The diet of modern man is rather monotonous and represents a standard set of products and ready meals. At the same time, high-calorie foods are consumed, poor in vitamins and useful substances, saturated with ‘fast’ carbohydrates with a high glycaemic index. Even those who consider their diet to be rational and healthy probably compare it to the average diet – and that’s not quite right. Lots of nutrition advice telling you which foods are ‘good’ and which are ‘bad’ can be seen from the pages of websites and the TV screen. Which one is the right one? One thing is clear here so far: there is something wrong with the modern diet. The number of people suffering from the consequences of their daily menu has increased to epidemic proportions worldwide. Statistics from the World Health Organisation report disappointing figures: over the last ten years, the number of overweight people has risen from 19% to 23%, and these figures continue to rise. Irrational nutrition becomes the cause of many diseases: obesity, diabetes, osteoporosis, pathologies of the cardiovascular system, cancer and many others. This was the reason for the formation of a new science – nutritiology – which studies the role of nutrition in the development of diseases and health maintenance. The composition of any food includes nutrients (from Latin nutritio – nutrition) – inorganic and organic food substances that the body uses to regulate physiological and biochemical functions, tissue and cell renewal, and energy production. Such substances are proteins, fats, carbohydrates, vitamins, minerals and others. Those who unequivocally declare the harm of fats and carbohydrates and directly point to them as the culprits of diseases, do not take into account that they play an important role in human survival. Experts advise not to stigmatise these sources of calories in advance, but to begin with, to understand what are the varieties of harmful and useful carbohydrates, proteins, fats and other nutrients. Also, nutrition affects everyone differently. What seems healthy for one person may be detrimental for another. For example, everyone knows the benefits of milk as a source of calcium, vitamin D and protein, but as we age, many people simply stop digesting it. This condition is called lactase deficiency, which affects a large proportion of the population (for example, almost all Chinese people are lactose intolerant after the age of 30). The human digestive system is individual and adapted only to certain types of food. Yet one thing is true: the more natural the way of eating, the more benefits it brings. This does not mean that you should eat only cereals and raw food, as our distant ancestors did. In fact, you just need to know the capabilities and needs of your body, and then it will be possible to keep the digestive system in tone, so that it will serve without fail for many years.

For many years, the human digestive system has been perceived mechanically: it takes in food, breaks it down, extracts calories and nutrients, and removes the rest from the body. This is an oversimplified understanding, because the digestive system (aka GI tract) is much more complex than a food processing machine. As scientists have found out, the gastrointestinal tract has its own nervous system, it has more immune cells than blood and bone marrow (because it is the first to be exposed to dangerous microorganisms contained in the food consumed). The GI tract is also the largest repository of serotonin: it is where 95% of these signalling molecules from the entire body are found. Serotonin is needed not only for normal GI function, but also for regulating sleep, appetite, pain sensitivity and mood. The digestive system is connected to the brain by bundles of nerves, and this is a two-way communication: hormones and inflammatory signalling molecules produced in the GI tract bring signals to the brain, and hormones created in the brain in turn transmit signals to the cells of the GI tract, determining the nature of their functioning. Therefore, after a meal a person may feel nausea, discomfort or, on the contrary, a sense of satisfaction. It can be said that the sensations of the GI tract will significantly affect the general well-being, including mood, emotions, decisions made. It is known that there are many microorganisms living inside the digestive tract (there are 100,000 times more of them than there are people on Earth). Collectively, they are called the intestinal microbiota. Its components – bacteria, archaea, protists, fungi and viruses – help in digesting food, regulating metabolism, neutralising hazardous substances and strengthening the immune system. Advances in technology have made it possible to accurately identify and characterise such microorganisms: in particular, the large Human Microbiome Project, launched in 2007, has played a significant role in this endeavour to develop a comprehensive understanding of the microbial system and how it contributes to human health and predisposition to disease. To prove the influence of diet on the composition of the gut microbiota, the scientists decided to compare the microflora of one group of children living in a rural setting in Burkina Faso and another group living in an urban setting in Florence. The children of these groups had completely different intestinal microbes: the former were dominated by beneficial bacteria – bacteroidetes (those that help to extract more energy from food), the latter – pathogenic Firmicutes (those that predominate in overweight people). The fact is that children in rural Africa ate natural foods: cereals, vegetables, sometimes chicken, while the diet of Italian children included pasta, pizza, sweet carbonated drinks, crisps, cooked breakfasts and others. The unhealthy intestinal microbiome of western children, formed from such a diet, according to scientists, is very harmful, as it provokes allergic reactions, obesity, type II diabetes, autoimmune diseases, mental disorders and many others. Proponents of low-carbohydrate diets, raw food diets and other trendy trends in nutrition often call for the rejection of certain nutrients in favour of others, to eat less and exercise a lot in order to reduce excess body weight. But human digestion is much more complex. Intestinal microorganisms determine exactly how appetite and energy expenditure will be regulated, how many calories will be stored as fat, and how much inflammation the cells will experience. The gut microbiota is unique to everyone and can produce different physiological and psychological responses.

Currently, the task of researchers is to create the most accurate nutritional recommendations for each specific case based on genetic information, including genetic information. In this regard, there is a need to consider the interaction between a person’s nutrition and his or her genes. This led to the birth of a new science – nutrigenomics, which studies how food and nutrients affect the activity of genes, and helps to determine the early stages of formation of nutrition-related diseases. By knowing one’s genetic profile, a person can take action in advance to protect the body from developing a pathological condition. Personalised medicine is gaining momentum. This, in turn, ensures the growth of personalised diets. Today it is already possible to carry out genetic testing to form a personal diet that will help to improve the health of the body. Thus, genes are able to tell who can, for example, without harm to consume sweets, and who will get the result in the form of obesity or heart attack. To date, scientists have been able to analyse 45 genes that influence the work of internal organs to prepare a healthy eating plan. These are just the first but already successful steps. There are also projects aimed at working with people who are already ill: researchers are tailoring personalised diets to combat diseases such as cystitis and cancer. Personalised diets based on genetic data could be the key to solving many health problems.

Eating disorders can also be associated with psychological disorders in a person – here it is important to investigate psychosomatic causes, because this is the subject of psychologists and psychiatrists. One of such disorders is food addiction, in which a person loses control over the consumption of food, cannot stop, if he/she even wants to do it. The same areas of the brain are activated as in any other addictive disorder. The researchers concluded that people are most often addicted to foods with a high glycaemic load. In addition, high fat content also contributes to the development of the disease. Thus, uncontrolled appetite, food addiction, food disorders against the background of depression and other failures of normal functioning of the body involve not only referral to a specialist, but also correction of lifestyle: setting goals and motivations, formation of a positive attitude, development of a sense of responsibility, self-control, introduction of physical exercise. It is worth saying that to abruptly start eating only vegetables – not only will not be useful, but also will make the body experience the strongest stress. Therefore, it is important to take small steps to a healthier menu. And very soon you will already notice positive changes in your own condition. The benefits of an optimised, balanced and calculated diet will be worth the effort. It is important to take a holistic approach to solving nutritional problems. The exact composition of a healthy diet depends on individual needs, but the basic principles of its formation remain common: it is limiting calories, reducing the use of animal fats and the introduction of vegetable fats, reducing the amount of salts and sugars, the use of fruits and vegetables as snacks. Proper nutrition is the foundation of bodily health and well-being. And this is a direct way to longevity and eternal youth of the organism.