Nutrients are split into two main groups, the macronutrients which contains carbohydrates, fats and protein and the micronutrients which contains vitamins and minerals. These split groups are based on the amounts of a nutrient needed

Nutrition assignment 1

Nutrients are the chemical substances which we obtain from food. There are many different nutrients and they all provide the body with different things such as energy, structural materials, regulating agents to support body growth, maintenance and repair of the body’s tissues.

Nutrients are split into two main groups, the macronutrients which contains carbohydrates, fats and protein and the micronutrients which contains vitamins and minerals. These split groups are based on the amounts of a nutrient needed in a person’s daily diet. Therefore, we should eat more carbohydrates, fats and proteins each day than vitamins and minerals.

Carbohydrates

Carbohydrates are composed of composed of carbon, hydrogen and oxygen to form compounds. Carbohydrates have a general molecular formula of CH O, this means that for every carbon and oxygen atom there will be twice as many hydrogen atoms.

Carbohydrates are made up of sugar molecules which are classed into different groups depending on how many sugars the carbohydrate contains. There are monosaccharides, which is made up of one sugar, disaccharides which consist of two sugars and there are polysaccharides which consists of many sugars.

Monosaccharides and disaccharides are called ‘simple carbohydrates’ as they taste sweet and dissolve in water. Simple sugars enter the bloodstream soon after eating. Polysaccharides are called ‘complex carbohydrates’ as they do not taste sweet and will not dissolve in water. Polysaccharides take longer to break down than simple sugars and therefore glucose is released into the bloodstream at a much slower rate.

Monosaccharides consist of three carbohydrates and although they all have the same molecular formula of C H O , they are different because of how there atoms are arranged, because these carbohydrates contain six carbon atoms they are called hexose sugars. They are:

Glucose - this is a ‘blood carbohydrate the immediate source of energy for energy production.

Galactose - this is a carbohydrate found in milk and yogurt

Fructose – this is a carbohydrate found in honey and fruits

Galactose and fructose are converted into glucose in the liver. The glucose can then be used for energy production.

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Two monosaccharides can be linked together to form a disaccharide. There are three disaccharides which are:

Sucrose – this is a common sugar made from the linking of glucose and fructose.

Lactose – this is a major carbohydrate in milk made from the linking of glucose and galactose.

Maltose – this is a product of starch digestion made from linking glucose to glucose

This process is called a condensation reaction of linking two monosaccharides results in the loss of a molecule of water (H O), therefore the molecular formula of each of the disaccharides is ...

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Two monosaccharides can be linked together to form a disaccharide. There are three disaccharides which are:

Sucrose – this is a common sugar made from the linking of glucose and fructose.

Lactose – this is a major carbohydrate in milk made from the linking of glucose and galactose.

Maltose – this is a product of starch digestion made from linking glucose to glucose

This process is called a condensation reaction of linking two monosaccharides results in the loss of a molecule of water (H O), therefore the molecular formula of each of the disaccharides is C H O .

Starch is a type of polysaccharide, it is made up of lots of glucose molecules linked together.

Fibre is another type of polysaccharide, it is the part of a plant which is resistant to the body’s digestive enzymes. As a result of this only a small amount of fibre is digested, with the majority moving through the gastrointestinal tract and finishing up in the stool. The main benefits of eating fibre are that it helps to retain water, which results in softer and bulkier stools that prevent constipation and haemorrhoids. Research shows that a high-fibre diet can reduce the risk of colon cancer. Fibre can be found in fruits, vegetables and grains.

The main role of carbohydrates is to provide energy for exercise. Once a carbohydrate has been digested, it will be used as an energy source or turned into glycogen by the liver and stored in the liver or skeletal muscle.

The minimum recommended daily intake of carbohydrate is at least 50% of total kilocalories consumed should come from complex carbohydrate sources. However, if a person eats too much carbohydrate then the excess is turned into fat and stored in fat stores.

Fats

Fats are made up of carbon, hydrogen and oxygen molecules, as are carbohydrates; however fats contain more oxygen atoms in each molecule than carbohydrate molecules.

The building blocks of fat are fatty acids and glycerol.

Fatty acids can be divided into:

Saturated fatty acids
Monounsaturated fatty acids
Polyunsaturated fatty acids

A fatty acid is made up of carbon atoms with an acid group (COOH) at one end and a methyl group (CH ) at the other. The structure of the chains of fatty acids attached to the glycerol molecule will show whether the fat is classed as saturated, monounsaturated or polyunsaturated.

Saturated fatty acids are loaded with hydrogen so the molecule has no double bonds between carbon atoms. These fats are solid at room temperature and are usually from animal sources. It is recommended a person should have a maximum of daily kilocalories coming from this type of fat.

If some of the hydrogen atoms are missing and have been replaced by a double bond between the carbon atoms, the fatty acid is called unsaturated. If there is one double bond, the fatty acid is a monounsaturated fatty acid. It is recommended a person has a maximum of 12% daily kilocalories coming from this fat.

If there is more than one double bond, then the fatty acid is known as polyunsaturated. It is recommended that a person has a maximum of 10% of daily kilocalories coming from this type of fat.

There are essential fatty acids which must be incorporated into the diet. These fatty acids are linoleic and linolenic acid.

The richest sources of linolenic acid include seed oils, nuts, meat from grass-fed animals and green, leafy vegetables. Linoleic acids is found in fish oils and also in the flesh of oily like mackerel, salmon, kippers, herring, trout and sardines. If these acids are not eaten the person is in danger of suffering from grown retardation, reproduction failure, skin lesions, kidney and liver disorders and subtle neurological and vision problems.

Cholesterol is a fat which is an essential part of the body; it is found in cell membranes and several hormones. Some cholesterol comes from our diet but mostly it is produced in the liver from saturated fats. If a person is suffering from obesity, does not take part in exercise or eats a large amount of fatty acids cholesterol levels can become increased.

Fat provides a concentrated source of energy. It stores fat soluble vitamins A, D, E, and K. Fat is very important in the formation of cell membranes nerve tissue. It provides a reserve of energy and helps to insulate the body against extreme temperatures. Stored fat also helps to cushion impact by protecting internal organs against shock.

The recommended daily intake of fat is no more than 30% of total kilocalories. Only 10% of daily kilocalories should come from fat and dietary cholesterol should be limited to 300 mg or less per day.

Protein

The amount of protein in each food varies, the main sources include meat, fish, eggs, milk, cheese, nuts and pulses. Two-thirds of the average intake is obtained from animal sources, such as meat, fish, eggs and some dairy products. Some is also obtained from cereal products, nuts and pulses.

Protein consists of carbon, hydrogen, oxygen and nitrogen. A protein is made up of amino acids. Every amino acid contains an amino group (NH ), an acid group (COOH), a hydrogen atom (H), and a distinctive side group all attached to a central carbon atom.

There are nine Essential amino acids (EAA) that the body is unable to make in sufficient quantities, therefore they must be obtained from food.

The Non-essential amino acids (NEAA) can synthesise from nitrogen, carbohydrates and fat.

The main role of protein in the body is to act as building material. Proteins are needed for the manufacture and repair of most body structures. Enzymes are also made of proteins and are need to facilitate chemical reactions in the body. Some hormones are made up of protein for example, insulin. Antibodies that work to protect against disease are made up of protein. Proteins are also used to help maintain the volume and composition of fluids; this helps to maintain the body’s pH levels by acting like buffers; which help with the transport of lipids, vitamins, minerals and oxygen around the body; in cases of starvation this can be used as an energy source to provide a fuel for the body.

The recommended daily intake of protein is 0.8 per kilogram of body weight, or around 15% in total kilocalories. Protein needs are higher for children and many athletes.

Vitamins

These are organic substances required by the body in small amounts. The body is unable to make vitamins for its overall needs, therefore they must be supplied regularly by the diet.

Vitamins are not related chemically and differ in their physiological effects they have. As a vitamin was discovered it became identified by a letter. Many vitamins consist of several closely related compounds or very similar physiological properties.

Vitamins can be sub divided into:

Water soluble – C and B
Fat soluble – A, D, K and E

Water soluble vitamins can be stored in the body and therefore have to be consumed on a regular basis. If excess quantities of these vitamins are consumed they will be excreted by the body in urine. Fat soluble vitamins are stored in the body’s fat, therefore it is not necessary to consume these on such a regular basis. It is possible to overdose on fat soluble vitamins, this can be detrimental to health.

Different amounts of each vitamins are required – referred to as the recommended daily intake (RDI).

Vitamin A – The main function of this vitamin is to help maintain good vision, healthy skin, hair and mucous membranes and also to serve as an antioxidant. It is also needed for proper tooth and bone development. This vitamin can be found in liver, mackerel and milk products.

RDI – 5000 international units

Betacarotene – This performs a similar function to vitamin A and is found in plants. When there is a shortage of vitamin A in the diet it is used in the place of vitamin A. However, whereas vitamin A is a minor anti oxidant, betacarotene is a super antioxidant. Betacarotene can be found in sweet potatoes, carrots, cantaloupe, spinach and other dark green leafy vegetables. It you have a deficiency in this vitamin it will be shown in the form of night blindness, impaired growth and dried skin.

RDI – 5 to 15 mg or 10 000 to 25 000 international united

B Vitamins are different to the other types although they are not chemical related they often occur in the same food. Their main function is to aid in metabolism of food.

Vitamin B-1 (thiamine) – This vitamin helps convert food to energy. Aids the nervous and cardiovascular system. It can be found in rice bran, pork, beef, peas, beans, wheat germ, oatmeal and soy beans.

RDI – 1.5 mg

Vitamin B-2 (riboflavin) – This vitamin aids the body in growth and reproduction. Helps to metabolise fats, carbohydrates and proteins and promotes healthy skin and nails. It can be found in milk, liver, yeast, cheese, leafy green vegetables, fish and eggs.

RDI – 1.7 mg

Vitamin B-3 (niacin) – This helps to keep the nervous system balanced and is important for the synthesis of sex hormones, thyroxine, cortisone and insulin. This can be found in poultry, fish peanuts, marmite, rice bran and wheat germ.