Nutrition is the process by which the body receives the nutrients necessary for the development of physiological activities and ensures the energetic, enzymatic, hormonal substrate necessary to fulfill the main functions: relationship, nutrition, and reproduction.
Nutrition is a component of lifestyle along with physical activity, mental health, and sleep.
Definitions can be given for a healthy lifestyle, but the most important thing is to behave in such a way as to reduce our risk of disease.
Of course, smoking, aggressive behavior, environmental pollution, lack of immunizations, drug use contribute to increasing this risk.
Concerns about maintaining health have existed since antiquity.
The “principle of double perfection” mentioned in the rabbinic writings (the Talmud), in Romans the well-known “Mens Sana in Corpore Sano” expresses the need to maintain a good physical and mental state.
The writings mentioned recommendations about diet, the nutritional value of food, their toxicity.
Dietary concerns are also found in Cornelius’ work “De Arte Medica”
What is the role of nutrition? Why do we eat?
Through food, we ensure the nutrients – proteins, carbohydrates, lipids, minerals, and vitamins.
They play multiple roles:
l Plastic – entering the structure of cell membranes (proteins and lipids)
l Functional – by participating in the synthesis of enzymes, hormones, nucleic acids
l antioxidant (vitamins)
l increase resistance to infections (vitamins)
l participates in the transmission of nerve impulses and the function of the nervous system (vitamins B1, B6)
l maintain the functioning of the bone system (calcium, phosphorus, vitamin D)
l participates in maintaining vision
l prevent cavities.
How much do we eat?
Food is a necessity, but also a pleasure. The pleasant or unpleasant effect of food can act as a stimulus for ingestion or avoidance of food consumption. We usually eat when we are hungry to feel good.
Normally there must be a balance between food intake and energy consumption.
Caloric requirements are individual depending on age, male/female, weight, height, physical activity.
The mechanism for regulating food intake is complex
The triggering factors are represented by the decrease of the level of nutrients (carbohydrates, lipids, proteins) in the blood; release of adipokines (leptin and adiponectin) from adipose tissue; release of pancreatic hormones: insulin, pancreatic polypeptide, amylin with anorexigenic effect (decreases appetite); release of digestive peptides: neutral polypeptide Y, ghrelin that increases hunger, GLP1, oxyntomodulin, cholecystokinin, bombesin that are anorexigenic; thyroid hormones (increase or decrease food intake).
The impulses from the periphery reach the level of the nervous system, in the hypothalamus where there are regulation centers for food intake (arched nucleus and paraventricular nucleus) and its increase or decrease is ordered.
Also, the stimulation of certain areas of the brain (the nucleus assumes) is accompanied by increased consumption of very tasty foods, high in sucrose and fat.
The prefrontal cortex and the limbic system are involved in censorship behavior and self-control of hunger and satiety.
What do we eat?
It is good to have a diet as varied as possible to ensure the caloric needs, but also to respect the proportions between food principles and to ensure the need for vitamins and minerals.
There are foods we should eat daily: whole grains (bread, rice, pasta), vegetables and fruits, milk, yogurt, cheese.
White meat, fish, the egg should be eaten several times a week, and red meat, sweets several times a month. It is good to avoid excessive consumption of chocolate-type sweets, creams, high-calorie fast food, snacks.
It is recommended to avoid the consumption of drinks sweetened with sugar.
Alcohol consumption should not exceed 25 g of pure alcohol in women and 30 g in men.
For food to be organic (organic) it must come from animals raised without antibiotics or growth hormones and pesticides must not be used to grow fruits and vegetables.
To avoid contamination of food with microorganisms, it is good to follow some rules: handwashing, washing all fruits and vegetables before consumption, correct food preparation.
Water can be contaminated with pesticides, lead, mercury, chlorine, microorganisms.
Seafood can be contaminated with mercury resulting from industrial pollution.
It is important to know the stages of food preparation because through processing they undergo changes that cause loss of nutrient content or the appearance of toxic compounds.
The first stage in food processing consists of checking their health status:
l fresh meat has an elastic consistency being covered by a damp, non-sticky film, and the juice is clear
l fresh cow’s milk is white in winter and yellow in summer, homogeneous, without impurities, sweet taste
l the fish must have a pleasant smell
l fresh butter is yellow and homogeneous
l the oil must be clear, yellow, odorless
l the potatoes must be smooth, shiny, and not sprouted
l cans must not have a domed lid
The correct thawing of the meat is done slowly within 3-4 hours. Defrosting in hot water is not recommended.
Wash eggs well with warm water before cooking.
Wash vegetables and fruits before use.
Through heat processing, food undergoes transformations
By frying, toxic and carcinogenic products are formed (acrolein and acrylamides), vitamins are lost
Boiling loses vitamins, so it is recommended to steam under pressure
By preserving the food it is protected from the oxidative action of the environment
Freezing maintains the properties of food, but thawing must be fast if Food is to be cooked hot or slow if eaten raw.
How many meals a day are needed?
The newborn eats on request and can have up to 8 meals a day, the baby has 6-7 meals a day, the small child 3 meals and 2 snacks.
Adults generally have 3 main meals and possibly 2 snacks.