2 the only diet you will ever need tp_2013

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Asst. Prof. Theeraporn PuntheeranurakDepartment of Biology, Faculty of Science

Mahidol UniversityEmail: [email protected]

SCBI 109 Integrated Biology

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The Only Diet You Will Ever Need 2.1 Nutrients

- Macronutrients- Micronutrients

2.2 Enzymes and Metabolism- Enzymes- Calories and Metabolic Rate

2.3 Body Fat and Health- Evaluating How Much Body Fat is Healthful- Obesity- Anorexia and Bulimia

SCBI 109 Integrated Biology

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• Organisms are composed of matter.• Matter is anything that takes up space and has mass.• Matter consists of chemical elements in pure formand in combinations called compounds.

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Essential elements

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What are nutrients?• Essential substances that your body

needs in order to grow and stay healthy

• Some provide energy. • All help build cells and tissues,

regulate bodily processes such as breathing.

• No single food supplies all the nutrients the body needs to function.

Body needs certain essential ‘nutrients’for its well-being.

FUNCTIONS OF FOOD1. Energy-yielding,2. Body-building, and3. Protective foodstuffsaccording to predominant role they play in sustaining life.

Nutrients in the Human Diet

• Macronutrients– Water– Amino Acids and

Proteins– Lipids– Carbohydrates

• Micronutrients– Vitamins– Minerals

Six categories of nutrients:

MacronutrientsFunction and sources of carbohydrate

Carbohydrate provides the main source of energy for the body.

Some forms of complex carbohydrates may reduce cholesterol which is beneficial for health.

Further classification of carbohydrate

There are different ways to classify carbohydrate.

One method is into:

1) sugar;

2) starch.

Classification of carbohydrateSugarMonosaccharides are the simplest form of carbohydrate molecules, e.g. glucose, fructose and galactose.

Disaccharides are formed when two sugar molecules join together, e.g. sucrose (glucose and fructose), lactose (glucose and galactose) and maltose (2 molecules of glucose).

StarchPolysaccharides are made up of many monosaccharide's molecules joined together, e.g. starch, glycogen, cellulose and pectin.

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- Monosaccharide (CH2O)n, n > 3 : simple sugars

Glucose, Fructose, Galactose, Ribose

Classification of carbohydrate

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- Oligosaccharide (with glycosidic linkage)Maltose, Lactose, Sucrose


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- Polysaccharide : starch, glycogen, cellulose, chitin

Storage polysaccharides

Structural polysaccharides

- Polysaccharide :

• complex carbohydrate

• compose of hundreds or thousands of monomer

• link by glycosidic linkage

• same monomer or different

• form of linkage can lead to different properties even made from the same monomer


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Another classification systems for sugars

Intrinsic can be described as sugars incorporated into the cellular structure of food,e.g. sugars in whole fruits and vegetables.

Extrinsic sugars can be described as not bound into cellular structure, e.g. lactose in dairy products.

Non-milk extrinsic sugars (NMES) are sugars not bound into cellular structure and also not found in milk,e.g. honey, fruit juices, table sugar and confectioneryare all examples of foods containing NMES.

Excessive consumption of carbohydrate

Increased body weight When too much carbohydrate is consumed and not used for energy over an extended period of time, it is stored as fat. Building up too much fat will increase body weight.

Increase dental cariesIt is important that teeth are brushed twice a day and foods high in sugar should be eaten with main meals, rather than in between snacks to prevent dental caries.

Lack of carbohydrate

The short term effects of a lack of carbohydrates are weight loss and lethargy (drowsiness).

Kwashiorkor (lack of protein) and Marasmus (total lack of nutrient) are two forms of deficiency disease which can develop in extreme conditions. These occur where energy and protein are lacking in the diet over an extended period of time.

Protein

Protein is needed for growth, development and repair of the body.

Excess protein can be broken down and used as a source of energy.

Protein is made up of different combinations of amino acids. These are the building blocks of protein. Amino acids are compounds containing carbon, hydrogen, oxygen, nitrogen

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20 amino acids of proteins (essential and non-essential)

The amino acids are grouped here according to the properties of their side chains (R groups).

ProteinIndispensable or dispensable?

The human body is able to make most amino acids itself and these are known as non-essential or dispensable amino acids. There are some amino acids that cannot be made by the body. They are called indispensable amino acids (IAA) or sometimes essential amino acids. (phenylalanine, valine, threonine, tryptophan, isoleucine, methionine, leucine, lysine, histidine* and arginine*, *essential for infant)

It is essential that these are provided in the diet as the body cannot make them.

Body needs

Adults only need 8 indispensable amino acids for growth and repair.

Children need to obtain 10 indispensable amino acids.

(phenylalanine, valine, threonine, tryptophan, isoleucine, methionine, leucine, lysine, histidine* and arginine*, *essential for infant)

Biological value and complementation

It is not just the amount of protein, but the quality or biological value of the protein that needs to be considered.

If a protein contains all the indispensable amino acids it is said to have a high biological value.

If a protein does not contain all the indispensable amino acids it is said to have a low biological value.

High and low biological value

High biological value (HBV) proteins include:meat, fish, eggs, cheese, and milk.

Low biological value (LBV) proteins include:cereals, pulses, some nuts and vegetables.

In general, animal protein sources have a higher biological value, than vegetable sources.

Vegetarians and vegans need to eat wisely to ensurethey are getting all the indispensable amino acids.

The body’s needs for protein

Babies and children have a high need for proteinbecause they are growing.

Adolescents need protein for their rapid growth spurt.

Pregnant women need more protein than other adults because of the growing baby.

Nursing mothers also need more protein for lactation.

Protein deficiency

Protein deficiency is rare, but there is a condition called PEM – protein energy malnutrition. This can be seen in infants with stunted growth or thin arms and legs, and large distended abdomens.

Marasmus (total lack of nutrient) - this condition mainly affects infants causing them to become thin and weak. The body adapts to the shortage of energy and nutrients. All energy stores are depleted as it is used to supply vital organs.

Kwashiorkor (lack of protein) - this condition is known to be the body’s adaption to shortage of energy and nutrients.

Fat

Fat performs many functions in the body including:

• providing essential fatty acids;• providing a concentrated source of energy;• carrying fat soluble vitamins and is important for their

absorption;• surrounding and protecting body organs;• forming an insulating layer keeping the body warm.

Fat is made up of fatty acids and glycerol.

Glycerol

Fatty Acid 1

Fatty Acid 2

Fatty Acid 3

Essential fatty acids

The body can make most fatty acids.

Essential fatty acids (EFA) are required for important functions in the body. These must be provided by the diet because our bodies cannot make them.

Two EFAs are known for humans: alpha-linolenic acid (an omega-3 fatty acid) and linoleic acid (an omega-6 fatty acid).

Sources of saturated and unsaturated fats

• Saturated fatMeat, coconut oil, palm oil, cakes and biscuits, lard.

• Unsaturated fat* Mono unsaturated fatRapeseed oil, avocado and olive oil.

* Polyunsaturated fatOily fish, sunflower oil and pine nuts.

Over consumption of fat

Eating too much saturated fat has become a problem in our society.

There are many health problems linked with too much saturated fat in the diet, e.g. coronary heart disease, and strokes.

Micronutrients

Micronutrients

Micronutrients are needed in much smaller amounts than the macronutrients.

In general vitamins are needed to regulate the maintenance and growth of the body, and to control metabolic reactions in cells.

Most vitamins are provided to the body through the diet, however, the body can make vitamin D, vitamin K and niacin.

Vitamin A (retinol, carotene)

Vitamin A is fat-soluble vitamin needed for the normal structure and functioning of the cells in the skin and body linings, e.g. in the lungs.This vitamin also helps with vision in dim light, as well a keeping the immune system healthy.

It is found in two forms; retinol in foods from animal sources and carotenoids (the most abundant of which is the beta-carotene) from plant sources.

Vitamin A – retinol is found in liver and whole milk, Vitamin A – carotenoids are found in dark green leafy vegetables, carrots and orange coloured fruits.

Too much or too little?

Deficiency leads to poor vision in dim light or night blindness. Severe deficiency can lead to total blindness.

Vitamin A is stored in the liver and too much vitamin A can be toxic.

Consuming too much vitamin A whilst being pregnant has been linked to birth defects.

Vitamin D (Cholecalciferol)Vitamin D is needed for the absorption of calcium and phosphorous from foods, to keep bones healthy.

Recent research also suggests that vitamin D enhances immune function and improves muscle strength.

Vitamin D is found in the diet, but most of our vitamin D is made in the body the action of ultra violet rays on the skin.

Vitamin D occurs naturally in some animal products, including fish liver oils, oily fish, egg yolk, and butter.Cereals, margarine and low fat spreads are also fortified with vitamin D.


Deficiency of vitamin D leads to rickets (โรคกระดกูออ่น) and the formation of soft bones. This causes the bones in the legs to bend. Deficiency in adults causes Osteomalacia resulting in pain and muscular weakness.

Vitamin D can be stored by the body. Too much vitamin D can lead to excess levels of calcium in the blood.

Young children, housebound older adults, and people who practice religions where their skin must be covered, may be at risk of deficiency through lack of exposure of their skin to sunlight.

Vitamin E (Tocopherol)

Vitamin E is a group of similar molecules with common properties and functions.

Vitamin E acts as an antioxidant and protects cells in the body against damage.

Vitamin E is mainly found in vegetable oils, nuts, seeds and wheat germ.

Deficiency and excess of vitamin E

A deficiency in this vitamin is rare because it is so widely available in the diet.

In very rare cases neurological disabilities such as lost reflexes have developed.

Vitamin E has a low toxicity, but in very large doses may interfere with absorption of vitamin A.

Vitamin K

Vitamin K is needed for normal clotting of blood and is also required for normal bone structure.

Infants are given vitamin K at birth.

Vitamin K is also produced by the bacteria in the gut.

Vitamin K is found in green leafy vegetables e.g. broccoli, lettuce, cabbage, spinach and meat and dairy products.


Deficiency of vitamin K is rare in adults, but is sometimes seen in new born babies.

Thiamin (B1)

Thiamin is needed for the release of energy from carbohydrate. It is also involved in the normal functioning of the nervous system and the heart.

Thiamin is mainly found in whole grains, nuts, meat (especially pork), fruit and vegetables and fortified cereals.


Thiamin deficiency can lead to the development of the disease beri-beri. Symptoms include fatigue, weakness of the legs (ชาปลายเท้า) and anorexia (ไมอ่ยากอาหาร).

As the body excretes any excess thiamin, there is no evidence of any toxic effects of high doses.

Riboflavin (B2)

Riboflavin is needed for the release of energy from carbohydrate, protein and fat.

It is also involved in the transport and metabolism of iron in the body and is needed for the normal structure and function of skin and body linings.

Riboflavin is found in milk, eggs, rice, fortified breakfast cereals, liver, legumes, mushrooms and green vegetables.


There is no deficiency related disease, however, the tongue, lips and skin become affected when the body is low in riboflavin (ปากนกกระจอก).

As the body excretes any excess riboflavin, there is no evidence of any toxic effects of high doses.

Niacin (B3)

Niacin is important for releasing energy from food, and is important for the normal structure of the skin and body linings.

Niacin is also needed for the normal functioning of the nervous system.

Niacin can be found in meat, wheat and maize flour, eggs, dairy products and yeast.


Deficiency of niacin can result in the disease pellagra. Symptoms can include:• dermatitis (คนัตามผิวหนงั, ภมูิแพ้);• dementia (โรคสมองเสื่อม);• diarrhoea.

Problems associated with excessive intakes are rare.

Vitamin B12

Vitamin B12 is needed for the formation of red blood cells and the normal functioning of the nervous system.

Vitamin B12 also helps to release energy from food.

Vitamin B12 is found exclusively in animal products, plant products do not provide any vitamin B12.It is found in meat, fish, cheese, eggs, yeasts extract and fortified breakfast cereals.

Deficiency of vitamin B12

Deficiency of vitamin B12 can lead to pernicious anaemia (โลหิตจาง).

It can also lead to some neurological problems.

Deficiency is rare, but may be a problem for people following strict vegan or vegetarian diets.

Folate (Folic acid)

Folate is important for the formation of healthy red blood cells.

It is also needed for the nervous system and specifically for the development of the nervous system in unborn babies.

It can reduce the risk of neural tube defects in a fetus, e.g. spina bifida.

Good sources of folate include green leafy vegetables brown rice, peas, oranges, bananas and fortified cereals.

Deficiency of folate

Deficiency of folate can lead to megaloblastic anaemia. Symptoms can include insomnia (โรคหลบัยาก), depression and forgetfulness.

It is recommended that all women who are planning a pregnancy take a daily supplement of folic acid. Once pregnant, supplementation should continue for the first 12 weeks to reduce the risk of neural tube defects.

Vitamin C (Ascorbic acid)

Ascorbic acid is needed to make collagen which is required for the normal structure and function of body tissues, such as skin, cartilage and bones.

It also acts as an antioxidant that protects the body from damage by free radicals.

Sources of ascorbic acid include fresh fruits, especially citrus fruits and berries, green vegetables, peppers and tomatoes. Ascorbic acid is also found in potatoes (especially in new potatoes).


Scurvy (ลกัปิดลกัเปิด) can result from lack of ascorbic acid. It tends to occur in infants and the older adults.

Scurvy leads to spots on the skin, bleeding gums and loose or loss of teeth.

Over nutrition of ascorbic acid is rare.

Minerals

Minerals are inorganic substances needed by the body for many different functions.

Some minerals are needed in very tiny amounts, these are known as trace elements, such as fluoride.

Calcium (Ca)

Calcium is important for the formation and maintenance of strong bones and teeth, as well as the normal functioning of nervous system and muscles.

It is also involved in blood clotting.

Milk and dairy products are the most important sources of calcium. Other sources include bread, calcium enriched soya products, green leafy vegetables and fish with soft edible bones.


Poor intakes of calcium can result in poor bone health which can increase the risk of diseases such as osteoporosis later in life.

Taking high doses of calcium supplements can cause stomach pains and diarrhoea.

Iron (Fe)

Iron is needed for needed for the formation of haemoglobin in red blood cells which transport oxygen around the body.

It is also required for energy metabolism and has an important role in the immune system.

Haem iron is present in animal sources in the form of haemoglobin. Non haem iron is present in plant sources such as beans, nuts, dried fruits, wholegrains, soya bean flour and dark green leafy vegetables.


A lack of iron will lead to anaemia. Symptoms include:

• feeling of tiredness; • lacking in energy; • general weakness; • poor concentration.

Too much iron in the diet can result in constipation, nausea and vomiting.

Phosphorus (P)

Phosphorus is essential for the structure bones and teeth, for the structure of cell membranes and for energy metabolism.

Phosphorus is found in red meat, dairy products, fish, poultry, bread, rice and oats.

Potassium (K)

Potassium is essential for water and electrolyte balance and normal functioning of cells, including nerves.

Potassium is present in all foods, but found richly in fruit (dried fruits, bananas, berry fruits), leafy green vegetables (e.g. broccoli and spinach) meat, nuts, seeds and pulses.

Sodium (Na)

Sodium is needed to regulate body water content and electrolyte balance.

Sodium is also needed for the absorption of some nutrients and water from the gut.

Sodium is present in very small amounts in raw foods. It is often added as salt during processing, preparation, preservation and serving.

High salt processed foods include bacon, cheese, yeast extract and smoked fish.


Consuming too much sodium increases the risk of high blood pressure. High blood pressure is linked with an increased risk of heart disease and stroke.

Sodium deficiency is unlikely, but can be caused by excessive sweating or vomiting and diarrhoea.

It is recommended that adults and children over the age of 11 years cut down on salt and consume no more than 6g per day.

Fluoride (F)

Fluoride is needed for the formation of strong teeth and protects against dental decay (caries).

Fluoride is a trace element, therefore only a small amount is required for good health.

Fluoride can be found in drinking water and in small amounts in tea and saltwater fish. Some areas add fluoride to the drinking water.Fluoride toothpastes are another important source.


An excessive intake of fluoride can lead to mottling or discolouration of teeth.

Nutrient interactions

Some nutrients work together in the body completing different functions.

For example:• the vitamins A,C and E;• calcium phosphorus and fluoride;• calcium and vitamin D;• iron and vitamin C;• carbohydrates and B vitamins.

Anti-oxidants

Vitamins A, C and E are anti-oxidants and work together in the body to protect cells against oxidative damage from free radicals.

This damage to cells can increase the risk of developing diseases such as heart disease and cancer.

Calcium, phosphorus and fluoride

These nutrients are involved in the mineralisation of teeth and bones which keep them hard and strong.

Vitamin D and calcium

Vitamin D controls the amount of calcium available. A lack of vitamin D in the body results in reduced absorption of calcium.

Iron and ascorbic acid

Ascorbic acid aids the absorption of non haem iron (non meat sources of iron) when eaten at the same time.

This is particularly important for people following strict vegan or vegetarian diets.

Carbohydrates and Vitamins B

Riboflavin and thiamin are involved in the release of energy from carbohydrate.

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• A fundamental task of proteins is to act as enzymes—catalysts

that increase the rate of all the chemical reactions within cells

(over a millionfold).

• Enzymes increase the rate of chemical reactions without

themselves being consumed or permanently altered by the

reaction.

– A substrate is a molecule that is acted upon by an enzyme.

– A product is a result of the reaction between the enzyme and the

substrate.

Energy diagrams for catalyzed and uncatalyzed reactions • An enzyme converts a substrate to a higher energy state, or

transition state.

• Activation energy is the energy required to reach the transition

state, which constitutes a barrier to the progress of the

reaction.

• The substrate binds to a specific region of the enzyme called the

active site.

• The binding of a substrate to the active site of an enzyme is a very

specific interaction.

• Most biochemical reactions involve interactions between two or

more different substrates.

• The simplest model of enzyme-substrate interaction is the lock-and-

key model in which the substrate fits precisely into the active site.

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• mostly adds –ase at the end of substrate name eg.

maltase, lipase, protease, sucrase, cellulase, amylase

• or at the end of reaction name eg. hydrolase, isomerase,

dehydrogenase, kinase, ligase

• effects of enzyme activity

• temperature

• pH (acid-base)

• inhibitor

• etc.

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• Coenzymes are low-molecular-weight organic molecules that participate

in specific types of enzymatic reactions by working together with

enzymes to enhance reaction rates.

• Nicotinamide adenine dinucleotide (NAD+) is a coenzyme that functions

as a carrier of electrons in oxidation-reduction reactions.

Role of NAD+ in oxidation–reduction reactions

• Several other coenzymes also act as electron carriers, and still

others are involved in the transfer of a variety of additional chemical

groups.

• Many tasks that a cell must perform, such as movement and the

synthesis of macromolecules, require energy.

• The totality of an organism’s chemical reactions is called

metabolism (from the Greek metabole, change).

• Energy is the capacity to cause change. In everyday life, energy is

important because some forms of energy can be used to do work-

that is, to move matter against opposing forces, such as gravity and

friction.

• Calorie: a unit of energy. The calorie approximates the energy needed to

increase the temperature of 1 gram of water by 1 °C.

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Metabolic Rates and Weight

• Basal Metabolic Rate (BMR) – the amount of energy your body uses at complete rest

• About 60–70% of calories consumed per day support BMR

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The nutrition facts label (also known as the nutrition information panel) is a label required on most packaged food in many countries.

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Nathan’s Famous Hot Dog Eating Contest Yields Frightening Nutrition Facts

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The glycemic load (GL) of food is a number that estimates how much the food will raise a person's blood glucose level after eating it.

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BMI• Body Mass Index

• The term BMI is often used when discussing the obesity epidemic

• BMI is a tool for indicating weight status.

• It is a number that shows body weight adjusted for height.

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• Body Mass Index (BMI) formula:

o Weight (kg) / height squared (m2) or

o Weight (lbs) x 704.5 / height (in.) / height (in.)

• 60 kg / (1.60 m x 1.60 m)

• 60 / 2.56 = 23.4 BMI

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Body Mass Index: Are You at a Healthy Weight?

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Above a Healthy Weight

• If your BMI lies above the normal area, then you may be at greater risk for health problems such as high blood pressure, heart disease, diabetes, and certain cancers.

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Below a Healthy Weight

• If your BMI lies below the normal area, then you may be at risk for health problems such as irregular heart rhythms, depression, anemia, and osteoporosis.

• Some people have a low BMI, but are eating well and have lots of energy. The best advice for people below a healthy weight is to be aware of their health risks and maintain a stable weight by eating well and keeping active.

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These men have the same height, weight, and BMI, but may have different percent

body fat.

6'3" Height 6'3" 220 lbs Weight 220 lbs 27.5 BMI 27.5

• BMI is only one of many factors used to predict risk for disease.

• It is important to remember that weight is only one factor related to disease.

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BMI is the not the only indicator for health risk

Other Factors That Are Important When Calculating Health Risk Include:

• Diet • Physical Activity • Waist Circumference • Blood Pressure • Blood Sugar Level • Cholesterol Level • Family History of disease

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ObesityOverweight and obesity are defined as abnormal or excessive fat accumulation that presents a risk to health. A person with a BMI of 30 or more is generally considered obese. A person with a BMI equal to or more than 25 is considered overweight.

• Waist circumference:– Men <40 inches (102 cm)– Women <35 inches (88 cm)

• Waist-to-hip ratio:– Men <1.0– Women <0.8

Obesity

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Selected Health Consequences of Overweight and Obesity

Portion Distortion:Do You Know How Food Portions Have

Changed in 20 Years?

French Fries20 Years Ago Today

210 Calories2.4 ounces

How many calories are in these fries?610 calories6.9 ounces

Calorie Difference: 400 calories

*Based on 160 pound person

How long will you have to walk to burn* 400 calories?How to burn* 400 calories:Walk leisurely for 1 hr 10 Minutes

Soda20 Years Ago Today

85 Calories6 ½ ounces


How many calories are in this soda?250 calories20 ounces


How long would you haveto garden to burn 165 calories?.

How to burn* 165 calories:

Garden for 35 Minutes

Turkey Sandwich20 Years Ago Today

320 calories


How many calories are in this turkey sandwich?820 calories


How long would you have to biketo burn up 500 calories?How to burn 500 calories:Bike for 1 hour and 25 minutes

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Anorexia and Bulimia

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Anorexia nervosa is a type of eating disorder. People who have anorexia have an intense fear of gaining weight. They severely limit the amount of food they eat and can become dangerously thin.

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Bulimia nervosa is an eating disorder characterized by binge eating and purging, or consuming a large amount of food in a short amount of time followed by an attempt to rid oneself of the food consumed (purging), typically by vomiting, taking a laxative or diuretic and/or excessive exercise. Bulimia nervosa is considered to be less life threatening than anorexia; however, the occurrence of bulimia nervosa is higher.

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2 the only diet you will ever need tp_2013