Nutrition Flashcards
What three actors influence nutrition
Environment (food)
Agent (diet)
Host (Body)
Burden of disease from poor nutrition
2 in 5 deaths
NZ obesity
~1/3 adults
Child obesity very high
Rationale for Eating Statement 1 “Variety of nutritious foods”
Need lots of different nutrients which you can only get from lots of different sources
Why are fruits and vegetables important
Vitamins C A K
Minerals
Fibre
Why wholegrains
Bran and germ contain FAR more nutrients/vitamins/fibre than the endosperm
Why dairy important
Calcium
Vit A K
Protein
Why legumes, nuts, fish, meat important
Protein
Iron and Zinc
Vitamin A, E
Fatty Acids
Where do NZers consume too much salt
Processed foods
Bread as despite moderate amount of sodium, it is eaten frequently in NZ
Why is eating statement 2 “Minimal sat fat, sugar, salt” important
These do bad things
Sat fat - obesity, cardiovascular
Salt - cardiovascular, renal
Sugar - cardiovascular, diabetes
Why is eating statement 3 “Water main drink” important
Water doesnt have high sugar etc
Hydration for renal
Why is eating statement 4 “Low alcohol” important
Alcohol bad for liver, cardiovascular
Why is eating statement 5 “store food safe way” important
Dont want bacterial infections from undercooking etc
Why are population guidelines and individuals different
Individual goals need to factor in cost, taste, culture, marketing etc
Specific goals eg Coelaic no wheat even though wholegrain wheat would be recommended for most people
Who is most at risk of malnourishment
Low SES
Elderly - can’t swallow all food types, harder to cook well etc
What are the two ways of taking a nutrition assessment
Habitual
Time-period
What is a time-period nutrition assessment
Intake in a specific time eg last 24 hrs
What is a habitual nutrition assessment
Standard intake, not based on any particular day
ABCDE of Nutrition Intake
Anthropometry
Biochemical
Clinical
Dietary
Economic / social
Anthropometry Things to check
The delta - weight, height, body composition changes including rate of chnage
Weight
Height
Circumferences - waist adults
- mid-upper arm children
Measuring body composition measures
Fatfold
Hydro density entry
DEXA
Bio electrical impedance
Air displacement
Drawback to fatfold body composition method
Assumes subcutaneous fat is proportional to total fat
Drawback to DEXA
Accurate but expensive
Drawback to hydrodensitometry
Estimate using volume calculations
BMI calculation
Weight / height-squared
Normal BMI
18.5-24.99
Obese BMI
Over 30
Different ethnic groups have different healthy BMI ranges?
Yes
- Asians lower
- Maori higher
When does change in body weight become significant
> 5.0% in 3 months
KEY POINT IS TIME INVOLVED
Biochemistry nutrition assessment
Blood and urine tests to check nutrients
Clinical Biochemical assessment
Signs/symptoms of deficiency/toxicity from physical examination
Oral and dental health
Medications
Where can you check malnourishment using fat
Pinching biceps region
- If no fat tissue = severe malnourishment
- If little fat = mild malnourishment
Dietary nutrition assessment
Estimation of dietary requirements and whether they’re being met
- Food and beverage intake
- Patterns of intake
- Supplements
- Food insecurity
Why are nutrition assessments important / used for
Malnourishment = high burden of disease
Used for determining if malnourished, making treatment plans, evaluating current interventions etc
What is the main source of energy for all ethnicities
Carbohydrates
- But different types eg potatoes Irish, Native American corn
Two principal types of carbohydrates
Complex or simple
Complex carbohydrates
Starches and fibre
Simple carbohydrates
Sugars (Di/monosaccharides)
Fructose
Monosaccharide from fruit
Galactose
Monosaccharide from dairy
Glucose
Monosaccharide that is rarely directly eaten, but made from conversion of other saccharides
Sucrose
Disaccharide that is “table sugar” ie main added sugar!
Lactose
Disaccharide dairy
Maltose
Disaccharide from fermentation (alcohol)
How are carbohydrates stored
Polysaccharides
- Glycogen = main human
- Starches = main plant, not made by us but consumed
Carbohydrate DIgestion in oral cavity
Mechanical - teeth
Chemical - salivary amylase breaks down starch
Carbohydrate digestion in stomach
None! As acidity deactivates amylase
Chemical Digestion in Small Intestine (Carbohdrates)
Pancreatic Amylase = further breaks down into small polysaccharides
Disaccharides ——> monosaccharide + glucose
X-ase (enzyme always X-ase eg sucrase acts on sucrose -> fructose)
Absorption of glucose
Active (Primary/secondary)
Absorption of fructose
Facilitated diffusion
Absorption of galactose
Secondary active
Fibre benefit
Protects against colorectal cancer, and other bowel health
How Microbiome impacted by nutrition
Specific nutrients associated with specific microbes = good gut
High glycaemic index carbs
Rapid rise in blood glucose / insulin in short-term
- Worse for diabetes
- Makes you hungry again soon
Examples of high glycaemic index carbs
Added sugar eg coke
Fruit (but fruit still healthy therefore not all high glycaemic bad)
Low glycaemic index carbs
Lower glucose and insulin spread over long time
- Better for diabetes
- Less hungry soon
Vit B12 Structure
Corrinoid ring (4 pyrolle rings)
Change to B12 (Cbl) in stomach
Binds to HC
=HC-Cbl
Change to B12 (Cbl) in duodenum
HC cleaved by pancreatic enzymes
Now can bind to IF
= Cbl-IF
Change to b12 (Cbl) in ilium
Absorbed
Types of B12
HC-Cbl = inactive, stored in liver
TC-Cbl = active, used in all cells
Deficiency of B12 results in
Macrosytic anaemia (pernicious aneamia)
Main cause of B12 deficiency
Lack of IF (required for absorption), rather than direct lack of B12
B12 dietary sources
Meat and animal products
People at risk of B12 deficiency
Vegans
- Vege fine since eggs, milk as well as meat
Requirements for B12 to bind to IF
R-binders
Panc enzymes
Pernicious Anaeamia
Autoimmune attack of parietal cells = not enough IF = not enough B12 = macrocytic aneamia
Pernicious Anemia Detetction
Autoantibodies of parietal cells
Other autoimmune conditions (as autoimmune conditions rarely isolated to just one)
Treatment of B12 malabsorption
Intramuscular injection
Schilling’s Test
- Radioactive B12 + INJECTION of B12 = saturated B12 = would expect in urine if normal
- Radioactive B12 + SWALLOW of B12 = saturated B12 = would expect in urine if problem is making=stomach, not in urine means absorption problem=ilium
What do proteins do
Energy
- Only when carbohydrate not sufficient
Enzymes, ion channels, transport, immune, structure etc
Essential Amino Acids number
9
Conditionally essential amino acid
Cant make in sufficient quantities under certain conditions therefore becomes essential
Non-essential amino acid
Synthesised by our body = dont need dietary intake
Protein percentage of energy intake
15-25%
Women recommended grams of protein per kilo per dag
0.75 g/kg/d
Men recommended grams of protein per kilo per day
0.84g/kg/d
Why do you need to do exercise to make protein intake help build muscle mass
If not then excess protein = excreted via urine
Are protein supplements useful
For most people no, only if malnourished or if intense exercise
Supplement important questions to ask
Safe
Legal
Batch tested
Work for me specifically
What is a complete protein
Has all/most of the essential amino acids
Animal proteins are more complete than plant
What are complementary proteins
Together they form a complete protein and have all/most essential amino acids
Protein Digestion pre-stomach
1 Cooking denatures protein
2 Mechanical digestion mouth
Moistened saliva
Protein digestion stomach
Pepsin (pepsinogen -> pepsin by HCl) breaks polypeptide into di/tri peptides
Protein digestion small intenstine
Broken into individual amino acids by pancreatic enzymes (trypsin, chymotrypsin, carboxypeptidase)
Tyypsinogen -> trypsin enzyme
Enteropeptidase
Chymotypsinogen -> chymotripsin enzyme
Trypsin
Procarboxypeptidase -> carboxypeptidase enzyme
Trypsin
What do trypsin, chymotrypsin, and carboxypeptidase do
Break di/tripeptides into individual amino acids = can be absorbed
Amino acid absorption small intestine method
Primary/secondary active into enterocyte
Fac diff into blood
What byproduct is produced during protein breakdown
Ammonia
How do we remove excess ammonia
Excretion urine
Positive nitrogen balance
Intake > exposure
= Growth
(Neutral) nitrogen balance
Intake = expenditure
Healthy adult that is not growing, pregnant etc
Negative nitrogen balance
Expenditure > intake
Starvation, cancer, burns etc
Nitrogen intake calculation
g(N) x 6.25 = g(Protein)
Calaculation for nitrogen balance
Grams excreted via urine sample
Grams intook via dietary measure of protein, then divide by 6.25
See if equal
Kwashiorkor
Diet deficient in protein (but sufficient energy)
= Muscle wasting, but preserved subcutaneous fat
Marasmus
Diet deficient in protein AND energy
= Severe muscle wasting, loss of subcutaneous fat as well
Most energy dense macronutrient
Fat (37 kJ/g)
Where do you get plant fats
Nuts and seeds
Short chain fatty acid length
1 to 6 C
Eg milk
How do trans fats occur
Not in nature, only byproduct of manufacturing
Saturated fats characteristics
Solid at room temp
Hard to spoil
Bad for heart
Unsaturated fats characteristics
Polyunsaturated liquid at room temp
Spoil more readily (unless hydrogenated = trans fat)
Essential fatty acids
Omega 3 and Omega 6
Omega 6 pro/anti inflammatory
Pro (which is good as we need ability to do acute inflammation)
Omega 3 pro/antiinflammatory
Anti (= good)
Why is the ratio of omega 3 and 6 important
They compete for the same enzymes to be converted into final form = important to ensure we are not saturating the enzymes with just one type
Final product of omega 3 and omega 6 conversion
Eicosanoids (direct cell action, not hormone)
Omega 6 conversion pathway
LA (vege oil) -> gammaLA -> AA (animal) -> eicosanoid
Omega 3 conversion pathway
ALA(veg oil) -> EPA (fish) -> DHA (fish) -> eicosanoid
Why do we need omega 3 and 6
Brain development
Vision
Inflammatory pathways
Do we need more omega 3 or omega 6
Absolute - omega 6
In NZ - more omega 3 to improve ratio
Ideal omega 3 to 6 ratio
1 Omega-3 : 2-4 Omega-6
Are sterols endogenous or exogenous
Both endogenous from production in our liver, exogenous from fish eggs and plants
Fat digestion in mouth
Mechanical
Release of lingual lipase (doesn’t do anything until pH activation)
Fat digestion stomach
Lingual lipase activated by pH
Gastric lipase
Muscle contractions disperse fat into smaller droplets
Fat digestion small intestine
Bile emulsifies fat into micelles
Pancreatic enzymes break emulsified fats down into monosaccharides, glycerol, fatty acids
If removed gall bladder how should you change your diet
No gallbladder = cant store bile, but can still produce
Therefore have smaller biles more often, and decrease fat intake
Why can micelles be absorbed but larger fat cant
Micelles small = sufficiently water soluble
What transports exogenous lipid
Chylamicrons CM
Endogenous lipid transported by
VLDL Very low density lipoprotein
What happens to CM when travelling around body
Shrinks in size and then eventually reabsorbed
Desired Energy intake from fat
20-35% total
trans/sat should be <10%
How is iron stored in the body
Ferrotin
Iron used in
Haemoglobin/myoglobin
Cytochrome P450 - metabolism of fatty acids
Iron transported in blood via
Transferrin
Iron absorbed where
Duodenum and proximal Jejunum
Can iron be excreted
Not easily - only by shedding intestinal cells that have iron stored as ferrotin
Iron in plants is
Only Nonheme
Iron from meat is
Heme and nonheme
How is heme iron absorbed
HCP1 into cell
Hox1 out of heme into Fe2+
How is nonheme iron absorbed
- Reduced to Fe2+ by DRA and Dcytb (in lumen)
- Absorbed by Dcytb and DMT1
How does iron get from absorptive cell into blood
Ferroportin channel (then into transferrin for transport)
Hepcidin function
Inactivates ferroportin = iron stuck in gut and can’t get to blood
Factors that enhance nonheme iron absorption
Vitamin C
Acid
MFP (in meat)
Factors that inhibit nonheme absorption
Phytates - bran
Tannins - tea
Dietary sources of iron
Meat, spinach etc
Contamination from cookware
Supplements
Fortification - cereal!
Who needs high iron
Women
Especially pregnant women
Growing children
Type of anaemic from iron deficiency
Microcytic
Stages of iron deficiency
- Depleted storage
- Iron restricted erythropoiesis
- Iron deficiency anaemia
Most common nutrient deficiency globally
Iron
What is the RDI
Level considered adequate to meet the needs of almost all healthy individuals (ie well above the estimated average requirement)
Water voluble vitamins
B and C
Fat soluble vitamins
ADEK
Excretion of fat/water soluble vitamins
Water - easy excretion via urine
Fats - less ready excretion, stored in fat
Absorption of water/fat soluble vitamins
Water - direct to blood
Fat - lymph then blood
Factors that affect Bioavailability of vitamins
Effieicny of digestion
Other foods consumed simultaneously
Food preparation method
Nutritional status
Synthetic/natural source
Vitamin B1 other name
Thiamine
Thiamine absorption site
Duodenum
Thiamine transport method
Active
Thiamine transport inhibitor
Alcohol
Thiamine sources
Whole grain - bran and germ which is removed in refined grains
Beriberi meaning
Thiamine deficiency
Wet beriberi impact
Heart failure
Wet beriberi chronic/acute
Acute
Dry beriberi acute/chronic
Chronic
Dry beriberi impact
Muscle wasting / neurological
Main cause of thiamine deficiency in developed countries
Alcoholism as transport inhibited
- Maybe we should supplement alcohol with thiamine
Vitamin B9 synonym
Folate
Folate function
Nucleic acid production and heart health
Cause of folate deficiency
High alcohol
Anti-inflammatory drugs
PREGNANCY
Why should we fortify with folate for everyone even though normally just when pregnant that defient
So much development happens before you know you’re pregant
Impacys of folate deficiency
Neural tube defects
Macrocytic anaemia
Vitamin D dietary source
Oily fish
VItamin D our own synthesis
Skin needs UV to convert to active form
Vitamin D function
Maintain plasma concentration of calcium to lead to increased bone density
Vitamin D deficiency impact child
Rickets
Vitamin D defiency impacy adult
Osteomalacia
Who needs Vit D supplement
People who have had bone injury eg surgery, trauma as increased metabolic demand
Drug-nutrient interactions
How long should you breastfeed
Exclusively 6 months
Continue for 2 years (or longer)
If adequate nutrition what changes during a babies first year
Massive weight increase
Length, head circumference, brain increase
Food security requires
Physical, social and economic access to nutritious and safe food
Low birth weight, or low growth as a child is associated with
Non communicable diseases later in life
Baby energy intake per kg compared to adult
Greater energy per kg needed
Why do people stop breastfeeding too early
- Back at work
- Social norms
Baby desired renal solute load
Low mOsm/L
Therefore breast milk is good, and better than formula
What nutrient do babies need the most
Iron
Which food groups are children lacking the most in
Fruit and veg
How should we compact childhood obesity
Dietary recommendations, physical activity
EARLY INTERVENTION - before school check
