exam Flashcards
what are the non- nutrients. are they beneficial, neutral or harmful?
Additives, pigments, alcohol, polyphenolics (beneficial, neutral or harmful, depending on how they’re consumed)
Steps to obtain primary data about contents of a food
- OBTAIN sample
- PREPARE sample (remove inedible parts/ prepare how it will be eaten)
- Create COMPOSITE SAMPLE
- ANALYSE the sample
24hr recall
- structures interview process
- quantitative
-time consuming for large groups
3- Pass Method
1st= quick list of consumed foods
2nd= collection of very detailed info.
3rd= Recall review- additional foods are added that have been previously forgotten
Adv: short time period, quantitative so more accurate.
Disadv: may misrepresent eating patterns, people alter diet from fear of judgement, incorrectly measured foods
History recall Technique
- 24hr recall
- note deviations from normal intake
- checklist of foods/ food groups
Adv: more info than 24hr recall, can focus on seasonal variation, see change in diet
Disadv: subjective, less valid as requires memory of longer time period
Food Frequency Questionairre
People indicate how much they eat certain types of foods and frequency
- Widely used in Australia
- questions focus on a 12- month period
Adv: good for groups, can be completed online, low burden if survey is short.
Disadv: different populations require different questions for accuracy, not good at capturing variation, language barriers may pose issue
weigh food record
Record everything consumed with scales
- most common method
Adv: high precision, low bias, can vary time period per participant
Disadv: people don’t carry scales around, laborious, people are likely to eat more measurable foods
Photographic Food record
Take photos of consumed food, often put beside a standardised object to compare size
Adv: Low burden, most people have cameras on their phones.
Disadv: combination foods are difficult to break down, difficult to estimate portion size
Direct observation
Watching people eat and recording what’s consumed
- uncommon
Duplicate Meals
Prepare two identical meals and recording the food eaten by comparing the difference in what’s left on the plate
- uncommon
Calorimetry definition and process
Method to measure the heat exchanged with surroundings
1. Homogenize food and dehydrate over 3 days
2. Dried samples -> pallets to be put in the calorimeter
3. Produced heat is measured and used to determine calories
Indirect calorimetry
- Basal metabolic rate (50-60% daily energy expenditure)
- Thermic effect of food (10%)
- Movement (10-35%)
Storage of macronutrients
Carbs- Glucose- glycogen
Fat- FAs- Adipose tissue
Proteins- AA- Prioritised as fuel (ATP)
Conditionally essential AAs
GAST- PC
Glutamine, Arginine, Serine, Tyrosine, Proline, Cysteine
Types of proteins
SETHS AC
Structural
Enzyme
Transport
Hormones
Storage
Antibodies
Contractile
Dietary Protein Quality
- determined by presence/ absence of all essential aa (out of 9)
- most foods that contain all= >90% absorbability
- foods that don’t meet criteria can be paired together as ‘complimentary proteins’
Biochemistry nutritional assessment
Laboratory analytical measured that can be made from biospecimens
- Iron studies
- Lipid profile
- Fluid/ electrolyte balance
- Blood+ glucose control
Oligosaccharides
3-10 sugar units bonded together
Polysaccharides
10< sugar units bonded together
Limiting Amino Acid
AA supplied in less than the amount required for protein synthesis
Glycemic response
Effect that food has on blood glucose concentration.
- Measure of this is known as GI
Glycemic Index
- Low GI food= <55, more slowly digested, absorbed, and released into the bloodstream. - Medium GI foods, 55-70
- High GI foods= >70, rapidly released into the bloodstream.
Minerals
- Inorganic, individual elements that can be ingested from food either as individual charged ions, mineral salts or mineral acids.
- On dissolving in water, the mineral salts and acids will ionise
- regulates water distibution
- Major, trace, non- essential
Bioavailability
Rat ate which, and the extent to which, a nutrient is absorbed and used.
- the rate of digestion and absorption of a nutrient
Influences:
- GI tract transit time (speed of bolus/ chyme)
- GI tract integrity ( if tract is damaged)
- presence/ absence of other nutrients
- food prep and storage
Nutrient content claims
Claims about the content of certain nutrients or substances in a food, need to meet specific criteria in the standard (≥25% of the RDI in one serving).
General Health Claims
claims abt a nutrient/ substance in a food+ its affect on health.
E.g calcium is good for teeth
High level health claims
claims abt a nutrient/ substance in food+ its relationship to a serious disease/ biomarker
phytochemicals
- non- nutrient for plants
antioxidant, mimicking action of hormones etc.
alkaloids
- bitter- tasting, widespread.
- made into nicotine, caffeine, morphine, coke etc.
- used in some cancer treatments
phytosterols
- plant-based molecules similar to cholesterol
- helps lower risk of CV disease as they can bind to GI tract receptors= inc. cholesterol digestion
antioxidants
molecule that can give energy to a ‘free radical’
Vitamin C enhances absorption of _____.
Iron
helps convert Fe3+ to Fe2+, which is absorbed by the small intestine through the DMT1 channel.
Also helps Fe2+ stay in that form, allowing more non- haem iron to be absorbed.
Vitamin D enhances absorption of _____.
calcium, phosphorus, magnesium
- in Vitamin D deficiency, less that 15% Ca from food is absorbed (adequate Vitamin D =30-40%)
Dietary fibre reduces absorption of ________
some minerals and cholesterol
calcium intake reduces absorption of ______
Iron
calcium temporarily affects ferroportin transporters (allows iron to enter circulation)
phytosterols reduce absorption of ____
Cholesterol
Fat, protein and acid reduce the rate of _______ absorption
Carbohydrate
F+P in bolus= dec. rate of gastric emptying
- acid reduces GI (food and stomach)
Alcohol reduces the absorption of ________
many nutrients
- causes inflammation to cells lining GI tract= dec. absorption of B6, B12, folate, zinc, magnesium and calcium
how do macronutrients affect energy metabolism
- The relative amount of each macronutrient in the diet can influence the amount of each that are used for ATP production
- if very little C are eaten over a week= dec. production of enzymes which metabolise glucose+ inc. amount for FA metabolism.
how does selenium, iron & iodine intake affect thyroid function
Selenium+ iron= required for the thyroid gland to produce hormones (T3+T4). so deficiency= risk of iodine toxicity as it cannot be incorporated into thyroid hormone
How does Vitamin E intake affect Vitamin K
overconsumption of E interferes with the roles of K (blood clotting)
how does folate affect B12
B12 required to convert folate to active form, so deficiency of B12 can= folate deficiency as well.
how does Magnesium affect vitamin D
Mg is required in the liver for the action of enzymes which activate D3. so Mg deficiency= Vitamin D deficiency
high protein intake and calcium excretion
protein metabolism= slight increase in body acidity= inc. breakdown of bone mineral w Ca lost in urine
- bone is made up of proteins +minerals, both are required for strength and rigidity
how does sodium intake affect Calcium excretion
high Na diet= reduced reabsorption of Na (usually means higher food intake so no increase in bone loss)
high Na, low Ca diet can= reduction in bone health
