Human Nutrition Flashcards
1
Q
What is Total (daily) Energy Expenditure (TEE)
A
Sum of
1. Basal metabolic rate
2. Energy used during physical activity
3. Thermic effect of food
2
Q
Basal Metabolic Rate (BMR)
A
Resting metabolic rate; energy needed to maintain normal physiological functions when the body is at rest (60 to 70% of total energy expenditure)
3
Q
Factors affecting basal metabolic rate
A
- Gender (male > female)
- Age (children > adult)
- Health
- Hormones
4
Q
3 fat depots in the body
A
- Visceral fat
1. In abdominal cavity/belly
2. Produce molecule that promotes
atheroscelrosis, cardiovascular diseases, type
2 diabetes
3. This fat is loss first- Ectopic fat
- Obstructs heart/cardiac function
- Obstruct pharynx/respiratory function
- Ex. Cardiac and pharyngeal fat pads
- Subcutaneous fat
- Generally benign
- Source of energy
- Fat under skin
- Ectopic fat
5
Q
Carbohydrates
A
- Main energy source (along with fat)
- Some create sense of satiety overtime
- Some carbs are digested rapidly and stimulate craving -> promote fat deposition in tissues
- Fibre is indigestible -> for regulating gut motility and transit
- Energy content: 4.1 kcal/g
6
Q
Fats
A
- Main energy source (along with carbohydrates)
- Most important nutrient used for energy storage
- Linked to heart disease
- Energy content: 9.3 kcal/g
7
Q
Proteins
A
- Provide cell structure
- For cell functions, signalling, communications
- Last resort energy sources -> release amino acids from muscle
- Energy content: 4.1 kcal/g
8
Q
Essential Fatty Acids
A
- Linoleic acid/omega 6
- α-linoleic acid/omega 3
9
Q
Vitamins and Minerals
A
- Act as coenzymes, form functionally important prosthetic groups, for body functions and development, hormones, cell growth/proliferation/differentiation
Vitamins: non-caloric organic nutrient needed in small amounts
Minerals: non-caloric inorganic nutrient needed in very small amounts
10
Q
Main purpose of nutrients
A
- Supply energy
- Building blocks for synthesis of molecules
- Help metabolic pathways function
11
Q
4 Dietary Reference Intake (DRI) standards
A
- Estimated average requirement (EAR): level estimated to meet the requirement of 50% of the healthy individuals in a particular life stage and gender group
- Recommended dietary allowance (RDA): level sufficient to meet the nutrient requirements rof nearly all (97-98%) the individuals in a life stage and gender group
- Adequate inake (AI): estimates of nutrient intake by a group(s) of apparently healthy people that are assumed to be adequate
- Tolerable upper intake level (UL): highest level likely to pose no risk of adverse health effects to almost all individuals in a particular life stage and gender group
- Intakes between RDA and Ul have no risk of adverse effects
12
Q
What is the Malnutrition Universal Screening Tool
A
5 steps to identify adults who are undernutrition/obese
1. BMI score (kg/m^2)
2. Weight loss score
1. Unplanned weight loss in past 3-6 months
3. . Acute disease effect score
1. Whether patient is acutely ill and is there
no nutrition intake >5 days
4. Overall risk of malnutrition
1. Add scores from steps 1-3 together
5. Management guidelines
13
Q
3 forms of nutritional assessments
A
- Anthropometric measurements
- Pro: easy, portable, cheap, non invasive
- Con: more detailed analysis through other means
1. Body mass index (BMI)- kg/m^2
- Consider age and gender between ages of 2
to 20 - Limitations in subgroups such as athletes,
limb deformity, skeletal muscle mass loss- Waist to hip ratio
- Mid arm circumference
- Skinfold thickness
- Biochemical data
- Pro: Objective and qualitative
- Con: Not just nutrition involved, disease and
medication plays a part
1. Blood (plasma proteins, haemoglobin)
2. Urine (urinary nitrogen)
3. Feces
- Dietary data
- Not just dietary intake
- Meal patterns, amount and type of food
- Biological factors (affecting IAXM)
- Psychological factors (eating disorders)
- Sociological factors (availability of food, social
factors) - Cultural factors (eating patterns/food preferences)
1. Questionnaires, 24hr dietary recalls
2. Food records
3. Analysis of food
4. Metabolic balance studies
14
Q
Differences between fat soluble and water soluble vitamins
A
In:
1. Absorption
2. Transportation
3. Storage
4. Excretion
5. Deficiency
6. Excess
15
Q
What are the 4 A’s of vitamin A and what substance of the vitamin A pathway corresponds to each
A
- Antioxidant
- B carotene - Aura
- Retinal - Activation
- Retinoic acid - Abnormal pregnancy
- too much/too little vitamin A
16
Q
How does vitamin A relate to night blindness
A
- Retinal produces visual pigment rhodopsin
- Rhodopsin found in rod cells of retina and when exposed to light, changes conformation and elicit nerve signals to brain as light
- Rod cells responsible for vision in poor light -> without vitamin A/retinal night blindness occurs
17
Q
Besides night blindness, what does hypovitaminosis A cause
A
Keratomalacia, impaired wound healing, growth impediment
18
Q
What does hypervitaminosis A cause
A
- Birth defects like abnormal heart and cleft palates
- Liver toxicity
19
Q
Explain the vitamin D pathway
A
1a. 7-dehydrocholesterol on skin, using UV light, converted to
1b. Cholecalciferol and ergocalciferol from diet converted to
2. Cholecalciferol converted to
3. 25-hydroxyvitamin D (25-OH-D3) to be stored in liver, converted to
4. 1,25-dihydroxyvitamin D (1,25-(OH2)-D3) active form to be stored in kidney
- Function to maintain calcium levels in body
- When calcium level drop, active form mobilises calcium from bone, increase absorption from kidney and intestine to restore calcium level in blood
20
Q
What causes hypovitaminosis D and what happens
A
Caused by
- Inadequate diet
- Disruption of lipid absorption
- Poor functioning of liver and kidney
- Hypoparathyroidism
- Lack of exposure to sunlight
Manifest as brittle bones, bowing of knees
- Rickets (children) and osteomalacia (adults)
21
Q
What causes hypervitaminosis D
A
- Too much calcium in blood (hypercalcemia)
- Deposition of calcium in many organs (arteries and kidneys)
- Too much calcium in urine (hypercalciuria) formed kidney stones
22
Q
What does vitamin E do
A
An antioxidant that protect cells from reactive oxygen species (ROS) generated from free radicals reacting with oxygen. Free radicals damage molecules (nucleic acid, proteins, lipids)
23
Q
What happens in hypervitaminosis E
A
- Deficiency usually restricted to premature infants
- Defective lipid absorption/transport in adults (ex. cystic fibrosis, abetalipoproteinemia)
- Haemolytic anaemia: when red blood cells are destroyed faster than they can be made (erythrocytes susceptible to rupture -> haemolysis)
- Vitamin E prevents RBC oxidation
- Impaired vision
- Muscle weakness (myopathy)
- Peripheral neuropathy
- Ataxia (poor muscle coordination with tremors)
- Areflexia (loss of reflexes in limb)
- Poor proprioception (sensation of one’s position and movement)
- Decreased vibratory sensation
24
Q
What are the 4 K/C’s of vitamin K?
A
- Clotting factors
1. Vitamin K used to makes clotting factors, and warfarin inhibits this- Crushed by warfarin
- Co-factor of gamma-carboxylation
- This is how clotting factors are made
- Cannot be found in newborn infant
- Few days after birth would need food to obtain vitamin K
25
Describe the vitamin K pathway
- Phylloquinone from diet gets converted to the active form hydroquinone
- Basically, vitamin K/hydroquinone is needed as a cofactor to gamma carboxylase to activate the precursor clotting factor into the mature clotting factor to clot blood
- Once the clotting factor is activated and becomes the mature clotting factor, the vitamin K is in the form of epoxide
26
What is warfarin
Warfarin stops phylloquinone from turning into hydroquinone and epoxide from turning into phylloquinone
- Warfarin given to treat thrombosis and pulmonary thromboembolism and atrial fibrillation
- So blood would not clot so easily
27
When does hypovitaminosis K occur and what does that cause
Hypovitaminosis K
- Deficiency occur when
- Absorption of lipid disrupted
- Gut bacteria to synthesize vitamin K absent
- Wafarin (anticoagulation drugs)
- Susceptible to heavy bleeding and bruising
- Anaemic, weak, present with nose bleeds, bleeding gums, heavy menstrual bleeding, gastrointestinal bleeding
- Infant -> sterile gut, normalizes when fod absorption starts -> delayed in preterm infants
28
Hypervitaminosis K and what does it do
- No UL set
- Prolonged intake of synthetic vitamin K causes liver toxicity and haemolytic anaemia
29
Vitamin B1
- Thiamine
- Essential for carbohydrate metabolism
- Coenzyme of pyruvate dehydrogenase and alpha-ketoglutarate dehyrogenase
- Deficiency decreases these two dehydrogenase-catalysed reactions -> decreased ATP production -> impaired cellular function
- Thiamine deficiency = beriberi
- Where polished rice is major part of diet
- Associated with chronic alcoholism (Wernicke-Korsakoff syndrome)
30
Vitamin B2
- Riboflavin
- Forms part of FMN (flavinmononucleotide) and FAD (flavinadenin dinucleotide)
- FAD is coenzyme of succinate dehydrogenase/complex II, acetyle CoA dehydrogenase, retinal dehydrogenase, NADH dehydrogenase/complex I
- FMN and FAD coenzymes for vitamin activating enzymes
- Know that B2 is important in generation of ATP
31
Vitamin B3
- Niacin
- Forms part of NAD+ (nicotinamide adenine dinucleotide)
- NAD+ serves as an electron carrier -> NADH transfers electrons from the TCA cycle to complex of the electron transport chain
- Deficiency results in pellagra progressing through 3D's: dermatitis, diarrhea, dementia -> death
- Important for ATP generation
32
Vitamin B5
- Vitamin B5 (Pantothenic Acid)
- Component for coenzyme A
- Deficiency not well established
33
Vitamin B6
- Vitamin B6 (Pyridoxine)
- Coenzyme for many enzymes (amino acid metabolism)
- Deficiency causes neurological symptoms and anaemia
- High protein intake increases demand
34
Vitamin B7
- Vitamin B7 (Biotin)
- Coenzyme for synthesis of fat, glycogen, amino acid
- Deficiency can be caused by eating raw eggs
- Avidin in egg white combines with biotin and prevents absorption
35
Vitamin B9
- Folic acid
- One-carbon metabolism (series of pathways)-> essential for biosynthesis of several compounds
- Tetrahydrofolate (reduced folate) receives one-carbon fragments from donors (e.g. serine, glycine, histidine) and transfers them to intermediates in synthesis of amino acids, purines, and TMP (pyrimidine found in DNA)
- Deficiency results in megabloblastic anaemia caused by diminished synthesis of purines and TMP
- Cells in bone marrow so enlarged with fragile membranes with tendency to lyse
- Low blood cell count and anaemia
- Cells unable to make DNA
- Cells cannot divide
- Deficiency results in neural tube deficiency during this time in early pregnancy
- Folic acid drives nucleic acid synthesis and rapid cell growth during neural tube developmet
36
Vitamin B12
- Cobalamin
- Rapidly dividing cells (erythropoietic tissues) need to use a certain form of tetrahydrofolate and cobalamin helps with utilizing it -> helps in nucleic acid synthesis and production of erythrocytes
- When this form is utilized, this folic acid is recycled
- Deficiency results in symptoms of megloblastic anaemia
37
Vitamin C
- Ascorbic acid
- Preserved food at sea does not have vitamin C -> scurvy was common
- Functions
- Antioxidants: (like Vitamin E) protect from harmful effects of ROS generated from free radicals reacting with oxygen
- Reducing agent: Keeps iron in its reduced state (Fe3+ to Fe2+) to help with collagen folding and stability (via hydroxylation of collagen)
- Hypovitaminosis C
- Scurvy [[Proteins#1 Collagen]]
- Symptoms: sore and spongy gums, loose teeth, fragile blood vessels, swollen joints, anaemia due to defective connective tissues from not hydroxylating collagen
- Hypervitaminosis C
- Low toxic effects
- As it metabolises to oxalate -> Kidney stone risk in patients undergoing dialysis
38
What is FMN and FAD
Flavin mono nucleotide and flavin adenine di nucleotide
- Vitamin B2 (Riboflavin) is part of them
39
What is an ROS and what are free radicals
Reactive oxygen species (highly reactive molecule with oxygen in it)
Free radicals are extremely reactive atom with an unpaired number of electrons
40
What is thermic effect of food?
Energy needed for digestion, absorption, and metabolism of nutrients (~10% of TEE)
41
Main purposes of nutrients
1. Supply energy
2. For synthesis of molecules
3. Help metabolic pathways function
42
Describe the essential amino acids
PVT TIM HALL
- Phenylalanine, Valine, Tryptophan, Threonine, Isoleucine, Methionine, Histidine, Arginine, Leucine, Lysine (arginine essential for growing children)
- Proteins from animals contain all essential amino acids
- Proteins from plants contain some essential amino acids
43
Two types of minerals and what is a mineral?
- Macroelements -> required in quantities over 100mg/day
- Sodium, chloride, potassium, calcium, magnesium,
phosphate
- Microelements (trace elements) -> required in quantities
less than 100mg/day
- Iron, zinc, copper
- Minerals: an essential non-caloric inorganic nutrient needed in very small amounts in the body
44
Describe sodium, chloride, and potassium
- Function
- Maintain osmotic pressure
- Maintain pH
- Maintain nerve and muscle excitability
- Regulation
- By the kidneys regulate electrolyte and body fluid
levels and what stays and leaves body
- Disorders
- Deficiencies -> from increase in renal excretion,
vomiting, and diarrhea
- Excess -> specific causes
- Decrease sodium conc means body fluids are diluted -> excessive water -> brain swelling
- Increase sodium conc means less water
- Look at obsidian for disorders related to deficiency and excess
45
Describe calcium, phosphate, and magnesium
- Function: stored in matrix of bone and teeth
- Bone is reservoir -> degradation mobilises ions to
perform other body functions
- Calcium and Magnesium
- Contract all three types of muscles (skeletal,
cardiac, and smooth)
- Propogate nerve impulse
- Magnesium
- Important cofactor for enzymes using ATP
- ATP needs to form complex with it, deficiency
impairs all metabolism
- Calcium
- Blood clotting, hormonal signalling
- Phosphate
- DNA and RNA component
- ATP component
- Phosporylation
- Regulation
- Calcium and phosphate blood levels regulated by 3
hormones
- Calcitrol/1,25-dihydroxyvitamin d
- Parathyroid hormone
- Calcitronin (opposing effect)
- Look at obsidian for disorders related to deficiency and excess
46
Describe Iron
- Function
- Component of heme (redox rxn or bind oxygen)
- Heme containing proteins
- Haemoglobin and myoglobin -> binds oxygen -
> oxygen transport
- Redox enzymes -> proteins that function in
electron transport chain (eg. cytochromes) ->
energy metabolism
- Form complex with sulphur in proteins ->
component of complex I in electron transport chain
- Regulation
- High levels of hepcidin degrades ferroportin
- look at obsidian for disorders
47
Describe Zinc
- Function
- Contained in ~100 enzymes associated with
carb/energy metabolism, protein
synthesis/degradation, nucleic acid synthesis
- Not stored
- Deficiency
- Patients with major burns/renal damage
- Lost in dialysis
- Develop during intravenous feeding
- Affects growth, skin integrity, wound healing
48
Describe Copper
- Function
- Scavenges ROS reactive oxygen species
- Associated with complex 4 (cytochrome c oxidase) -
> affect ATP production -> affect heart as it needs a
lot of energy
- Deficiency
- Deficiency causes anaemia
- Plus cardiomyopathy in newborns
- Excess causes cirrhosis
49
What do we need to survive
- Survival importance: oxygen -> water -> nutrients
- Can survive w/o food for 60 to 90 days
- If patient unable to eat for more than 7 days, need
nutritional support
- Shorter for hypercatabolic patients
50
What is excess weight linked to
- Type 2 diabetes
- Cardiovascular diseases
- Cancers
- Liver diseases
- Respiratory diseases
51
Excess weight and covid risks
- Excess weight from nutrition and covid risks
- Positive test
- Hospitalization
- Advanced level treatment such as ICU and
ventilator
- Death
- Higher prevalence of covid complications
- Excess fat tissue and deposition reduce
respiratory function
- Fat has higher levels of ACE-2 enzymes
that covid virus latch onto and infect
- Inflammatory and immune response
- Thrombosis (blood clot blocking arteries and
veins)
52
Factors that determine nutritional status
1. Biological factors
- Genetic background
- Individual response to nutrients
- Nutrigenomics -> genes affect digestion,
absorption, metabolism, excretion, taste, and
satiety)
- Digestion, absorption, and excretion
- If digestion malfunctions, cannot go through
with later parts
- Age and phase of life cycle
- Difference physiological state across life
stages demands different nutrients
- Whether demands are met -> nutritional
status
- Last stage starts after 60
2. Psychological factors
- Satiety
- Appetite
- Palatability of food
3. Social Factors
- Availability of food
- Cultural customs/prohibition of certain foods
4. Energy expenditure
5. Presence of disease
53
Differentiate between anabolism and catabolism
- Chemical reactions that occur throughout the body within each cell
- Anabolism vs Catabolism
- Anabolism: set of metabolic pathways that
synthesize larger molecules from smaller ones
- Catabolism: set of metabolic pathways that break
larger molecules into smaller ones
54
Purpose of metabolism
- Purpose
1. Degradation of nutrients absorbed into the
intestines into simpler products
1. Can be used as precursors for synthesis of
new biomolecules
2. Can be disposed of via waste disposal
pathway if toxic or has no value
2. Generation of energy required for the synthesis of
molecules and body functions
1. Energy in form of ATP
