Food, Nutrition and Nutrients Explained

• Food is a substance consumed to sustain life, provide energy, and promote growth.
• Food is usually from plant, animal, or fungal origin and contains essential nutrients.
• Food enables growth by providing substances for new cells, tissues, and organs.
• Food powers biological and chemical reactions needed for activities like moving, growing, and reproducing.
• Food facilitates the replacement of damaged tissues by providing materials for new cells.
• Food protects the body from deficiency diseases associated with a shortage of specific nutrients.
• Nutrition is the process of taking in food and converting it into energy and essential nutrients.
• Nutrients are chemical substances in foods needed for growth, energy, and health.
• The five classes of nutrients include carbohydrates, proteins, lipids, vitamins, minerals, and water.

Macronutrients and Micronutrients

• Carbohydrates, proteins, and fats are required in large quantities and are termed macronutrients.
• Minerals and vitamins are needed in small quantities and are termed micronutrients.
• Vitamins and minerals regulate metabolic activity and aid the use of proteins, fats, and carbohydrates, but do not supply energy.
• Minerals contribute to body structure and skeleton formation.

Carbohydrates

• Carbohydrates provide energy and consist of carbon, oxygen, and hydrogen.
• Green plants produce carbohydrates through photosynthesis, combining carbon dioxide and water using solar energy.
• Starch is abundant in potatoes, bread, maize, rice, and other cereals
• Sugar is found as sucrose (table sugar), in fruits, and in some vegetables.
• One gram of carbohydrate provides approximately 16 kJ of energy.

Fiber

• Unavailable carbohydrates provide dietary fiber, which doesn't serve as an energy source.
• Fiber consists mainly of cellulose from plant cell walls, indigestible by humans.
• Fiber reaches the colon, where bacteria digest some of it to form fatty acids.
• Fiber and bacteria add bulk to colon contents, help recollect water, soften feces, and speed up waste passage
• This reduces constipation promotes colon health, and increases bowel movement, found in vegetables, fruits, and grains.

Types of Carbohydrates

• Monosaccharides are simple sugars like glucose, fructose, and galactose, with the formula C6H12O6.
• Disaccharides combine two simple sugars, such as maltose (glucose + glucose), sucrose (glucose + fructose), and lactose (glucose + galactose), having the formula C12H22O11.
• Polysaccharides form when many simple sugars join together, like cellulose and starch with the formula (C6H10O5)n.

Calories

• Energy from raw materials is measured in calories, where one calorie raises the temperature of 1 gram of water by 1°C.
• Kilogram-calories (Kcal), each equal to 1,000 gram-calories, are commonly used in biology and nutrition.

Fats and Oils (Lipids)

• Lipids are high-energy nutrients yielding 37 kJ of energy per gram.
• Lipids consist of carbon, oxygen, and hydrogen in the body
• Fats, from animal sources, are solid at room temperature, while oils, from plant sources, are liquid.
• Major sources of fat include meat, milk, cheese, butter, and egg yolks.
• Oils are obtained from fruits and seeds like sunflower seeds.
• Lipids form adipose tissue under the skin to reduce heat loss.
• Dietary fats facilitate the absorption of fat-soluble vitamins A, D, E, and K.

Proteins

• Proteins are made of amino acids, which consist of carbon, hydrogen, oxygen, and nitrogen.
• Proteins are key nutrients for body growth and building new cells where the structural part of the cell is composed of protein.
• Dietary sources include meat, fish, eggs, milk, cheese, beans, chickpeas, soybeans, and nuts.

Vitamins

• Vitamins are organic substances needed in small quantities for cell chemical reactions.
• Plants synthesize vitamins, while animals and humans must obtain them from plants or animals.
• Vitamin deficiency can lead to diseases like Vitamin A, E, B1, B2 and C deficiencies.

Minerals

• Minerals are inorganic substances needed in small quantities.
• Major minerals include calcium, iron, phosphorus, and iodine.
• Calcium builds teeth and bones, aids muscle contraction, and helps nerve impulse transmission, which is found in milk, cheese, and others..
• Iron synthesizes hemoglobin and carries oxygen in blood, found in red meat, liver, kidney, eggs, groundnuts, and teff.
• Iodine ensures proper thyroid gland function and is sourced from iodized salt and seafood.
• Phosphorus is required to build bones.

Water

• Body fluids are mainly composed of water.
• Water transports digested food into cells and excretes excess salt and urea from the body.
• Water serves as a solvent and transport medium.

Additional Terms

• Diet refers to the food typically consumed.
• A balanced diet contains all nutrients in correct amounts and proportions.
• Deficiency diseases occur from insufficient intake of a particular nutrient.