Biochemistry Exam Iii - Nutrition And Vitamins

Front 1

Eastern diet is rich in phyto-estrogens and is low fat*

Phyto-estrogens are:

- naturally occurring hormone-like compounds found in plant foods

- structural similarity to the human female hormone 17-β estradiol

- can bind to estrogen receptors and act as estrogen agonists and antagonists

The hypothesis is that phyto-estrogens have a protective effect against cancer due to their similarity in structure to estrogens (first postulated in the 1980s)

Back 1

The current hypothesis which explains the association between breast cancer and fat intake, is that the latter influences the secretion and metabolism of various hormones that promote or inhibit the growth of tumors, most notably the estrogens and prostaglandins.

Estrogens at high levels are known to initiate/promote carcinogenesis

Front 2

The fortification of grain products with folic acid to decrease the incidence of common birth defects (______ _____)

Back 2

spina bifida

Front 3

The iodinization of table salt to prevent _________, a developmental disorder associated with severe neurological and cognitive deficits in children,

Back 3

cretinism

Front 4

The promotion of diets low in cholesterol to prevent and to manage ___________ disease

Back 4

cardiovascular disease.

Front 5

Estimates of the amounts of nutrients required to prevent deficiencies and
maintain optimal health and growth

It consists of four reference standards for the intake of nutrients designated for
specific age group, physiologic state and gender:

1. Tolerable upper limit( UL):
2. Estimated average requirement (EAR):
3. Recommended dietary allowance (RDA):
4. Adequate intake (AI):

Back 5

The Dietary Reference Index ( DRI)

Front 6

Highest level of daily nutrient intake that is likely to
pose no risk of adverse health effects to almost all individuals in the general population

Back 6

Tolerable upper limit( UL):

Front 7

Used if a nutrient is essential but the experimental data
are inadequate to calculate an EAR or RDA.

The AI is believed to cover the needs of all individuals in a group but uncertainty of the data prevent being able to specify the percentage of individuals cover by this intake

Back 7

Adequate intake (AI):

Front 8

Average daily intake that is sufficient to meet the nutrient requirements of nearly all (97-98%) the individuals in an age and gender group.

It is normally set at two standard deviations above the EAR.

RDA= EAR + 2 standard deviations

Back 8

Recommended dietary allowance (RDA)

It is not the minimal requirement; rather is set to provide a margin of safety.

Front 9

Amount of nutrient estimated to meet the nutrient requirement of half of the healthy individuals in an age and gender group.

Back 9

Estimated average requirement (EAR)

Useful in estimating actual requirements in groups and individuals

Front 10

nutrient requirements of half of the healthy individuals

Back 10

Estimated average requirement (EAR)

Front 11

nutrient requirements of nearly all (97-98%) the individuals –

Back 11

Recommended dietary allowance (RDA)

Front 12

highest level of daily nutrient intake likely to pose no risk of adverse health effects – UL

Back 12

Tolerable Upper Limit (UL)

Front 13

nutrient is essential but the experimental data are inadequate to calculate an EAR or RDA -

Back 13

Adequate Intake (AI)

Front 14

All of the following are measures of what?

Body mass index
Biochemical markers
Other laboratory tests
Clinical symptoms.

Back 14

Measuring the state of nutrition

Front 15

body weight in relation to height

BMI= weight (Kg)/height (m2)

Back 15

Body mass index

Measures the state of nutrition

Front 16

Nitrogen excretion: reliable way of assessing daily protein requirements. The amount of protein oxidized by the body is estimated by measuring nitrogen in urine (80% is urea, the rest in hair, stool, sweat)

Plasma proteins: albumin, transthyretin (prealbumin) and transferrin

Vitamins and trace metals

Back 16

Biochemical markers:

Measures the state of nutrition

Front 17

Hemoglobin
Electrolytes
Iron metabolism
Daily fluid intake

Back 17

Other laboratory tests:

Measures the state of nutrition

Front 18

__________ is the study of how foods affect the expression of our genes and how individual genetic differences can affect the way we respond to nutrients (and other naturally occurring compounds) in the foods we eat.

The goal is to develop personalized nutrition profiles

Back 18

Nutritional Genomics or nutrigenomics,

Factors:
- Biological factors
- Physiological factors
- Disease & drug interactions
- Social factors
- Energy expenditure

Front 19

All of the following describe this factor:

- Genotype (sex)
- Digestion
- Absorption
- Metabolism
- Excretion of nutrients
- Age and phase of the life cycle

Back 19

Biological factors of nutritional state.

Front 20

1. Water

2. Calories (energy) from carbohydrate

3. Calories (energy) from protein

4. Calories (energy) from fat

5. 13 vitamins.
a. These typically function as enzyme cofactors, e.g., niacin (precursor of NAD and NADP), riboflavin (precursor of FAD, FMN)….

6. 16-21 minerals

Back 20

Six general classes of nutrients:

Front 21

Nutrient needed in large amounts (grams daily).

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Macronutrient

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Nutrient needed in small amounts (mgrams daily).

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Micronutrient

Front 23

How many calories are in one gram of:

Carbohydrates

(Complex, Simple (starches, fiber, sugars)

Back 23

4 kcalories per gram

Front 24

How many calories are in one gram of:

Lipids (Saturated, Unsaturated (mono-, poly-)

Back 24

9 kcalories per gram

Front 25

How many calories are in one gram of:

Proteins

Back 25

4 kcalories per gram

Front 26

How many calories are in one gram of:

Alcohol

Back 26

7 kcalories per gram

Front 27

______ __________ _____(BMR) is the energy expenditure required to maintain body function at a complete rest: 50-70%

30% for membrane transport
30% for metabolism

40% temperature, physical activity (and growth )

Back 27

Basal metabolic rate

Front 28

______ __________ _________ is the sum of basal metabolic rate, the thermal effect of food and the energy used up in physical activity

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Total energy expenditure

Front 29

1. Surface area (affects the heat loss)

2. Age (growth and lean muscle mass)

3. Sex (female/male)

4. Activity level

Back 29

Energy expenditure is affected
by four factors

Front 30

Structural components

Speed up chemical reactions

Serve as chemical messengers

Plasma proteins: osmotic balance, transport of substances in blood, fight infection…

Back 30

Protein

Role: Provide 4 kcalories of energy per gram, but the body uses protein for energy only if carbohydrate and fat intake is insufficient.

Animal protein: eggs, milk, meat, fish and poultry. Contain all of the essential aa

Plant protein: vegetable grains and beans. Lack one or more essential aa

Front 31

________ _______ refers to the relationship between the intake of nitrogen (protein) and its excretion (urea and ammonia)

Equilibrium: losses <-> intake

Back 31

Nitrogen balance

Front 32

Net increase in body protein

- Growing children
- Pregnant women
- Convalescing adults

Back 32

Positive nitrogen balance

Front 33

Net loss in body protein

inadequate protein intake (amount or lack of essential aa)

Injury (destruction of tissue)

- Trauma, illness, surgery or stress (protein catabolism)

Back 33

Negative nitrogen balance

Front 34

Recommended protein intake: ____ g/Kg body weight/day

Back 34

0.8 g/Kg body weight/day

Front 35

The RDA for carbohydrates is set at 130 g/day

Back 35

3 classes of carbohydrates

1. Starches
whole-grain bread, cereal, pasta, corn

2. Sugars
fruits, vegetables, milk, honey, sugar cane

(complex carbohydrates) and refined sugars (simple carbohydrates)

3. Fibers: plants

Front 36

Glycemic index times the amount of carbohydrate in a standard serving size of that food

Back 36

Glycemic load

Front 37

Measures the effects of carbohydrates on blood glucose.

Effect of 50 g of CH in a particular food on blood glucose levels compared to the effect of 50 g of glucose.

Back 37

Glycemic index

Front 38

Some fibers absorb bile acids (associated with high risk colon cancer at high levels)

Fibers that increase fecal bulk decrease the intraluminal concentrations of carcinogens

A shortened fecal transit time decreases the time during which toxins can be synthesized and in which they are in contact with the colon.

Fiber fermentation to short-chain fatty acids decreases the interluminal pH, thereby decreasing synthesis of secondary bile acids (which promote the generation of tumors)

Back 38

Reasons why fiber prevents colon cancer.

Degradation of fiber by fermentation may release fiber-bound calcium. The increased calcium in the colon may help eliminate the mitogenic advantage that cancer cells have over normal cells in a low-calcium environment.

Butyric acid appears to slow the proliferation and differentiation of colon cancer cells.

Insoluble fibers such as lignin that resist degradation bind carcinogens, thereby minimizing the chances of interactions with colonic mucosal cells.

Front 39

Energy storage

Thermal insulation

Components of biological membranes

Signaling molecules

Synthesis of prostaglandins, leukotrienes and related compounds

Back 39

Role of fats

Front 40

Palmitic (C16)
Stearic (C18)
Myristic (C14)
Lauric (C12)

In all animal fats, palm oil, cocoa butter and coconut oil

Back 40

Saturated fats

Front 41

Monounsaturated: Oleic acid (w-9). In olive oil.
Polyunsaturated:

arachidonic and linoleic acid (w-6; in nuts, olives, soybeans);

a-linolenic (in plants),

eicosaspentaenoic and

docosahexaenoic (w-3; in fish)

Back 41

Unsaturated fatty acids

Essential fatty acids: linoleic and a-linolenic

Front 42

More than 30% fat is considered unsafe:

- Increase risk heart disease
- Obesity
- High blood pressure
- Diabetes
- Cancer: colon, prostate, breast…
- Can promote high cholesterol

Back 42

The importance of a low-fat diet.

Front 43

Cholesterol

Mostly endogenously synthesized; only 10-20% comes from the diet

Synthesis is highly regulated (changes in dietary cholesterol have little impact)

Back 43

Levels are influenced by:

1. Genetics (ApoE..)
2. Dietary fiber (absorption)
3. Type and amount of dietary fat

Front 44

High omega-3’s result in:
1. Reduced synthesis of VLDL and fatty acids
2. decrease in cholesterol synthesis
3. enhanced activity of LDL receptors
4. increased b-oxidation of fatty acids
5. inhibit formation of arachidonic acid
6. reduce platelet activity (prolong blood clotting)

Back 44

The relative amount of w-3 fatty acids with respect to arachidonic acid determines the type of prostaglandines and leukotrienes prevalent in the individual

Negative effects: reduce immunity (IL1-a and b and TNFa)

Front 45

What is undernutrition?

Back 45

Below RDA or AI

Front 46

What is overnutrition?

Back 46

Above UL

Front 47

The large intestine absorbs _____-______ fatty acids.

Back 47

short-chain fatty acids

Front 48

The ______ absorbs:

1. Lipids
2. Monosaccharides
3. Amino acids
4. Small peptides

Back 48

The jejunum

Front 49

What is basal metabolic rate?

1. Biosynthesis anabolism
Chemical work
2. Active transport
Osmotic work
3. Muscular contraction
Mechanical work

Back 49

50-70% of total energy expenditure

Front 50

Essential amino acids for children?

Back 50

Cysteine
Tyrosine
Arginine

Front 51

What is the macromolecule?

130 g/day
Set for adults and children alike

Minimal amount the brain needs for energy

RDA is not normally set this way

Back 51

Total amount of carbohydrates needed per day.

Front 52

Which is more accurate, glycemic load or glycemic index?

Back 52

Glycemic load is more accurate than index.

Takes into account the serving size of food.

Front 53

Can absorb up to 24x their weight in water.

Decrease intracolonic pressure and transit times

Decrease sugar uptake - controls sugars

Decrease pH

Decreases the formation of short-chain fatty acids

Back 53

Benefits of cellulose (amongst many)

Hemicellulose:
Produces butryic acid

Slows the proliferation and differentiation of colon cancer cells

Front 54

Most common form of Protein Energy Malnutrition in the US

Back 54

hospitals

Front 55

Excess protein intake causes:

Back 55

Increased loss of calcium

Obesity

Front 56

Dry, brittle hair
Dermatitis
Diarrhea
Retarded growth.

Problems fighting infection (reduced T-lymphocytes, defects in generation of phagocytic cells and production of immunoglobulins)

Back 56

Kwashiorkor

Hint 56

Inadequate intake of protein with adequate intake of energy.

Front 57

Thin, wasted appearance

Individuals are small for their age.

Permanent stunt in mental and physical conditions if diet does not change.

Problems fighting infection (reduced T-lymphocytes, defects in generation of phagocytic cells and production of immunoglobulins)

Back 57

Marasmus

Hint 57

Inadequate intake of protein and energy.

Front 58

Decreased serum proteins and cellular immunity

Delayed wound healing

Decreased resistance to infection

Increased mortality.

Back 58

Protein Energy Malnutrition

Hint 58

Most common form of Protein Energy Malnutrition in the US = hospitals

Front 59

Symptoms
Pellegra like skin eruptions
Cerebellar ataxia
Gross aminoaciduria

Back 59

Hartsnup disease

Mutations in SLC6A19: encodes the B0 AT1 neutral amino acid transporter)

Partly responsible for absorption of tryptophan

Hint 59

Impaired neutral amino acid transport in the:
1. Apical brush border of the small intestine
2. Proximal tubule of the kidney

Front 60

Amino acids are retained within the intestinal lumen, where some are converted by bacteria to indolic compounds that can be toxic to the CNS.

Tubular renal transport is also defective, contributing to gross aminoaciduria.

Neutral amino acids are also found in the feces

Decrease tryptophan absorption => decrease niacin (NAD, NADP).

Some symptoms are similar to niacin deficiency (pellagra-like)

Back 60

Hartsnup disease


Treatment:
1. Diet
Symptoms in persons with Hartnup disorder quickly respond to nicotinic acid supplementation and they require also other vitamins (B) and tryptophan

Hint 60

Tryptophan is converted to indole in the intestine that is absorbed converted to 3-hydroxyindole (ie. indican) in the liver and subsequently transported to the kidneys for excretion (ie, indicanuria).

Mental retardation and short stature have been described in a few patients.

Malnutrition and a low-protein diet are the primary factors that contribute to morbidity

Most patients remain asymptomatic

A minority of patients have skin photosensitivity, neurologic and psychiatric symptoms

Front 61

1. Weight loss, anemia, chronic diarrhea, malnutrition.

2. Symptoms associated with multiple fat-soluble vitamin deficiencies:
- night blindness (Vit. A)
- rickets (vit. D)
- gastrointestinal bleeding (vit. K).

Back 61

Pancreatic insufficiency

Increased fecal excretion of fat (steatorrhea) with concurrent deficiencies of vitamins (specially fat soluble), minerals, CH and proteins

Hint 61

Diminished lipase activity

(i.e. chronic pancreatitis due to alcoholism or cystic fibrosis).

Front 62

1. Weight loss, anemia, chronic diarrhea, malnutrition.

2. Symptoms associated with multiple fat-soluble vitamin deficiencies:
- night blindness (Vit. A)
- rickets (vit. D)
- gastrointestinal bleeding (vit. K).

Back 62

Bile salt deficiency

Increased fecal excretion of fat (steatorrhea) with concurrent deficiencies of vitamins (specially fat soluble), minerals, CH and proteins

Hint 62

defective micellarization of fats which is necessary for absorption by small intestinal villi

(i.e. cirrhosis, bacterial overgrowth in the small bowel with destruction of bile salts)

Front 63

1. Weight loss, anemia, chronic diarrhea, malnutrition.

2. Symptoms associated with multiple fat-soluble vitamin deficiencies:
- night blindness (Vit. A)
- rickets (vit. D)
- gastrointestinal bleeding (vit. K).

Back 63

Small bowel disease

Increased fecal excretion of fat (steatorrhea) with concurrent deficiencies of vitamins (specially fat soluble), minerals, CH and proteins

Hint 63

associated with a loss of the villous surface.

Leads to malassimilation of fats, proteins and carbohydrates.