Nutrition Chapter 4 Nutrients: Chemical substances that we consume in the form of food. Nutrients are divided into 2 main categories: A. Energy containing nutrients 1) Carbohydrates 2) Proteins 3) Fats
B. Non-energy containing nutrients 1) Minerals 2) Vitamins 3) Water
A- Energy containing nutrients 1) Carbohydrates - Those are organic compounds which are made up of carbon, hydrogen and oxygen -
Carbohydrates are the main source of energy.
-
The amount of energy given is 17kj/ glucose molecule.
Carbohydrates are divided into 3 main catagories. i- Monosaccharide. -
Simple sugar made up of only ONE molecule.
-
It has the chemical formula of C6H12O6.
-
The most common example is Glucose
-
Other examples are Galactose and Fructose 1
ii- Disaccharide -
Made up of 2 attached together.
-
Maltose = Glucose + glucose
-
Other examples of disaccharides are Sucrose and Lactose
iii-
Polysaccharide
-
Made up of 3 or more glucose molecules attached together
-
Examples of polysaccharides are 1- Starch (plant storage) 2- Glycogen (Animal storage) 3- Cellulose (plant cell walls)
Uses of carbohydrates: -
Carbohydrates are the major source of ENERGY If there is more glucose than needed then it will be converted to glycogen for storage. If our storage units are full and excess glucose is still present then it will be converted into Fats.
2
How to test for Carbohydrates. 1- Testing for Starch: [Indicator used is Iodine (Brown/Yellow)] - Add some iodine (Brown) to an unknown sample of food.
-
Result If the sample changes to a black/blue color = Then starch is present (Positive) If the sample stays brown/yellow = then starch is absent (Negative)
2- Testing for Glucose (Reducing sugar): [Indicator used is Benedict’s solution (Blue)] - Add some Benedict’s solution (blue) to an unknown sample of food. - Place the sample in a water bath at a temperature of 35° C.
-
Result If the sample turns orange/red = then glucose is present (Positive). If the sample remains blue = then glucose is absent (Negative).
3
2) Proteins: - Proteins are organic molecules made up of carbon, hydrogen, oxygen, and nitrogen - The building blocks of proteins are amino acids. - Amino acids are held together by bonds called peptide bonds - A chain that has up to 100 amino acids is called a polypeptide chain - Longer chains of amino acids are called proteins.
Proteins are required for 1- Cell membrane 2- Muscles 3- Collagen (bones and skin) 4- Keratin (hair and nails) 5- Hemoglobin (blood protein) 6- Enzymes 7- Antibodies 8- Insulin 9- Energy How to test for proteins. [Indicator used is Biuret solution (Blue)] -
Add some biurets solution to an unknown sample of food and shake it. Result If the sample turns purple = then proteins are present (Positive). If the sample remains blue = then proteins are absent (Negative). 4
3) Fats (Lipids): -
Fats are organic molecules made up of carbon, hydrogen and oxygen. The building blocks of fats are 3 fatty acids and 1 glycerol.
-
Fats are used for 1- Cell membrane 2- Insulation (Fat under the skin help keeps heat from escaping and therefore keeping the body warm) 3- Buoyancy 4- Energy (Fats provide us with twice as much energy as carbohydrates and proteins)
How to test for Fats [Indicator used is Alcohol] -
Place an unknown sample of food in a test tube. Add a few drops of alcohol and shake it. Pour cold water into the test tube
-
Result If a milky layer forms on top = then Fats are presents
-
If the sample stays clear = then Fats are absent.
5
B- Non-energy containing nutrients. 1) Vitamins: - Although vitamins are organic, they DO NOT supply us with energy. - Vitamins are required for maintaining a healthy body. - The 2 vitamins we are concerned with are Vitamin C ( Also known as Ascorbic Acid) Vitamin D
a- Vitamin C (Ascorbic Acid) It is found in lemon and oranges (citrus fruits). It helps strengthen the immune system. It helps keep the gums healthy. Vitamin C deficiency results in a condition called Scurvy (Bleeding gums).
b- Vitamin D Found in fish oil, liver, milk and eggs. It can be produced in the body when the skin is exposed to sunlight. Vitamin D is needed in the body to help absorb Calcium. The presence of calcium results in the formation of strong bones and teeth. Vitamin D deficiency results in a condition known as Rickets (Soft bones).
6
2) Minerals: Just like vitamins, minerals help your body grow, develop, and stay healthy. Two of the most important minerals are iron and calcium.
(i) Iron - It is necessary to make hemoglobin (The blood protein which carries oxygen). - It is found in green vegetables, red meat, and liver. - Iron deficiency causes anemia – Not enough hemoglobin is made to carry enough oxygen around the body.
(ii) Calcium - It is necessary to maintain strong bones and teeth. - It is found in dairy products. - Calcium deficiency causes rickets – softening of bones.
3) Water: It is essential for metabolic reactions and transport.
4) Fiber - Fibers are made out of cellulose. Therefore, they cannot be digested or absorbed. - They are essential for peristalsis – the contraction and relaxation of the muscles of the digestive system. - Fibers in a diet prevent constipation and bowel cancer. - Fibers are found in fruits and vegetables.
7
Balanced Diet -
It is a diet which contains suitable amounts of all nutrients. The amount of food you eat (and the amount of energy in that food) depend on Age Gender Occupation Health status Physical activity
Malnutrition -
It is a condition in which a person isn’t eating a balanced diet – either too much or too little of particular nutrients.
Types of malnutrition 1- Starvation: - People in this condition do not eat enough food for a long period of time, - The body starts using its stored food for energy. As a result, muscles become weaker and body stops growing properly.
2- Deficiency diseases: - Diseases caused by not taking enough of a specific nutrient, such as Vitamin C deficiency = scurvy Vitamin D deficiency = rickets
3- Obesity: Eating too much food (more than a person’s daily requirement) hence having extra food stored as FAT.
4- Constipation: Consuming insufficient amounts of water or fiber reduces peristalsis. This causes a difficulty in egesting waste materials from the body.
8