Macro and micronutrients
The components of food can be classified into two major groups based on the nutrients that persons need to consume on a daily basis for their normal body functions. They are macro-nutrients and micro-nutrients.
Macronutrients are nutrients required and consumed in large amount on a daily basis. This includes proteins, carbohydrates, lipids (fats and oils) and water.
Micronutrients are essential nutrients required by the body and consumed by people in a small amount. This includes vitamins and minerals. Even though micronutrients are needed in a small amount, if they are not supplied to our body in the amount they are required, they can cause deficiency disease.
A. Macronutrients
I. Protein
Protein is an organic compound containing oxygen, nitrogen, iron, phosphorus, sulphur and cobalt with different proportion. It was the first substances to be recognised as a vital part of the living tissue. Hence, it is named protein meaning "of first importance".
Proteins are the second most abundant component of the body (about half of our body's dry weight is protein) distributed in the muscles, bones and cartilages, skin, tissues and body fluids.
Amino acids are the basic structural units of protein, or they are the building blocks of protein. There are 20 recognised amino acids. Amino acids which can't be synthesised in the body and must be supplied from food are none dispensable or essential amino acid. Amino-acids that could be synthesised by the body are called none essential or dispensable amino- acid.
The primary functions of protein are body building &, maintenance of tissue for growth. It is especially important for children, teens and pregnant women. Pregnant women need protein to build their bodies and that of the babies and placentas, to make extra blood and for fat storage.
Breastfeeding mothers need protein to make breast milk. It is also important for enzymes, antibody and hormone synthesis. It yields 4 kcal/gm. Of protein Based on the nutritional value or its essential amino-acid content, protein is classified as:
- Complete protein (First class protein or animal source protein) contains all the essential amino acids in the proportion that is required to support growth and maintain tissues.
- Incomplete protein (Second class protein or protein of plant origin) contains proteins that do not contain all the essential amino-acids in the proportion required by the body.
Animal foods contain better /good quality of protein than plants source of foods. However, even though plant proteins are usually not as good for body-building as animal proteins, they can become more effective nutritionally when both are mixed with each other.
Food sources of proteins:
- Animal sources of proteins: meats, chicken, eggs, milk, fish, cheese.
- Plant sources of proteins: beans, Legumes, cereals, ground nuts, lentils, soybeans.
(Note: Combining legumes & cereals provide a better quality of protein).
II. Carbohydrates
Carbohydrates are organic molecules that are made up of elements of carbon, hydrogen and oxygen. Carbohydrates are the principal source of energy (calories), nearly 65 % of energy for our body is supplied from carbohydrate. They supplied us with 4 kcal / gm of carbohydrate.
This energy is usually obtained in the form of glucose which all tissues and cells in our body readily use. Hence they are needed in large amount by the body. Carbohydrates are classified into different categories based on the number of single carbohydrate unit they contain and their functions in the body.
They are classified as:
- Monosaccharide or free sugar: carbohydrate containing single sugar molecule. E.g. Glucose (dextrose or grape sugar), galactose (milk sugar), fructose (fruit sugar), mannose and ribose. Glucose is the major fuel source that is oxidised by cells for energy.
- Disaccharides or carbohydrates containing two glucose molecule. E.g.. Maltose (malt sugar), lactose (milk sugar), sucrose (fruit sugar). When disaccharides are digested and hydrolyzed, they produce simple sugar (glucose, galactose and fructose).
- Polysaccharides or complex carbohydrates: Starch, glycogen (animal starch) and cellulose are important in nutrition. Cellulose is also called dietary fibre or roughage. For example, Kocho/enset.
Fibre is a complex carbohydrate that is not digested and passes through the alimentary canal nearly unchanged, and this prevents constipation /compacted stool/ by making the faces soft and bulky. It makes the food bulky, bigger and helps a person who is overweight to reduce weight by reducing the nutrient absorption from the intestine and amount of nutrient intake.
As a health extension worker, you can educate a pregnant mother to take fibre-rich diet to prevent constipation as it could be among the commonly occurring miner pregnancy related disorder. Fibre foods are a way for obese people to help losing weight.
Food source of carbohydrates or CHO:
The main source of carbohydrates is bread wheat, potatoes of all kind, maize, rice, cassava shiro , pasta macaroni kocho, banana, sweets, sugar cane, sweet fruits and honey. Other sources of foods like vegetable beans, nuts, and seeds contain a lesser amount of carbohydrates.
III. Lipids (Fats and Oils)
They are a group of organic compounds like carbohydrate contains C, H, & 0, and some have phosphorus and nitrogen. Lipids are commonly referred to as fats. Fats and oils are concentrated sources of energy that yield 9 kcal per gm of fat and so are important nutrients for young children who need a lot of energy-rich food.
The building blocks of lipid are fatty acids and glycerol, or they are the end digestion product of lipids, fats and oils. Fats can also make meals more tasty and satisfying.
Nutritionally, lipids are classified into two main groups by their degree of saturation, i.e. .saturated fatty acids and unsaturated fatty acids. Knowledge about the classification is important to enable you to advise your community about which fats can be consumed with less risk to people‘s health
Saturated fatty acids are usually solid at cool room temperature and are found mostly in animal foods (butter, meat). Eating too much saturated fat is not good for health as it can cause health and blood vessels problems.
Unsaturated fatty acids are usually liquid at room temperature, and thus types of fats are healthy fats because they contain no animal fat. Thus types of fats are found from plant source of food.
Food source of lipids:
- Animal source: meat, chicken, milk products, butter, creams, fats, cheese fish, egg.
- Plant source: avocado, ground nuts, coconut, vegetable oil, nuts, margarine and soya bean.
IV. Water
It is the most abundant constituents of the body, comprising roughly two third (60%) of body weight. Every part of the body contains large amounts of water. A person can stay alive without food for a few weeks, but it is not possible to stay without water for more than a few days. The average daily requirement of water for an adult is vary from 2 - 3 litres. Water is essential for life, and it is required for some reasons:
- To make cells and body fluids (blood, digestive juices, breast milk, etc.
- For regulation of body temperature (cooling the body).
- To wash out of body wastes /excreted in the form of urine.
- Keeping different body organs wet and health.
- As a carrier, it aids digestion, absorption, transportation and excretion of nutrients.
- Provides mechanical functions (lubrication of joints and visceral organs).
- Useful for catering (preparation of food)- reduce foodborne diseases.
- The distribution and proportion of water in different parts of the body.
The body’s water balance may be affected by vomiting, bleeding, burns, or diarrhoea