Food and Nutrition

Posted on Sep 7, 2024 in Biology

Theme 2: Food and Nutrition

1. Introduction

It is quite common to confuse the concepts of nutrition and food, yet they are not synonymous. Food consumption is a voluntary process, while nutrition is an involuntary process that occurs as a result of the former.

Food: It is the process by which we take in certain foods and incorporate them into the body.

Food: These are solid or liquid substances that are transformed naturally or ingested by the body.

Nutrients: These are food components that living things use to perform their functions.

Nutrition: Comprises the following processes:

  1. Transformation of food into simpler chemicals.
  2. Absorption of these substances by cells.
  3. Transportation of nutrients to reach the cells.

2. Purpose of Food

Food is essential for life and has a significant influence on health, growth, beauty, and the productivity of the population, and therefore, on the development of society. Most foods, upon digestion, are converted into simple substances that are absorbed by the digestive tract and reach various body cells.

In cells, nutrients have different functions:

1. Energy Function: Some substances are burned to produce energy for the normal functioning of the body. This provides us with enough calories to perform our daily activities. Examples include fats and sugars.

2. Plastic Function: Nutrients participate in the repair of damaged tissue and allow for growth. For example, they help repair a broken bone. Proteins are essential for this function.

3. Regulatory Function: Some nutrients are involved in reactions that occur in the body, such as vitamins and minerals.

3. Composition of Foods

Most foods consist of:

  1. Water/Sanitation
  2. Mineral salts
  3. Organic substances (carbohydrates, proteins, lipids, and vitamins)

Food in its exceptional natural form may be made up of just one of these components (for example, sodium chloride – common salt – NaCl). However, the food industry produces various types of simple foods, such as refined sugar, butter, or olive oil. Nevertheless, it is normal for foods to be complex chemicals, consisting of many substances. Some of these are indispensable (carbohydrates, lipids, proteins, vitamins, minerals, and water) for maintaining the body in a healthy state. Others, like fiber, are not digestible but facilitate the transit of stool through the large intestine and the expulsion of waste products.

4. Nutrition

The following systems in our body are directly involved in the process of nutrition: digestive, circulatory, respiratory, and excretory. They work synchronously, performing the following functions:

§ Gastrointestinal: Through ingestion and grinding, food is incorporated into the body. During digestion, food is transformed into simpler substances (nutrients) that can be absorbed into the blood and eventually reach the cells.

§ Circulatory System: It is responsible for distributing the nutrients from digestion and the oxygen obtained from pulmonary respiration, ensuring they reach the cells of tissues. It also carries organic and inorganic waste from cellular activity (carbon dioxide (CO2), ammonia (NH3), etc.) to be expelled from the body through the excretory system.

§ Respiratory: Responsible for taking in oxygen from the outside through the airway to the lungs. In the lungs, the blood releases carbon dioxide (CO2) and takes in oxygen (O2) for transport throughout the body by the circulatory system. It is also responsible for expelling the CO2 generated by cell activity, as its accumulation in the blood is toxic.

§ Urinary: Responsible for expelling waste products from cellular metabolism, such as urea, which must be eliminated as they are toxic to the human body.

5. The Diet

The fundamental objective of a diet is to establish healthy eating habits that support our vital activities and prevent metabolic disorders and food poisoning.

Therefore, as a first level of information, we should consider what we eat, how much, and how. To answer these questions, we need to know:

  1. The physiological characteristics of each individual.
  2. Their corresponding energy expenditure.

Based on this information, we can establish a set of rules that we call a custom feed ration or diet.

The primary goal of any diet is to meet the body’s nutrient requirements. A balanced diet must meet two requirements:

  1. The total amount of food consumed, and thus the energy received from it, is sufficient to maintain a constant weight within the normal parameters of each individual.
  2. The daily diet is varied and includes suitable proportions of the established food groups.

The World Health Organization (WHO) suggests that a balanced diet consists of:

  • Proteins: Not exceeding 15%.
  • Fat: 30% maximum.
  • Carbohydrates: The rest to complete 100%.

Energy needs of a person are calculated as follows:

  • For school age: 50 Kcal/kg/day.
  • In adulthood: 40 Kcal/kg/day.

Certain types of diets:

§ Mediterranean Diet: Benefits of the Mediterranean diet include:

  1. Prevention against diseases such as diabetes and atherosclerosis.
  2. Helps prevent some cancers, such as colon cancer.
  3. It is beneficial in the fight against obesity and is more economical than other Western diets.

§ Special Diets: Sometimes, food is used to correct a metabolic imbalance in the body (e.g., high blood cholesterol, obesity, constipation). This may involve substantially altering the components of a diet. In other cases, dietary changes are made due to cultural approaches (e.g., vegetarian diet). In both cases, we deviate from the basic principles of balanced diets to create special diets that meet specific objectives.

§ Diets to Lose Weight: Obesity is a condition characterized by body weight exceeding 15% of the ideal weight for a person’s age, sex, and height, resulting from the accumulation of fat in various parts of the body. Its causes can be diverse, but an unbalanced diet is among the most common. A proper diet can help restore nutritional balance in such cases.

§ Vegetarian Diets: These diets often stem from cultural or religious reasons rather than dietary approaches. Vegan diets prohibit the inclusion of any food of animal origin (eggs, butter, cheese, honey, etc.) and even some types of plants (cereals). These diets may not ensure complete nutrition, leading to severe deficiencies of calcium and protein. Vegetarian diets that are not strictly vegan and include milk, eggs, and vegetables are more balanced as they provide the animal protein essential for complete nutrition.