. A well-known example of an indigestible disaccharide is lactose. Other carbohydrates are believed to promote irritable bowel syndrome.
A food can be included in a food product. A food product is a mixture of different processed foods, natural and synthetic compounds. Food products contain many ingredients that are also found in other products.
In addition to the natural substances, commercially available food products additionally contain numerous chemicals, most of which are not even listed as ingredients. All those mass production leftovers can be disregarded in the food diary records as the food without chemicals is not commercially available. But one should keep in mind that, when it is possible, it is healthier to opt for less toxic food with fewer poisons and carcinogens. Eventually, any food is digested down into carbon dioxide and water, while its indigestible components are excreted. The gut transit time, an important for the food diary parameter, varies from a person to person.