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: The process by which we consume external substances and incorporate them into our bodies.

Food: Solid or liquid substances that are either transformed naturally or ingested by the body.

Nutrients: Food components that living organisms use to perform their functions.

Nutrition: Encompasses 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, appearance, and productivity. Most ingested food is converted into simple substances that are absorbed by the digestive tract and transported to various body cells.

Functions of nutrients in cells:

1. Energy Function: Some substances are burned to produce energy for normal bodily functions. This provides us with enough calories for daily activities. Examples include fats and sugars.

2. Plastic Function: These nutrients participate in the repair of damaged tissue and facilitate growth, such as repairing a broken bone. Proteins are a prime example.

3. Regulatory Function: These nutrients are involved in various bodily reactions. Vitamins and minerals play a key role in this function.

3. Composition of Foods

Most foods consist of:

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

While some foods are primarily composed of a single component (e.g., sodium chloride – common salt – NaCl), most are complex chemicals consisting of many substances. Some of these substances, such as carbohydrates, lipids, proteins, vitamins, minerals, and water, are essential for maintaining a healthy body. Others, like fiber, are not digestible but facilitate the movement of stool through the large intestine and the expulsion of waste products.

4. Nutrition

The following systems are directly involved in the process of nutrition:

  • Digestive
  • Circulatory
  • Respiratory
  • Excretory

These systems work synchronously to perform the following functions:

§ Digestive System: Ingestion and grinding incorporate food 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: This system distributes nutrients from digestion and oxygen from pulmonary respiration to the body’s cells. It also carries organic and inorganic waste products from cellular activity (carbon dioxide (CO2), ammonia (NH3), etc.) to the excretory system for expulsion.

§ Respiratory System: This system is responsible for taking in oxygen from the air through the airways to the lungs. In the lungs, the blood releases carbon dioxide (CO2) and absorbs oxygen (O2) for distribution throughout the body by the circulatory system. It also expels the CO2 generated by cellular activity, as its accumulation in the blood is toxic.

§ Urinary System: This system is responsible for expelling waste products such as urea, a byproduct of cellular metabolism, which must be eliminated due to its toxicity.

5. The Diet

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

To achieve this, we need to know:

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

Based on this information, a set of rules, known as a custom feed ration or diet, can be established.

Requirements of a balanced diet:

  1. The total amount of food consumed, and thus the energy derived from it, should be sufficient to maintain a constant weight within the normal parameters of each individual.
  2. The daily diet should be varied and include appropriate proportions of the established food groups.

World Health Organization (WHO) guidelines for a balanced diet:

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

Energy needs of a person:

  • School age: 50 Kcal/kg/day.
  • Adulthood: 40 Kcal/kg/day.

Types of Diets:

§ Mediterranean Diet:

Benefits:

  1. Helps prevent diseases such as diabetes and atherosclerosis.
  2. May help prevent certain cancers, such as colon cancer.
  3. Effective in combating obesity.
  4. More economical than other Western diets.

§ Special Diets:

These diets are designed to correct metabolic imbalances (e.g., high blood cholesterol, obesity, constipation) or address cultural or religious preferences (e.g., vegetarian diets). They may significantly alter the components of a standard diet to meet specific objectives.

§ Weight Loss Diets:

Obesity, a condition characterized by a body weight exceeding 15% of the ideal weight for a person’s age, sex, and height, is often caused by an unbalanced diet. A proper diet can help restore nutritional balance and facilitate weight loss.

§ Vegetarian Diets:

These diets are often adopted for cultural or religious reasons. Vegan diets exclude all animal products (meat, poultry, fish, eggs, dairy, honey) and sometimes even certain plant-based foods (e.g., honey, refined sugar). These restrictive diets may lead to deficiencies in essential nutrients, particularly calcium and protein.

Vegetarian diets that include dairy products and eggs are more balanced and can provide the essential nutrients for complete nutrition.