Human Nutrition I

A GREAT STARTING POINT IN NUTRITION

Nutrition is in the spotlight as a way to support people to live happy, healthy lives. 

There are many aspects to nutrition and how it impacts health:

This distance learning course is your first step toward an in depth understanding of human nutrition, covering:

Lesson Structure

There are 9 lessons in this course:

1. Introduction to Nutrition
   • Important factors in nutrition
   • Ingredients and cooking methods
   • Understanding eating
   • Major food groups
   • Food allergies and Intolerance introduction
2. The Digestive System
   • The Alimentary Canal- Muscular Structures
   • Accessory Digestive Organs
   • Digestive Tract Linings
3. Absorption and Enzymes
   • Physical and Mechanical breakdown
   • Understanding biochemical breakdown
   • Biological breakdown
   • Digestive Hormones
   • Digestive Enzymes
   • Absorption - anatomical adaptations for absorption
   • Absorption (general)
   • Detoxification mechanisms
   • The Urinary System
   • Physiology of the urinary system
   • Skin and sweat glands
4. Energy Value of Foods
   • The science of nutrition
   • Diet
   • Energy Value in Foods
   • Nutrients
   • Energy Production
   • Basal Metabolic Rate
5. Carbohydrates and Fats
   • Types of Carbohydrates - Monosaccharides, Oligosaccharides and Polysaccharides
   • Carbohydrates in the diet
   • Carbohydrates in the body
   • Alcohol
   • Fats and fat biochemistry
   • Fats in the diet
   • Fats in the body
6. Proteins
   • Uses in the body
   • Recommended protein intakes
   • Grains
   • Vegetables
   • Nuts and Seeds
   • Beef, Poultry and Fish (meat structure)
   • Meat Quality
   • Eggs and Dairy
   • Proteins in the diet
   • Proteins in the body
7. Vitamins and Minerals
   • The Recommended Daily Allowance
   • The Dietary Reference Intake
   • Summary of Vitamins
   • Fat soluble vitamins
   • Water soluble vitamins
   • Common minerals
   • Inorganic elements
   • The Calcium Debate
8. Water
   • Water in the body (function)
   • Water retention
   • Water loss and chronic dehydration
9. Nutrient Disorders
   • Selected digestive system disorders
   • Vomiting
   • Peptic ulcer
   • Jaundice
   • Lactose intolerance
   • Haemorrhoids
   • Cirrhosis
   • Allergies
   • Cholesterol, heart disease and atherosclerosis
   • Bowel Cancer
   • Problems with nutrition

Each lesson culminates in an assignment which is submitted to the school, marked by the school's tutors and returned to you with any relevant suggestions, comments, and if necessary, extra reading.

Aims

• Explain the role of different food types in human health.
• Explain the physiology of digestive processes.
• Recommend appropriate intake of vitamins.
• Recommend appropriate intake of minerals.
• Recommend appropriate food intake to meet an individual's energy needs.
• Recommend appropriate carbohydrate intake.
• Recommend appropriate fat intake.
• Recommend appropriate protein intake.
• Recommend appropriate water intake in different situations.
• Recognise signs and symptoms of the major nutrient disorders.

What You Will Do

• Distinguish between nutrition terms including: food, nutrition and diet
• Distinguish between characteristics and explain the significance of all major food groups,
• Label on unlabelled illustrations, parts of the digestive system and clearly explain their structure and function
• Distinguish between digestion and absorption of food and explain how different hormones control the digestive process, including: Gastrin, Gastric Inhibitory Peptide, Secretin and Cholecystokinin.
• Explain the meaning of basal metabolic rate (BMR) and describe how the intake of different types of food may affect metabolic rate.
• Explain how different factors other than food intake can affect digestion, including stress and disease and explain possible implications of mismatching food intake to individual's energy needs, through over or under intake of energy requirements.
• Develop guidelines to determining appropriate carbohydrate intake, in accordance with an individuals specific requirements.
• Distinguish between saturated and unsaturated fats in the diet of a specific person.
• Explain the role of fat in the body, including an explanation of different physiological processes involving fat. Distinguish between saturated and unsaturated fats.
• Explain the role of protein in the body, including examples of different physiological processes involving protein and explain factors which affect the bodies demand for protein.
• List different sources for each of several different minerals considered essential to human health and explain the role of different minerals in the body. Consider the relative values of different sources of minerals in your own diet, to determine minerals which may be supplied in inappropriate quantities.
• Distinguish between sources of different types of vitamins which are important to human health, including:Retinol, Vitamin D, Vitamin E, Vitamin K, Ascorbic acid, Thiamine, Riboflavin, Nicotinamide, Pyridoxine, Pantothenic, acid, Biotin, Cyanocobalamin, Folacin.
• Explain the proliferation of vitamin supplement usage in modern society and describe symptoms of five different vitamin disorders including deficiencies and toxicities.
• Explain the role of water in the body, for different physiological processes and list factors which affect the bodies requirement for water. Also, explain the physiology of dehydration, at different levels.
• Distinguish between the signs and symptoms of forty common problems associated with nutritional disorders, including: deficiencies, sensitivities and diseases. Also look at different techniques used by health practitioners for determining food/nutrition disorders.
• Explain the importance of obtaining a recommendation from a medical practitioner, when a nutritional disorder is suspected and the significance of obtaining a "second opinion", when diagnosing nutrient disorders.

Is a toned body a healthy body?

The answer is a resounding 'maybe'. It is common to associate a healthy body with strong, toned muscles. Even without an agreed definition of 'healthy' and 'toned' it may be enough to remember that musculature is only part of what makes up highly complex, interrelated processes that effect optimised functionality.

Protein is often touted as a 'muscle building' nutrient and for good reason. In isolation though, this statement could be misleading as there are many processes involved in repairing and building muscle. Protein also has a range of other important health giving roles in the human body relating to the immune system, hormone production, enzyme function and energy. The contribution to health of any nutrient should be understood in the context of the bigger picture.

What are Proteins?

Proteins are very complex substances which like carbohydrates and fats contain hydrogen, oxygen and carbon, however they also contain a fourth element, nitrogen. Proteins are large molecules made up of different combinations of smaller units called amino acids. Different proteins are different combinations of different amino acids.

The body needs eight "essential" different amino acids throughout all stages of life. They are:

•  Tryptophan
  
  
•  Methionine
  
  
•  Valine
  
  
•  Threonine
  
  
•  Phenylalanine
  
  
•  Leucine
  
  
•  Isoleucine
  
  
•  Lysine

As well as the standard four chemical elements, many proteins also contain sulphur and some phosphorus. Every cell in the body is partly composed of proteins. Protein is a structural material required for growth and repair and replacement of damaged tissues. Proteins are involved in the regulation of numerous cellular processes and are also the end product of many. They are crucial for vital processes such as glandular secretions, enzymatic and hormonal actions. As a result of proteins requirement in numerous vital functions, protein is the least favoured energy source and is only used as such when absolutely required.

Plants manufacture their own protein from their basic components, carbon, hydrogen, oxygen and nitrogen, but humans and other animals cannot do this. People and animals must obtain theirs from plant foods. Humans and other carnivorous animals can obtain their protein supply eating animals that in turn get their protein from plants.

Proteins consist of a chain of hundreds, or more, amino acid units. There are 20 different amino acids found in food and body proteins. By being linked together in different combinations and proportions an almost endless variety of different proteins can be formed. Every species of plant or animal has its own characteristic proteins. Beef proteins are different to lamb proteins and both are different to pea proteins, etc. In humans, the protein in bone is different from the protein in skeletal tissue, or heart, blood or skin.


Proteins are needed in the body for:

1. Body growth and repair: building and maintenance muscles and other soft tissues

2. Regulation: proteins and amino acids are or are part of compounds that regulate or modulate the processes in the body, such as enzymes, hormones, antibodies and neurotransmitters.

3. Energy: to burn as fuel (i.e. to provide a source of energy).

Proteins are found in all active tissues of the body (e.g. muscle cells, the liver, glands, etc). Though one gram of protein can yield 4 calories, the most important functions of the protein are tissue building, and repair and provision of the ingredients for the formation of enzymes, hormones and antibodies.

Protein use depends on the following:

The all or none rule

An appropriate amount of all necessary amino acids must be present to make a particular protein, or the protein will not be made. Any essential amino acids not used to make proteins will soon be oxidised for energy, or converted to produce carbohydrates or fats.

Calorie intake adequacy

If a diet doesn't contain adequate carbohydrates or fats for calories in energy production as ATP, tissue proteins are then used for energy. (NB: ATP is a chemical involved in the process of storage and release of energy, allowing work and movement to occur in the body).

Body nitrogen balance

In healthy adults, the rate at which proteins are synthesised should be the same as the rate at which they are being broken down in the body. This balance is reflected by the nitrogen balance in the body based on the fact that all protein average approximately 16% nitrogen.

The body is considered in balance when the amount of nitrogen ingested in protein is equal to the amount excreted in urine. Under physical or emotional stress, the protein breakdown can be affected and exceed by the amount of protein being synthesised: this is called a "negative nitrogen balance".

Hormone activity

Anabolic hormones can cause acceleration of protein synthesis and growth. The effect of these hormones may continuously change (affected by things such as age, stress, growth rate etc), hence growth rates and protein synthesis rates can be continuously changing.

RECOMMENDED PROTEIN INTAKE

As a general guide: approximately 0.8-1g per kilogram of body weight per day. Typically a small serve of fish and an egg would be adequate for an average person, per day. Protein needs vary much among different people, depending on their metabolism, physical activity and health conditions. A sports person will need to rebuild muscles more often that a sedentary one. They will also have higher metabolic rates. So their protein consumption will need to adapt to higher requirements, and can be as high as 1.2-1.4g of protein per kg of body weight. People with kidney stones will have to be careful about their nitrogen intake, as in concentrated proteins sources, as a high intake will tend to stress the kidney in an attempt to increase urea elimination. According to the theories behind Metabolic Typing, some people may require more proteins in their diet, as much as 55%, and others may require less protein and more carbohydrates, as much as 70%. This is due to genetic differences in the way biochemistry cycles occur in our bodies, if people are fast or slow oxidisers.

Proteins sources are very varied, they can be supplied with plant or animal sources, and both of them lead to good health provided the essential amino acids are supplied and an adequate total quantity of protein is ingested. Too much protein is as bad too little. Moderation is the key. Too many proteins can lead to blood pH unbalances, which will put stress on other bodily systems in order to equilibrate the pH. Also, protein degradation will produce residues that will need to be eliminated from the body.

Animal sources of proteins are animal meats, poultry, fish, dairy and eggs. Plant sources of proteins include seeds, nuts and beans, grains, leafy greens, other vegetables and fruits.

GRAIN

Grains are a good source of protein, complex carbohydrates, fibre and many different minerals and vitamins. Different grains have different food values. Typically they consist of 65-75% carbohydrates (sugars and starches), 7 to 12 % proteins, 2 to 6% lipids and the rest is water. Whole grains are generally better nutritionally than processed grains, particularly with respect to dietary fibre, minerals and vitamins. Grains are a staple component of many diets in many cultures around the world, including Western countries. They are a basic component of daily protein intake in Western and Asian vegetarian and vegan diets, together with beans, nuts and seeds.