Human Nutrition: Micronutrients

Human Nutrition

By Naomi Keddy

What are micronutrients?

Micronutrients are the nutrients that are required in small amounts in the body and they are vitamins, minerals and water.

What are vitamins?

Vitamins are complex carbon-based substances that cannot be made in the body. They are only needed in very small amounts. Vitamins are divided into two groups fat-soluble vitamins and water-soluble vitamins. Fat-soluble vitamins are vitamins that are soluble in fats but insoluble in water. Fat soluble vitamins are stored in body fat and can build up to toxic level, it too many vitamin supplements are taken. Water-soluble vitamins are vitamins that are  soluble in water but insoluble in fat. Water-soluble vitamins are not stored in the body therefore must eaten everyday. An example of a water-soluble vitamin is vitamin C ( absorbic acid) The metabolic role vitamin C, forms connective tissue, good for bones and teeth, helps healing and the immune system. The lack of Vitamin C may cause deficiencies such as scruvy. bad teeth and gums. Sources of vitamin C is fruit and vegetables. Vitamin D is an example of a fat-soluble. The metabolic role of vitamin D help absorbs calcium for bones and teeth. The lack of vitamin D may cause deficiencies such as rickets in chidren, and osteomalacia in adults. the sources of vitamin D is liver, fish oils, milk and sunlight.

Fig.1 Rickets

What are minerals?

Minerals elements are required in very small amounts. Minerals are essential for good health. There are many minerals in food, but the main minerals that most people seem to be lacking in is calcium and iron. Calcium is a mineral that is made for the human bones and teeth, it makes the harder and stronger. A good source of calcium comes from milk, cheese, yoghurt and hard water. Calcium links in with Vitamin D, Vitamin D helps absorb calcium. The lack of Calcium in the diet may cause deficiencies such as rickets and osteoporosis. Iron is a mineral that is necessary for the formation haemoglobin of red blood cells, which are used to transport oxygen throughout the body. A good source of iron comes from offal, red meat and green vegetables. The lack of iron in the diet may cause the deficiency of anaemia. Anaemia is caused by the lack of iron in the diet.

Fig.2 Red blood cells that lack Iron

What is water?

Water is a compound of the elements hydrogen and oxygen. The properties of is colourless, odourless and tasteless. Boiling point is at 100ｰc and freezing point is at 0ｰc. Water is essential for life. About 70% of the body is made up of water. The body loses about two liltres of water a day.  A good source of water is a tap or fruit and vegetables. Water is essential for part of all body tissues, major parts of all body fluids, for metabolic reactions to take place and good for transporting important substances. Chemical reactions that water is needed for are photosynthesis, respiration and digestion. Water is a good solvent which allows chemical reactions to take place.

Fig.3 Water

Human Nutrition: Macronutrients

Human Nutrition 

By Naomi Keddy

Why Do Organisms need Food?

Well Organisms need food to maintain metabolism and the continuity of life for all living things. We need to maintain metabolism to maintain homeostasis. We need nutrients to carry out metabolic reactions, as a source of energy and for growth and repair. Nutrition is the study of food, its composition, structure, properties. amounts required and its effects on the body.

What are Macronutrients? 

Macronutrients are the nutrients that are required in large amount in the body and they are Protein, Carbohydrates and Lipids.

What is protein? 

Fig.1 Complex structure of protein

Protein is composed of the elements Carbon, Hydrogen, Oxygen and Nitrogen. Protein is the only nutrient that contains Nitrogen, which is essential for growth in the body. Sometimes protein contains smaller amounts of sulfur, phosphorus and other elements. The basic structure of protein is a build up with amino acids. Peptide bonds are formed when amino acids join together. In this reaction a H2o molecule is lost. The reserve of this reaction is called hydrolysis and it involves the addition of water and enzyme action and this occurs in digestion. There are two sources of protein. Protein that comes from animals and protein that comes from plants. Examples of plant source protein are soya beans, peas and beans. Examples of animal source protein are Chicken, milk, eggs and meat. Structural role of protein is to form structures such as hair, nails and muscles. 

Denaturation  is the unfolding of the protein chain resulting in an irreversible change in shape and the lost of its function. 

Deamination is using protein as a source of energy to control reactions. Excess protein that is not required for growth and repair is deaminated in the liver. An Excess amount of Nitrogen in the body can be toxic the body so that is why excess amount of protein has to be deaminated in the liver. Metabolic role of protein in the body is is used by enzymes to control reactions. 

Fig.2 Biuret test

The laboratory test for protein is the biuret test. If Protein is present it would change to a purple colour and if absent it would result in a blue colour.

What are Carbohydrates?

Fig.3 Structure of Carbohydrate

Carbohydrates are composed of the elements Carbon, Hydrogen and Oxygen. Carbohydrates are mainly found in plant foods. Plants makes their own food from a process call photosynthesis resulting in the production of glucose which is a carbohydrate. Carbohydrates are really good in the diet because they are a slow releasing energy. Carbohydrates are made up of sugar units. There are three types of carbohydrates which are broken into how many sugar units. 

Monosaccharide is one sugar unit. e.g Glucose and fructose. 

Disaccharide is two sugar units. e.g sucrose and maltose. 

Polysaccharide is many sugar units. e.g Starch and glycogen. Carbohydrates carry out several functions such as heat and energy to the body; they are stored as fat to the body. Fibre is good in the diet, because it is a substance that is plentiful in the outside layers of fruit and vegetables and the husks of grains. It is not digested or absorbed by the body but moves quickly through the small intestine and it is excreted out as waste. This helps prevent bowel disease. Sources of carbohydrates are bread, potatoes, rice and flour. 

The laboratory test for carbohydrates is Benedict's test (For Reducing Sugar) and Iodine test (Test for Starch). 

Fig.4 Benedict's test

 The Benedict's test, if sugar is present it would result in a brick red colour and it is negative it would result in a blue colour. 

The iodine test, if starch is present it would change to a blue-black colour and if absent it would result in a red-yellow colour.

Fig.5 Iodine test

                 

                                                                

What are Lipids?

Lipids are fats and oils that are composed of the elements Carbon, Hydrogen and Oxygen. Fats are solid at room temperature and oils are liquid at room temperature. Fats are divided into two types: Saturated fats and unsaturated fats. Saturated fats are fats that come from an animal . Saturated fats are known as the bad kind of fats. Unsaturated fats are fats that come from plant sources. 

The structure of lipids is glycerol and three fatty acid which is called triglyceride. 

Fig.6 Triglyceride

Glycerol and two fatty acids and a phosphate  are called phospholipid. 

Fig.7 Phospholipid

The structural role of lipids is heat and energy and protection of organs. The overuse of lipids may lead to stokes, heart disease and obesity. The metabolic role of lipid is to be broken down in respiration to release energy. The laboratory test for lipids is using brown paper, if it is a lipid it would stain a wet look and it isn't it won't be visible.