Dietary assessment Flashcards
What are the four main methods of dietary assessment?
- 24 hour recalls
- Diet record
- FFQ
- Diet history
Why use dietary assessment?
- Examine nutrient intake
- Look at specific foods/ food groups
- Examine dietary patterns
___ in ____ toddlers are iron deficient
1 in 3
How much can fortified milk increase toddler’s iron status by?
~122% (though subconsciously reduced red meat)
How do you carry out a dietary assessment recall?
- Develop a quick list
- Probe for forgotten foods
- Obtain food details (cooking method, time, brand)
- Obtain portion size (familiar measures)
- Final review (last chance to collect info on food not remembered)
What is the goal of a 24 hour diet recall?
Capture actual intake over a pre-specified time
What different types of diet recalls are there?
+ paper or online
+ can use interviewer or self-administered
What are the limitations of a diet record?
- have to carry measuring equipment & diet record
- have to ask about contents of food
- may change way someone eats
What is a food frequency questionnaire used for?
To measure usual or habitual intake (assess the frequency of intake of certain foods & look at specific dietary sources of nutrients)
What is one important consideration to take into account when when carrying out FFQ’s?
Must be validated for population it is going to be used in.
What is a diet history?
A fact to face interview (similar to a diet recall) that asks about variations over a week to help gain understanding of someone’s usual intake.
What is a diet history usually evaluated against
Recommended servings (i.e. of alcohol & salt)
What are key things to consider when conducting a dietary assessment?
- All responses are confidential
- Be non-judgemental
- Do not ask leading questions (portion sizes, breakfast etc..)
- Accuracy of information is very important
What are sources of error in a dietary assessment?
+ Change what you report (interviewer judgemental)
+ forgot what you ate
+ hard to estimate portions
+ raw/cooked weight?
+ ignoring drinks
+ people not volunteering cause not interested (bias)
+ unsocially acceptable cause misrepresentations
What are food composition databases?
+ average nutrient content of wide ray of foods
+ NZ Foodfiles
What is validity?
The extent to which a method gives you the “correct” answer
What is the difference between relative & absolute validity?
Absolute requires precise measurement of intake, whilst relative validity is indirect.
What is Reliability/ Repeatability?
The extent which a method gives you a reproducible answer
What is accuracy?
Accuracy is the e extent to which the measurement is close to the true value
What is measurement error?
Difference between measured & true value
What is observed intake?
True intake + measurement error
What are the 2 types of measurement error?
Random & systematic error
What does measurement error lead too?
Attenuation of relationships & Bias
What is random error?
Error due to chance/ normal variation which leads to increased variability around the mean & decreased variability
(Doesn’t change Mean)
What are some sources of s error?
a) Non-response bias
b) Respondent bias
c) Interviewer bias
d) Respondent memory lapses
e) Incorrect estimation portion size
f) Omission of supplements
g) [Coding and computation errors]
h) [Errors in handling mixed dishes]
i) [Errors in food composition database]
What is non-response bias?
When a specific sub-set of people don’t volunteer to participate, adhere to the intervention or drop out.
What does non-response bias cause?
A non-representative sample (under/ over estimates effect)
What are some strategies to minimise non-response Bias?
- Minimize respondent burden
- Mail or phone reminders
- Offer material rewards
- Train interviewers so warm and trusted
- Identify non-responders and characterize
- Over-sample groups at risk of non-responding
What is Respondent Bias & the three main types?
Bias introduced by the Respondent
- Low energy Reporting
- Over reporting
- Social desirability
What are some strategies to minimise respondent bias?
• Pre-test methods (cognitive interviewing?)
• Interviewer training
• Private interviews
• Identify flawed data (e.g. Goldberg equations)
• Identify participants at risk:
Ø Social desirability scale
Ø Dietary restraint scale (e.g. Eating Inventory)
What is interviewer bias & the 3 main causes?
Bias introduced by the interviewer Caused by: \+ Incorrect recording \+ intentional omissions \+ poor cultural sensitivity
What are some strategies to minimise interviewer bias?
Strategies: • Standardized computer interviews • Train interviewers: Ø Avoid value judgments Ø Culturally safe Ø Pace • Identify problem interviewers: Ø Multiple interviewers same interviewees Ø Mean energy intake per interviewer
What are respondent memory lapses?
- Errors of Omission
2. Errors of Commission
Who is respondent memory lapses more likely in?
- Longer time period to be recalled
- Men
- Age extremes
- distracting environment
What are strategies to minimise respondent memory lapses?
Multiple-pass interviewing techniques
Ø Free uninterrupted recall
Ø Probe questions
• Minimize time between intake and recall
• Work with information retrieval, e.g., <8yrs of age:
Ø Visual imagery
Ø Usual practice
What is incorrect portion estimation?
Failure to accurately quantify amount eaten
What is the largest source of systematic error?
Incorrect portion estimation
What are strategies to minimise incorrect portion estimation?
- Measurement aids:
- Train interviewers
- Train respondents
What does supplement omission lead too?
Systematic underestimation of nutrient intake
Ø Overestimation of prevalence inadequacy
What are strategies to minimise supplement omission?
• Structured questionnaire on long-term intake • Close-ended questions on: Ø Brand Ø Amount per pill Ø Frequency of use Ø Duration of use Ø Chemical form of supplement • Interviewer sights supplement
What is sensitivity?
How good the test/method is
at correctly identifying people who have the
disease/low status
What is specificity?
How good the test/method is
at correctly identifying people who are
well/have adequate status
What are sources of error in portion estimation?
- Memory/recall • Incorrect use of portion size tools (Interviewer)
- Quantification skills of respondent
- Density factors
What cognitive processed effect portion size estimation?
- Perception- amount in relation to aid
- Conceptualization- amount not present
- Memory
PLUS
• Social desirability
What are some portion size estimation tools?
- Household measures
- Standard measurement units: g, kg, ml, ounces, pounds
- Known packaging size
- Visual aids e.g. diagrams, photos, food atlas
- Categorical size estimations: small, medium or large
- Food models
- Hands
- Beans, water- measuring cylinders
What are different ways diet recall can be administered?
+ in home; clinic; school; or workplace
+ Interviewer administered/ self-administered
+ Computer based self- administered recalls
What factors influence portion size estimation?
- dietary assessment method
- Type of Food
- Respondent characteristics
What is the recipe dilemma?
- Ingredients
- Quantities • Before cooking
- Yield after cooking
- % consumed by participant
- Only Part eaten?
What is the flat slope phenomenon?
Large portions are underestimation & small portions are underestimated
_______ food is more difficult to estimate than single unit food
Amorphous
consumers estimate ______ portion size if the packet is larger
Larger
What respondent characteristics influence portion estimation?
Ethnicity/ culture (shared dishes; different utensils; eat with hands)
Literacy & numeracy
Age (memory & cognitive development)
How does literacy effect serving size?
High literacy increases accuracy 2.5 x
Why does food not always = nutrients?
Personal & broader meanings to food that we are often not aware of
What do the meanings we associate food impact?
What, how & when we eat
What are the implications behind food meanings?
May impact accuracy
+ food composition data may be unreflective
+ habitual or regular intake?
+ may provide substantial amounts of nutrients
+ focus on people during events so poorer recall
+ weighed food record = intrusive
Respect
+ need to be aware of occasions & only obtain essential data
What is bioavailability?
The proportion of a nutrient
in a food that is digested,
absorbed and utilised
How much non-haem iron is absorbed?
5-15%
How much iron is lost daily?
1mg/day (men)
2mg/day (women)
What are men & women’s iron requirements respectively?
~ 8mg/day; 18mg/day
Where is iron lost?
Epithelial cells: – Skin (~0.2mg) – Intestinal mucosal cells (~0.1mg) – Urinary tract cells (~0.1mg) • Fluids: – Blood (gut (~0.4mg), menstruation) – Bile (~0.2mg)
What is bioavailability influenced by?
- Chemical form of nutrient
- Food composition
- Meal composition
- person’s nutrient status
- Physiological status of person
- Amount consumed
Why do we measure bioavailability?
- Nutrient Reference Values set using %
absorption from typical diet - Identify & quantify new “enhancers” and
“inhibitors” of nutrient absorption - Compare efficacy of new supplements
- Develop algorithms to estimate absorption
What are isotopes?
same number of protons
different number of neutrons/ mass
What are radioisotopes?
Atoms with an unstable nucleus that emit alpha particles, beta particles & gamma rays during radioactive decay.
What are emissions of radioactive decay responsible for?
Ionising radiation –> removal of electrons from atoms, which damages tissues
What is the difference between alpha, beta and gamma particles?
Alpha particles (α) - Low penetrating power - Cause high ionisation Beta particles (β) - More penetrating than alpha - Not as ionising as alpha Gamma particles (γ) - High penetrating power - Causes least ionisation
What are radioisotopes used for?
• Balance studies admin dose – faecal (+ urine) losses • Whole body counting • Plasma appearance • Hb incorporation (for Fe)
What are advantages of radio isotopes?
- True tracers
- Often cheaper than stable isotopes
- Minimal sample preparation needed
What are the disadvantages of radio isotopes?
• Radiation dose (research doses ~ X-ray exam, or long-distance flight)
• Cannot be used with pregnant or lactating women, infants
or children
• Ethical approval only possible in certain countries
What are stable isotopes?
Naturally occurring isotopes that do not emit radiation
How are stable isotopes used?
• Balance studies
admin dose – faecal (+ urine) losses
• Plasma appearance
• Haemoglobin incorporation (for Fe)
What are the advantages of using stable isotopes?
+ No known health effects
• Can be used in any population
• Multiple isotopes (for Fe)
What are the disadvantages of using stable isotopes?
- Expensive – isotopes, equipment, time
- More sample preparation
- Need larger doses
- Only 1 stable isotope for iodine so can’t study absorption
What is the chemical balance equation to measure bioavailability?
Apparent Fe absorption = Fe intake – Faecal Fe
What are the advantages of using chemical balance equation?
- Whole diet not single meals
- No radiation
- Several nutrients at once
What are the disadvantages of using chemical balance equation?
• Large margin of error (can use faecal marker) • Nutrient retention may depend on status (some nutrients) • No correction for endogenous excretion (e.g. Zn)
What are algorithms?
Mathematical equations that Use intakes of selected enhancers and inhibitors to
estimate % of nutrient absorbed & assume a specific nutrient status
What are the advantages of using algorithms?
Quick + inexpensive
What are the disadvantages of using algorithms?
Underestimate absorption (Beard et al, 2007)
• Need food comp data for components not in FOODfiles
• Don’t account for interactions between abn modifiers
• Effects based on single meal not whole diet studies
Define EAR?
Estimate adequate requirements: meets the requirements of half the healthy population
Define RDI?
Recommended dietary intake: sufficient to meet 97-98% of the healthy population’s requirements
What is AI?
Adequate intake: assumed adequate intake of healthy population from observations
What is UL?
Upper limit: highest intake with no adverse heath effects
What are the uses of nutrient reference values?
Assessment and surveillance – Individuals and groups (L11-L12) • Planning diets – Individuals and groups • Inform policy • Education • Food labeling and marketing • Emergency food aid
What are the 3 main sets of recommendations?
• Nutrient Reference Values (NRVs) = Australia and New Zealand • Dietary Reference Intakes (DRIs) = United States and Canada • Dietary Reference Values (DRVs) = Europe
What is a physiological requirement?
The quantity of a nutrient needed by the
body to maintain a particular level of
function.
How do you determine physiological requirements?
+ Factorial estimation
• Depletion/repletion study
• Animal studies
What are physiological requirements influenced by?
• Physiological factors • Lifestyle factors • Biological & genetic factors • Environmental factors
How are EAR’s established?
- determine distribution + average physiological requirements (+ SD)
- Adjust for bioavailability & bioconversion
How is an RDI set?
RDI = EaR + 2SD
IF UNKNOWN ASSUME SD = 10
If there is no-observed-adverse effect level to determine a UL, what is used?
Lowest-observed-adverse-effect level with uncertainty factor
When is a larger uncertainty factor?
To animal data & when over-consumption has serious effects
Why is an uncertainty factory applied to UL or nutrient value?
• Limited data on distribution of physiological
requirements
• Data are mainly for young adult males
• Limited absorption data for different diet types
• Limited data on usual food intakes
• Limited data on interactions between nutrients
• Limited data on influence of host-related factors
What is the underlying assumptions when setting a nutrient reference value?
• Population is healthy • Nutrient intake is usual intake • Requirements for energy and other nutrients are being met • Nutrient requirements and intake are not correlated
What are 4 forms are nutritional assessment?
- Anthropometric assessment
- Dietary Assessment (nutrients & Dietary Practices)
- Biochemical Assessment
- Clinical assessment
What are appropriate uses of NRV’s?
Ear: used to examine probability adequeate
RDI: if this is usual intake -> level has low probability of inadequacy (qualitative)
AI: above AI = low probability of adequacy
UL: If above have high probability adverse effects
What is apparent adequacy?
estimate of one’s confidence is above or below own requirement
What is the quantitative approach to determining nutrient adequacy?
Calculate mean intake & find estimation of day-to-day variation
What reference standard should you use when determining nutrient adequacy?
EAR
How do you determine difference in intake vs requirements?
Difference = mean observed intake – median requirement
How do you determine SD of nutrient inadequacy?
SD of difference = (variance of distribution of reqs in groups + average variance in day-to-day intakes of nutrient/ no of days of intake))
How do you determine nutrient adequacy?
Difference/ Standard deviation of Difference
What is required to determine nutrient adequacy?
- Mean observed intake
- EAR
- Standard deviation of requirements
- Variance of requirements
- Standard deviation of day-to-day intakes
- Variance of day-to-day intakes
- No of days of observed intake
A value below the ___ cannot tell us anything the nutrient adequacy (only can determine adequacy above AI)
Adequate Intake
What is a qualitative approach to determining nutrient adequacy?
Assumes requirements & intakes are normally distributed
What is the qualitative approach to using EAR to determine nutrient adequacy?
+ Observed intake is less than EAR (50% probability need to increase)
+ If RDA is long term more than observed intake probs need to increase
+ If long term intake > RDA Probs adequate
What is the qualitative approach to using AI to determine nutrient adequacy?
If long term intake > AI = probably adequate (less cannot determine)
What is the qualitative approach to using UL to determine nutrient adequacy?
Observed intake > UL = risk over a large number of days (safe if not)
What are the limitations of determining nutrient adequacy using a qualitative approach?
+ Don’t have actual usual intake or actual requirements
+ Assume coefficient of variation = 10% for SD(requirement)
+ Assume SD (intake) is similar to pooled data
+ Assume no low energy reporting
+ Don’t have EAR for all nutrients
Why is information on group intake important?
- monitor population intakes
- Identify problem nutrients
- Plan programmes to address problem nutrients
- Need to know appropriate methods to decide whether to believe/ use papers you read
Ear is used to estimate the _________ of inadequate intakes within a group
Prevalence
UL is used to estimate _______ of population at risk of adverse effects
percentage
What is the EAR cut point method?
- Collect 2-3 days
- Adjust intake distribution (remove day to day variability)
- EAR cut point method (prevalence of inadequacy proportion of intake < EAR)
What does EAR cut point method assume?
+ no correlation between intakes + requirements
+ distribution of requirements is symmetrical
+ variance of intakes > variance in requirements
+ Prevalence of inadequate intakes is neither very high nor very low (10%-90%)
What is the issue with the EAR cut-point method?
+ straight line leads to false negatives & positives as individual requirements different (false neg = false positives cancel out)
What is the probability approach to determining nutrient adequacy?
Determines the weighted average of risks at each intake level
What does the probability approach assume?
there is no correlation between intakes & requirements
How do you determine nutrient adequacy using the probability approach?
- Construct risk curve
- Determine % of intakes in each risk category
- Determine prevalence of inadequacy
What % of the population has inadequate iron intake?
43%
What nutrient reference value can you not use to determine nutrient adequacy?
AI
What are the limitations of qualitative approaches to determine nutrient adequacy?
- Can’t use EAR cut point method people with inadequate intake (just groups)
- Time consuming to calculate (full prob approach)
- Don’t have EAR for all nutrients
What should you NOT do when determining nutrient adequacy?
- Compare mean intakes to EAR or RDA
- Use Ear cut point method to asses iron intake in premenopausal women
- Use EAR cutpoint method for small groups (<30)
- Use the proportion of the group < RDA
- Forget to adjust for day to day variation in intakes
What is the aims of food based dietary guidelines?
to promote overall health, control
specific nutritional diseases …, and reduce the
risk of multifactorial diet-related diseases
What are food based dietary guidelines specific too?
– Ecological setting
– Sociodemographic profile
– Customary dietary patterns
What are some food based dietary guidelines used to assess diets?
Healthy Eating Index (HEI)
– US dietary guidelines
• Healthy Diet Indicator (HDI)
– WHO dietary guidelines for prev chronic disease
• Mediterranean Diet Score (MDS)
• Dietary Approaches to Stop Hypertension
score (DASH)
What are the guiding principle of the healthy eating index?
- simple as possible
- limited number of components
- no single food = essential
- focuses on quality (not quantity)
- doesn’t assess supplement intake
How is the healthy eating index interpreted?
Radar graph
What positive health outcomes are the healthy eating index, alternative healthy eating index & DASH diet associated with?
Reduction in the risk of CVD, cancer & type 2diabetes
What are diet apps?
applications that allow users to
enter their food intake and match foods to large nutrient
databases.
What are the main advantages of diet apps?
+ Food is entered at the time it is consumed.
+ Can provide reminders
+ You need little training
+ Accessible with the right resources
+ Save time and money as food is not manually coded
+ Allow individuals to self monitor their diet
+ Discrete
What are the disadvantages of diet apps?
+ Large variations in relative validity
+ Users enter foods
+ Limited food descriptions
+ Not all foods in the nutrient database
+ Nutrient data missing
+ Usually limited to the nutrients on the NIP.
+ Nutrient database not from NZ
+ Limited capacity to add recipes - no nutrient retention factors
+ Users may have limited knowledge of food composition and data
entry
+ Information may be difficult to interpret
+ Assumes you follow regular dietary patterns
What nutrients must the NIP panel contain?
\+ Energy \+ Carbohydrate \+ sugar \+ Fat \+ Saturated fat \+ Protein \+ Sodium
What is the issue with goal intakes?
+ Everyone’s energy requirements are
different.
+ EER set at average requirement
+ Chances of your ‘goal’ energy intake being
right for you is low
+ BMI/ weight trends is the only way you can
tell if you energy intake is adequate.
What is self-monitoring strongly correlated with?
weight loss & facilitated behaviour change
What are concerns with diet apps?
+ use in children
+ use in perpetuating eating disorders
What questions should we ask when using diet apps?
+ Who is using it (age; level of food knowledge; digital literacy)
+ What are they using it for (level of accuracy required & what nutrients are important)
What is the Low energy reporting?
- Under-reporting: deliberate/ unintentional; omission/ underestimation of foods
- Under-eating: process of reporting make people change their eating habits (eat less than usual)
What are mean energy intake of males & females aged between 19 & 30.
males: 11.9 MJ
females: 8.4 MJ
How can we identify low energy reporters?
- Doubly labelled water
- Indirect calorimetry
+ Douglas bag
+ On-line gas analysis
+ Portable gas analysis
HOW does doubly labelled water estimate low energy reporters?
- Mesures oxygen-18
& estimates CO2 production
to assume energy balance
HOW does indirect calorimetry estimate low energy reporters?
Determine how much energy is metabolised based on oxygen converted to CO2
What are the steps of doubly-labelled water?
+ drink water with isotope
+ metabolism produces water & CO2 in urine
+ Hydrogen is expelled in urine while Oxygen is expelled in both
+ Ploy enrichment over a time period
+ Hydrogen - oxygen shows how much CO2 produced
+ CO2 is a result of metabolism of macronutrients
What are the advantages of doubly-labelled water?
+ once co2 losses determined can calculate total energy expenditure
+ if in energy balance energy intake = energy expenditure
+ very accurate & simple
What are the disadvantages of doubly-labelled water?
+ very expensive
+ Only get average energy expenditure
+ Assumes in energy balance
What are the 3 steps of using doubly-labelled water to identify low energy reports?
- Collect dietary data
- Measure energy expenditure
- Calculate difference
How can we use equations to estimate doubly-labelled water?
Based on estimated basic energy requirement
Goldberg equation allows to determine if intake is plausible
Lower than habitual intake cut-off is lower
How do we use the Goldberg equation?
- Collect energy intake, sex, age, weight
- Calculate estimated BMR using Schofield et al (1985)
- Use Goldberg et al (1991) to determine the cut-off value for 1 person with data collected
- if EI: BMR is under cutoff = underreporting
What are the advantages of using the Goldberg equation?
quick, easy, cheap
Do it respectively (If have age, sex, weight)
Non-invasive
What are the disadvantages of using the Goldberg equation?
Not as accurate as DLW
Assumes sedentary
Assumes in energy balance
misses people with high intakes that are underreporting
How should low energy reporters data be dealt with?
Either exclude or report prevalence
What are biomarkers?
Substance in biological specimens that reflect intake sufficiently to act as objective indicators (fatty acids, nitrogen etc)
Why do we use biomakers?
+ independent of many errors (can assess measurement errors)
+ can use to calibrate measurement error in dietary data
Why do we not use biomarkers instead of dietary assessment?
+ Only available for some nutrients
+ Expensive
+ Invasive (biological specimens, complete collection required & multiple collections may be required)
+ transport & storage issues
What assumptions behind using biomarkers?
+ assumes energy balance
+ 24hr urine nitrogen assumes nitrogen balance
Don’t capture total intake:
+ reflect recent intakes only & may be affected by disease states
What are sources of bias when carrying out dietary assessment?
- Non-response bias
- Interviewer bias ( UNLIKELY may cause incomplete collection)
- Coding & computation errors
- Day to day variation in diet & biomarkers
- Changes in diet over time
- Changes in diet due to overestimation (unlikely)
What is the main issue with the treaty of waitangi?
Major differences between maori & English version (initially written in English & poorly translated)
Why do we need to know about the treaty of waitangi?
Need to know about it to act in a professional way moving forward
What are the main ideas behind the treaty of waitangi?
+ Partnership: working with Maori & communities to develop strategies & services
+ Participation: Maori should be involved in all levels of health & disability sectors including decision making, planning & service delivery
+ Protection: ensuring Maori have the same level of health as non-Maori & safeguarding their concepts, values & practices
Why is their urgency to enact protection, partnership & participation?
Maori are typically severe disadvantaged
What is the difference between equity & equality?
Equality is an equal opportunity is same step up (if initially disadvantaged still disadvantaged)
Equity: people who need help are given it so everyone is at the same level
What is a consultation?
Setting a proposal not fully decided on and adequately informing a party about relevant info, adequately informing a party, listening to others input, genuine
Proposal MAY or MAY NOT alter the original proposal
What is engagement?
Attracting & involving someone’s interest (groundwork which a meaningful consultation can be undertaken)
How do we start engagement with maori early?
+ Find someone with connections with local iwi
+ emphasis on partnership beyond specific project
+ consider capacity & capability building of maori researchers (help upskill)
+ Consider tikanga (differs by iwi) important for someone with connections to guide you
+ convey information clearly in plain English
+ face-to-face interactions valued
+ Ensure entire team is aware of responsibilities to maori
+ disseminate results in a way that benefits maori
What is good practice when consulting with maori?
+ introduce yourself
+ aske how to pronounce Maori names
+ offer verbal administrations rather that written administrations
+ allow whanua to be present
+ explain what & why doing something & ask for permission to preceed
+ ask before touching head (tapu)
+ only ask participant to remove hair ornaments if essional
+ keep biological samples in a separate area than food
+ offer participations the option of karakia
+ never sit/ lean on tables/ desks
Pai definition?
to consent
Hiakai definition?
Hungry
Hiainu definition?
Thirsty
Hiamoe definition?
tired
Hoha definition?
bored, tiresome, fed up etc..
Pukumahi definition?
Hard working (informal: busy)
What is the goal around Te-reo language?
1 million people able to hold a convo in te-reo by 2040
What are lab methods of assessing nutrient status?
Static biochemical tests & functional tests to detect subclinical deficiency & confirm clinical diagnosis
What is a static biochemical tests?
Measures urinary excretion rate of nutrient/ metabolites (as there are nutrients in biological fluids & tissues)
What are functional tests?
Functional Biochemical tests: Measures of activity of enzyme
Functional physiological & behavioural tests
What is precision?
Repeated measure on pooled samples (coefficient of Variation) CV = SV/ Mean
Just shoes consistency
What is analytical accuracy?
recovery tests on spiked samples, certified reference materials & analysis of poled sample by multiple labs (proves assay is correct & consistence)
What is analytical sensitivity?
minimum detection limit
What is analytical specificity?
ability of method to exclusively measure the substance of interest (using dry ashing or wet digestion)
What is validity?
extent to which a test is correctly reflecting nutritional parameter of interest (drugs, hormones, infection may alter lab test results)
What is predictive value?
Ability of lab test & cut-off to predict presence/ absence of disease
Why is the difference between venous & capillary blood?
- Measure different amounts of nutrients
- Haemodilution can occur if squeeze finger (capillary)
- Easier to provide a capillary sample; less individual burden; quick; less painful/ invasive
Whats the difference between plasma & serum blood?
- Plasma contains fibrinogen
2. serum doesn’t contain fibrinogen
What are the different requirements for different assays?
+ Use Navy (trace element free evacuation tube) & stainless steel needle for zinc (common in environment)
What do you need to take into account when carrying out biochemical tests?
+ pay attention time of day, mealtime & symptoms
+ Pay attention to acute phase proteins that tell about infection
+ Standardise analytical correct for time of day & meal time
What are some precautions to avoid zinc contamination?
+ polyethylene gloves
+ processed in laminar flow clean rooms
+ pre-screen and use polyethylene processing & storage vials
+ need to be stored while sealed
What are the 5 main functions of iron?
- Oxygen carrying & storage
- Oxidative production of cellular energy
- Glycolysis in muscles
- Serotonin & Norepinephrine production
- Neutrophil function
What are the symptoms of iron deficiency anemia?
\+ poorer work & exercise capacity \+ fatigue \+ behavioural disturbances (clinginess \+ decreased cognitive function \+ decreased growth \+ spoon-shaped nails
What are the symptoms of non-anemic iron deficiency?
May have poorer cognitive function, fatigue, low mood, reduced work capacity
Increase risk of iron deficiency anaemia
What is the aetiology of iron deficiency?
Low intake/ poor absorption High requirements (growth, blood loss & pregnancy)
What 6 groups are at risk of anemia?
- Infants (esp. premature)
- Toddlers (~30% suboptimal Fe)
- Menstruating women (`13%)
- Pregnant women
- People experiencing Blood loss
- Vegetarians
How do we assess iron?
Through Biochemical assessment
What is the pathway of iron absorbtion?
- Iron is absorbed into the epithelial cells (10-15%)
- Iron moves into circulation bound to transferrin
- Iron Travels to erythrocytes where RBC are formed
- Haemoglobin undergoes phagocytosis (most ferritin retained)
- Lose haemoglobin through bleeding
What are some red cell indicies?
Haemoglobin Haematocrit: packed cell volume (proportion of cell made up of RBC) Mean cell volume = HT/ RBC Red cell distribution width Erythrocyte proporphyrin (immature Haem)
What can we measure to determine iron status?
- Serrum iron
- serum ferritin
- transferrin saturation
- iron binding capacity
- no. Serum transferrin receptors
What are the 3 stage of iron deficiency?
Stage 1: depleted stores -> NO RBC protected
Stage 2: Iron deficient erythropoiesis: starting to impact RBC
Stage 3: Iron deficiency erythropoiesis: dropped number RBC -> haemoglobin drops
What stages are serum ferritin decreased?
Depleted in all stages
What stages are transfferin saturation depleted in?
Depleted in stage 2 & 3
What stages does FEP increases in?
Increases in stages 2 & 3
What stage does HB deplete in?
Stage 3
What are cut off & references?
Statistical parameters of population distribution (rarely know cut-offs)
What is the reference limit for HB?
<120g/L (children have lower cut off); men have higher cut-offs than women (130ish)
What is the reference limit for mean cell volume?
<80fL
What is the reference limit for FEP?
> 80mol/mol haem
What is the reference limit for Transferrin sat ?
<15%
What is the reference limit for serum ferritin ?
<12ug/L
How do we define iron deficient erythropoiesis?
2+ of SF, TS & FEP are abnormal & Hb is normal
How do we define iron deficient anaemia?
2+ of SF, TS & FEP are abnormal & Hb is low
What is the body iron model?
Equation based on ration of serum transferrin receptor & serum ferritin
What does a body iron per Kg under 0 mean?
Iron deficiency
What does a body iron per Kg under 0 combines with low Hb mean?
iron deficiency anaemia
What are the advantages of using the body iron model?
Good estimate of body iron measured by phlebotomy
Continuous variable
Less affected by inflammation
What are the advantages of using the body iron model?
Cost sTfR
No standard method sTfR
What are the 3 types of iron overload?
- Acute iron toxicity
- Hereditary haemochromatosis
A3. frican Iron overload
What is Heredity haemochromatosis?
+ Autosomal recessive condition
+ Poor control of iron absorption
+ iron accumulates in liver, pancreas, heart muscles
+ Treatment very effective if started early
What serum ferritin levels indicate haemochromatosis or iron overload?
> 300 ug/L males
> 200 ug/L females
What serum transferrin saturation levels indicate haemochromatosis or iron overload?
> 55% men & post-menopausal women
> 50% in premenopausal women
What are the uses of iron status indicators at the individual level?
Screening & clinical assessment
What are the uses of iron status indicators at the Population level?
+ Prevalence estimates of deficiency
+ Planning appropriate interventions
+ Evaluating impact of interventions
if iron is on the cut off it counts as deficient at the ____ level & sufficient at the _____ level.
Individual
Population
What are the indicies used for clinical assessment of iron status?
Hb
serum ferritin
C-reactive protein
transferrin saturations
What does C-reactive protein show us?
Use presence of infection
What is the issue with Hb reference limits?
Everyone has their own ideal of HB concentration
How can we truly tell if someone was Hb deficient?
won’t make more if iron sufficient so if Hb increases must have been iron deficient
Why do we use a single cut off for iron deficiency?
Good way to assess the bulk of the population
What factors affect the validity of iron data?
- method of blood collection
- fasting status/ time of day: iron supplement before or meal iron will be transport so serum will be higher/ iron levels also decrease across the day
- Assay/ equipment used
- Infection/ inflammation
- Environment & other confounding factors (lead)
- Genetics
- Oral contraceptive agents decreases TS
- smoking increase Hb
- Altitude increase Hb
- Sports anaemia decreases Hb (because more fluid in blood)
- Dehydration make indices seem better
How does infection effect iron data?
acute phase response blocks release of Ferritin & increases translation of ferritin (more) causing it to be artificially elevated which leads to a shortage of Fe in bone marrow (Important to have a measure of infection
What are some more sources of anaemia?
Can also be cause by infection, reduced erythropoiesis (bone marrow, depression, b1, folate) & genetic disorders (thalassemia, sickle cell anaemia)
What indicies differentiate IDA, chronic disease, macrocytic anaemia & thalassemia?
- Chronic disease: ferritin & ZPP high, Hb low, rest = normal
- Macrocytic anaemia: low Hb, Hih MCV, MCH, High Ts, norm ZPP & ferritin
- Thalassemia: low Hb, MCV, MCH, high TS
- IDA: all low but ZPP
What does ADIME stand for?
Assessment, Diagnosis, Intervention, and Monitoring and Evaluating
What does NCP stand for?
Nutrition care process model
what is in the centre of the NCP model?
Individuals
What is stage 1 of the NCP?
- Nutrition assessment: systematically obtains & verified & interprets relevant info against recognised standards to identify nutrition related problems
What is done pre NCP stages?
Screening & referral
+ identify risk factors
+ use appropriate tools & methods
+ involve interdisciplinary collaboration
What is stage 2 of the NCP?
Nutrition diagnosis: identify & labels specific nutrition problem that the practitioner is responsible for sorting
What are the steps of stage 1 (assessment) of the NCP
+ collect data (what’s available; what’s missing)
+ record & verify info
+ interpret evidence based)
+ re-assessment (follow-up) addresses monitoring/ evaluating parameters
What is the purpose of stage 1 (assessment) of the NCP?
Provides the prompts & evidence for developing the nutrition diagnosis
What are the 5 types (domains of nutrition assessment)?
- Client Hx
2. Anthropometric measures
3. Biochemical data, medical tests, procedures
4. Clinical info/ nutrition focused physical findings
5. Diet-related History
What are the 4 areas of nutrition diagnosis?
+ food nutrient intake
+ clinical findings/ observation
+ behavioural/ environmental
+ other
How should a nutrition diagnosis been delivered?
Pass statements:
Problem: thinking of problem
Aetiology: why is it happening
Signs & symptoms: how do you know it’s a problem
What is stage 3 of the NCP?
nutrition intervention: formulates goal & develop plan of action in consultation with the patient + care team
What are the 4 categories of nutrient interventions?
- Food & nutrient delivery
- Nutrient education
- Nutrition counselling
- Co-ordination of nutrition care
Nutrition intervention goals must ____?
prioritise nutrition diagnosis Identify patient-focused goals determine nutrition goal Convert it into actual foods (milk instead of calcium) SMART
What data may be invasive?
Anthropometric;
use nutritional/ biochemical instead
What is stage 4 of the NCP?
Nutrition monitoring & evaluating: nutrition indicators that reflect a change as a result of nutrition care
What are 4 ways we monitor progress in stage 4 of the NCP?
+ check understands & compliance
+ Provide evidences that a plan is changing behaviour/ nutrition status
+ identify other positive/ negative evidence
+ support conclusions with evidence
What are 3 steps of stage 4 of the NCP?
monitor progress
Measure outcomes
Evaluate outcomes
How do we measure outcomes in stage 4 of the NCP?
+ select relevant indicators (what to see if intervention works)
How do we evaluate outcomes in stage 4 of the NCP?
+ compare current with previous
+ consider diagnosis & intervention plan
When obtaining client history what personal info do we need to collect?
• Contact details • GP • Age, DOB, gender, sex • Race ethnicity, language, religion • Literacy, education • Smoking, alcohol, drugs, supplements, medications • Any relevant disabilities, mobility • Explain purpose – relevance of some questions • Physical activity/training load/pinnacle event • Gut microbiome – may ask AB use, birth process • MC/OCP use
When obtaining client history what social info do we need to collect?
+ Socioeconomic factors
+ Living/ housing situation (roles & responsibilities)
+ Recent alterations to living situation
+ Occupation (PA, stress, knowledge, income)
+ Connections to social group
+ Stress & coping
When obtaining client history what medical/health history information do we need to collect?
+ previous nutrition input (from doctor, nutritionist, naturopath)
+ reasons for referral; relevant symptoms/ challenges/ info
+ personal health history
+ relationship with food/ body image (fam history
+ medical conditions that effect food choices/ intake
What are some nutrition focused physical findings in healthy clients?
- changes in appetite
- changes in body wt/body composition
- injury hx
- immunity hx
- oral health
- body language (body image)
- stools (Bristol stool chart)
- hydration status (urine colour)
- bloating/cramping (gut)
- cramping (muscle)
- satiety
- fatigue
What are some nutrition focused physical findings in clinical patients?
- muscle and subcutaneous fat
- suck/swallow/breathe ability
- altered taste
- grip strength
- BP results
- other
How do novice, beginner, competent, proficient & expert practitioners use the NCP differently?
- novice: Rule/ tool dependant (lacks context & judgement)
- Beginner (controlled learning & begins to appreciate context)
- Competent (differentiates between important/ unimportant data; selects task appropriate rules/ tools)
- Proficient (Prioritization; situational discrimination & experience based problem solving)
- Expert (inituative; sees whole situation)
The nutritioner practioner must be ___…. in order to complete a successful NCP.
- non-judgemental
- aware of how NP is percieved
- understand privlege
- thorough
- able to group relevant info
- active listener (asks open ended questions)
when should BMI not be used?
In an athlete as they have more muscle mass
what are 7 clinical active listening skills?
- ask open-ending question
- Ask probing questions
- Request clarification
- Paraphrase
- Be attuned to feelings & reflect feelings
- Summarise
Define diagnosis?
group data to triage & prioritise specific nutrition problem
Why is it important to look at context when carrying out a NCP?
Something healthy may be unhealthy in some contexts so have to have empathy
What are the 4 categories of information of interest when carrying out a Food & Nutrition Related Hx?
- NUTRIENT INTAKE
Composition & adequacy, meal & snack of patterns, previous diets, increased intake through supplementation (prescribed or not?) - Food & Nutrient Administration
current & previous diets & food modifications
Eating environments - Knowledge, beliefs & attitude
understanding of nutrition concepts, readiness to behaviour change, food & nutrient literacy - Behaviours
activities that influence the achievement of nutrition related goal
What are the 2 main types of errors in food & nutrient history?
- Recall errors (omission & commission)
2. Collector errors
what are some types of collector errors?
- Insufficent/ incomplete info gathered
- Estimated (portion size estimation)
- Subconscious & incidental eating is often forgotten
- Completed by client
- Inappropriate source used for data conformation
what info should we collect when carrying out a food & nutrient history?
- Time of intake
- Portion size
- Cooking methods
- Food type
- Brand names
- Seconds
- Fluid
- Anything else
What do incorrect estimates of portion sizes come from?
- . Inability to estimate
- Misconception of what is average
- props & tools may not represent familiar cookery
How do we minimise error when estimating portion size?
- Portion size aids
- Standardised photographs, plate drawings & food models
- Household measures
- Broader questions “how much of this do u buy a week
what are 7 meal time considerations that need to be made when carrying out a food & nutrient history?
- Shift workers
- Food intake vs hunger
- Fad diets
- Time lapse to adverse reactions
- Food not prepared cooked by client
- Ready made meal service
- Unfamiliar takeaway
what are 6 more considerations that need to be made when carrying out a food & nutrient history?
- Weekend routines
- Snacks/ grazing frequently
- “all or nothing” personalities
- Disordered eating
- Guilt associating eating
- Blended families “varitation across households”
What are common issues when carrying out a food & nutrient history?
- Not clarifying timelines
- Not considering the client journey
- Client to keen to share food intake
- Missing the unknown unknowns
- Understand the food record is not possible or sustainable
What are the main 4 things we should so when carrying out a food & nutrient history?
- Ask open ended questions
- Keep asking probing questions
- para-phrase
- recap
How do we interpret data from a a food & nutrient history?
- Compare intakes with requirements (NRV’s & evidence based practice guidelines)
e. g. plate model, MoH – age & stage recommendation , national heart foundation, diabetes, position stand, review article
How do we carry out a qualitative analysis of a food & nutrient history?
- Selecty appropriate standard
- Determine no. of servings in each food froup
- Compare with recommended no. of servings
What to consider when interpreting nutrient concerns?
- food groups deficient/ excessive
- how do these relate to the clients referral
- Omission bias
when undergoing a Food/ nutrition related history what information do we want to gather about physical activity?
- Intensity
- Duration
- Frequency
- Functional ability
- Limitations (personal safety, sun exposure, budget)
when undergoing a Food/ nutrition related history what information do we want to gather about personal circumstances?
- Food prep skills + resources
- Transportation
- Food security
- Quality of life
- Ethical decision making
when undergoing a Food/ nutrition related history what information do we want to gather about history with behaviour change?
- When did a change occur
- How long did it last
- What did they make the change
- What factors encourages success
- Inhibitors
- If no Positive stories talk about positive life changes
- Assess readiness to change
