Nutrition Midterm 1

Front 1

Things your body renews itself in daily

Back 1

Cells
Tissue
Hair
Skin

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3 basic functions of nutrients

Back 2

Energy: Carbohydrate, fat and protein have potential energy that is released when chemical bonds are broken

Structure: e.g. Protein and calcium to form bone

Regulation: e.g. Proteins help regulate body fluid balance

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6 classes of nutrients (50 total) and % in body

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1. Proteins (18-20%)
2. Carbohydrates (<1%)
3. Fats (15-25%)
4. Minerals (4-5%)
5. Vitamins (<1%)
6. Water (55-60%)

Inverse Fat-Water % (Men lower Fat, higher Water)

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Essential Nutrients

Back 4

A nutrient the body cannot make at all or cannot make in sufficient amounts relative to its needs. It must be obtained from foods.

Examples: Calcium and Water

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Recommended Dietary Allowance (RDA)

Back 5

Daily amount of nutrients considered adequate to meet the needs of nearly all healthy people in the population. A generous value that is designed to be averaged over multiple days.

Established for several age groups, gender and physiological status (pregnancy, lactation).

Adjustments made for bioavailability, diet
quality, losses due to food preparation

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Homeostasis

Back 6

The maintenance of relatively constant internal conditions through the efforts and control of many systems of the body

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Fraction of body water located intracellular/extracellular

Back 7

Intracellular: 2/3
Extracellular: 1/3

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Digestion (Physical and Chemical)

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The process by which food is broken down into a form that can be absorbed by the intestine. Occurs primarily in stomach and small intestine.

Physical: The moving and grinding of food (mouth, esophagus, and stomach).

Chemical: The chemical breakdown of food through the use of digestive enzymes (made by the pancreas). Starts in stomach with majority occurring in the small intestines.

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Absorption

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The process of moving nutrients into the body or bloodstream. Occurs on the surface of the small intestine.

Front 10

Chemical Structure of Protein

Back 10

3D shape that is designed to suit the protein's function. Made of hundreds of subunits, called amino acids. Amino Acids are joined together by peptides.

There are 20 R groups (what distinguishes different AA) that either interact with enviorment or other R groups.

Front 11

4 elements that make up amino acids

Back 11

Nitrogen - unique to protein and losses reflect protein replacement needs
Carbon
Hydrogen
Oxygen

Front 12

Protein Sequence

Back 12

Each protein has a unique sequence that dictates the protein's structure. The structure dictates function.

No amino acid can replace another amino acid in the sequence.

All 20 AA are found in our food/body in different amounts.

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Essential Amino Acids

Back 13

Of the 20 amino acids, 9 are essential.

Are the R group for amino acids that cannot be made, or cannot be made in sufficient quantities by the body. They must be obtained from food.

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Nonessential Amino Acids

Back 14

Body has ability to makes the NEAA from other components of diet.

Nitrogen is needed in diet to build a NEAA.

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Two reasons protein IS needed in diet

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1) A source of EAA

2) A source of nitrogen (needed to make NEAA)

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Function of Protein

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Structure - Makes bone and connective tissue (due to protein called collagen)

Energy - 4 kcal/g but no storage

Regulation - Regulates hormones, enzymes, immune system and fluid balance.

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Protein Digestion

Back 17

At the beginning of chemical digestion, acid disrupts the R groups and causes the protein to unfold. In the small intestine, an enzyme called protease chemically breaks the peptide bonds releasing individual amino acids. The end product of protein digestion is individual amino acids (both EAA and NEAA) from food and from digested intestinal track cell protein.

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How the Body uses Protein

Back 18

Body cells pulls individual amino acids needed to build the proteins it is instructed to make out of the "bucket". Even if the bucked is overflowing, only the amount of protein needed will be made due to homeostasis.

If a NEAA is missing, it can be made given a source of nitrogen. If a EAA is missing, the protein will not be made.

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Protein Turnover (and rates)

Back 19

Proteins throughout the body are constantly being made and broken down. This is a good thing because it allows our body to make more of a protein that might need immediately.

Not all proteins turn over (hair, skin, nails, stool and urine) and therefore dietary protein must be consumed to replace these proteins.

Fast - Intestine and blood
Medium - Muscle and skin
Slow - Brain and central nervous system

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Excess Protein

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More protein is NOT made.

The nitrogen is stripped off the amino acid leaving a carbon skeleton.

The nitrogen can be used to make NEAA or more usually, is transformed into urea and excreted in the urine.

The carbon skeleton contains potential energy that can be utilized immediately. Protein can not be stored, but it can be converted to and stored as fat.

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Protein Deficiency (Development)

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Early Development - Growth due to increase in number of cells. Deficiency can cause permanent damage including stunted growth and mental retardation.

Later Development - Growth by increase in cell size. Deficiency not as devastating.

Front 22

Protein Deficiency (Results)

Back 22

Edema - fluid balance disrupted
Intestinal problems - causes diarrehea and poor absorption
Distended abdomen - fatty liver
Infections - poor immune responce

Conditions:
Kwashiorkor: young children that are weaned from breast milk
Protein-calorie malnutrition: inadequate energy intake

High turnover proteins affected the most dramatically

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RDA for Protein

Back 23

The RDA for protein for adult men and women is 0.8 grams protein/kg body weight per day

Example: 50kg man/woman

50kg x 0.8g/kg protein per day = 40 g protein/day

1. The minimum value is determined based on nitrogen losses
2. Adjusted for variations in the population
3. Protein Quality.

Children need a higher proportion of EAA than adults

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Factors that Change Protein RDA

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Growth - relative to body weight, infants need more protein

Pregnancy and lactation - need more protein that before

Injury and illness - depends on situation

Exercise - people who engage in regular, vigorous exercise increase RDA by 0.4g/kg body weight.

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Daily Value for Protein

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50g based on 2,000kg diet

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Protein Quality

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Is a measure (direct or indirect) of the food protein’s essential amino acid content.

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Complete Protein

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All of the 9 essential amino acids are present and in proportion to relative need and is digestible.

ex. Beef

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Perfect Protein

Back 28

The best complete proteins you can get.

ex. Breast Milk and Egg Protein

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Incomplete Protein

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Low in one or more essential amino acids relative to need.

ex. Beans

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Protein Efficiency Ratio

Back 30

Indirect measurement of EAA content by growing rats a diet containing the protein in question.

PER = Weight Gained/Protein Eaten

ex high PER: Fish
ex low PER: Corn

Front 31

Chemical Score

Back 31

Direct measure of EAA by comparison to perfect protein. The chemical score of a protein is the lowest percentage computed. Only EAA impact quality.

Front 32

Limiting Amino Acid

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The limiting amino acid in a food protein is the lowest amount relative to need. Found in incomplete proteins and dictate chemical score.

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Why can a infant not eat only incomplete proteins?

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1. They are growing and require a higher percentage of EAA

2. Incomplete proteins lack certain EAA relative to need

3. They do not eat the volume of food to eat enough incomplete proteins make up the difference

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Energy

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The ability to do work (either metabolic or physical)

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Body's Metabolism

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Food and oxygen is combined and the chemical bonds are oxidized (burned) releasing their potential energy as heat.

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Calorie

Back 36

The energy released as heat.

One calories is the heat needed to raise 1 liter of water 1 degree Celsius.

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Bomb Calorimeter

Back 37

Used to determine the potential energy or calories value of foods.

Front 38

Physiological Fuel Value

Back 38

The amount of energy that is physiologically available to us.

Carbohydrates: 4 kcal/g after 5% loss to stool
Fat: 9 kcal/g after 5% loss to stool
Protein: 4kcal/g after 10% loss to stool and energy loss in urine (transfer of nitrogen to urea)

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Calorie Value of Foods

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- Calories in meals are additive and based on physiological fuel values
- Water, cholesterol, vitamins and minerals have 0 calories
- Fiber, which is an indigestible carbohydrate, has no available energy to us

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Daily Energy Needs

Back 40

1) Basal Metabolic Rate (heat/energy/calories needed to keep basic body functions going. A function of body surface area)
2) Thermic Effect of Food (energy needed to digest and assimilate food)
3) Activity (any activity above BMR)
4) Growth (building new tissue)

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Factors altering BMR

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1) Age (BMR drops 2-3% every decade)
2) Fasting (BMR drops 10-20% within 24 hours)
3) Exercise (greater BMR)

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Activity as % of BMR

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Sedentary - 30%
Light - 50%
Moderate - 70%
Strenuous - 100%

Front 43

Total Energy Requirement

example:

70kg male, light activity, gaining 500kcal per day

Back 43

BMR - 1.0 kcal/kgxhour X 70kg X 24 hours/day = 1680 kcal/day

Activity - 1680 kcal/day X .5 = 840 kcal/day

Gain - 500 kcal/day

TEF - 0.05 (1680kcal/day + 840 kcal/day + 500kcal/day) = 151 kcal/day

Total = 1680kcal/day + 840kcal/day + 500kcal/day + 151kcal/day = 3170kcal/day

Front 44

Carbohydrates Function

Back 44

Major function: Energy Source (for brain and muscle) during exercise. About half of your calories come from carbohydrates.

The storage form of carbohydrates in the body is glycogen.

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Monosaccharides

Back 45

There are three monosaccharides, a six carbon ring with water attached to each carbon, is also refereed to as simple sugars or carbohydrates.

Glucose - Basic sugar unit: blood, starch, table sugar. Main function is to provide energy.

Fructose - Fruit sugar

Galactose - Milk sugar

Front 46

Disaccharides

Back 46

There are three disaccharides, two six carbon rings joined together, is also refereed to as simple sugars or carbohydrates.

Sucrose - One glucose and one fructose molecule joined together. Food sources include cookies, candy, soda or anything made with table sugar or brown sugar.

Maltose - Two glucose molecules linked together. Breakdown unit from starch (found in malt, seed/bean sprouts).

Lactose - One glucose and one galactose molecule linked together. Milk sugar is found in dairy products.

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Polysaccharides

Back 47

Many six-carbon rings linked together. There are three polysaccharides (complex carbohydrates).

Starch (plant) - Made up for hundreds of glucose units linked together in straight chain. Food sources include grains, pasta, bread, vegetables and unripe fruits.

Fiber (plant) - Made of hundreds of glucose units. However linkage is different angle from starch and makes it indigestible for humans. Source of fiber include whole grains, vegetables, and seeds.

Glycogen (animal) - Made from hundreds of glucose in a long chain with many branches. Glycogen is stored in the muscle and liver of humans and other animals. There are NO food sources.

Front 48

Carbohydrate Digestion

Back 48

In the mouth: Chemical digestion begins by enzymes present in saliva

Stomach: No chemical digestion. Physical digestion makes a "smoothie"

Small Intestine: Chemical digestion restarts where pancreas squirts an enzyme and meal is processed into three disaccharides. They are still too big so maltase, sucrase, and lactase split the disaccharides and make monosaccharides.

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Lactose Intolerance

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The inability to digest the milk sugar lactose (common). Lactose is too big for absorption which causes intestinal problems. Lactose intolerance is not an allegy to milk.

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Fiber (and benefits)

Back 50

This is the indigestible carbohydrate structural material from plants. It contains potential energy but this energy is not available to us.

High fiber diet makes the mass of waste material larger and softer and reduces chance of constipation. This means a lower chance of developing hemorrhoids (swollen vessels) and diverticulitis (when lining of the intestinal wall becomes inflamed and forms small pouches). It results in a lower risk of cancer and heart diesease.

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Water-Insoluble Fiber

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Food sources include wheat grains and vegetables. When water-insoluble comes in contact with water, it swells up. It pushes against the intestinal wall and workouts the intestinal tract. This process avoids constipation. Decreases cancer risk (colon) and the incidence of intestinal disease.

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Water-Soluble Fiber

Back 52

Food sources of water soluble fiber includes fruits, beans and oats. When water-soluble comes in contact with water it forms a gel. It helps slow the stomach content into small intestines which makes you feel full longer. It decreases cardiovascular disease risk by lowering blood cholesterol level.

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Daily Value for Fiber

Back 53

25 g/day for 2,000 kcal diet

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Potential Energy

Back 54

This energy can be released or converted into other forms of energy.

Nutrients:
Protein (can not be stored)
Carbohydrates
Fat
Fiber (not available to us)