dr helen o'connor - nutrition knowledge - does knowing about nutrition change what you eat
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Nutrition Knowledge Does Knowing About Nutrition
Change What You Eat?
Helen O’Connor PhD APD
Exercise & Sport Science
Faculty of Health Sciences
University of Sydney
Why Measure Nutrition Knowledge
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Unhealthy
Eating
Pattern
Healthy
Eating
Pattern
Nutrition
Knowledge
Taste
Food Security Beliefs
Culture & Religion
Convenience
& Availability
Kinds of Knowledge
Declarative
› Knowledge of ‘What & Why’ (FACTS)
› Boiling water burns your skin
› Butter is a fat
› Butter contains saturated fat
› Saturated fat is linked with heart disease
Procedural
› Knowledge of ‘How & Do’ (SKILL-APPLICATION)
› I can use insulated cup to hold boiling water
› How to read a food label & select appropriate option
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Increasing
Complexity
Facts & Application
Needed for Effective
Dietary Change
Knowledge versus Beliefs
The link between knowledge and perception
› ‘I think butter is better than margarine’
› Beliefs can be strong or weak
› Scientists propose new beliefs – an hypothesis
› Many food beliefs
› ‘If you do not eat the crust on bread, hair won’t be curly’
› Beliefs influenced by our experience of the world
› Marketing is highly influential
- ‘I need supplements to stay healthy or stronger’
› ‘mumfacts’ & ‘dadfacts’ highly influential
4
Knowledge versus Beliefs
› Established beliefs influence our capacity to respond to new
information
› Strong, entrenched beliefs
- Difficult to accept new information
› Weaker, flexible beliefs
- More open new information
› Beliefs influence our motivation to change behaviour
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Defining Nutrition Knowledge
› Knowledge of nutrients & nutrition
› Knowledge of nutrients in food
› Knowledge of how food & nutrients influence health
› What to consumers ‘need to know’ vs ‘nice to know’
› Currently little consensus on ‘core competency’
› Tools used to measure nutrition knowledge are varied
- Dietary guidelines & daily serves of core foods
- Nutrients in food (e.g. oranges good source of Vitamin C)
- Diet disease relationships (e.g. saturated fat & heart disease)
- Few tools assess process knowledge
- Selecting lower fat meal or reading food labels
6
How related are the
nutrition knowledge tests
to food choice?
Food Label: Consumers Vs Nutritionists
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Worsley, 1996
Measurement of Nutrition Knowledge
› Typically written questionnaire
- Not assessed for the level of literacy needed to respond
› Most Instruments have limited to no validation
- Report a score with no frame of reference
- Score then has no ‘real world’ meaning
- Ideally instrument completed by experts (e.g. Dietitians)
- Also by representative sample of the community
- Some instruments used across different cultures
- May not be culturally appropriate food choices
- No pilot test, test re-test or internal consistency validity
- Items become dated
8
Measurement of Nutrition Knowledge
What areas of nutrition does the instrument measure?
› General nutrition (diet guidelines, core food intake)
› Specific areas (e.g. knowledge of fat, fibre)
› Facts or application of knowledge
› Diet disease relationships
› Are the questions relevant to the participant?
- Diet disease relationships: less relevant to younger/athletes?
› Does the test probe knowledge, beliefs or attitudes?
› Instrument formats
- Multiple choice (skill required to do)
- Written answers – literacy an even greater issue
- Items: number and currency
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Factors Influencing Nutrition Knowledge
› Age
- Middle aged greater than younger or older
› Gender
- Women > men
- Role in food preparation greater in women
- Less interest in nutrition by men
› Level of Education and SES
- Higher in better educated
› Athletes
- Greater in higher calibre; possibly greater in physique sports
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Heaney et al 2011
Nutrition Knowledge: Australians
Aims:
Assess and benchmark general nutrition knowledge using the
validated general nutrition knowledge questionnaire (GNKQ)
› Elite Australian athletes (EA)
› Community group (CM) of similar age
› Criterion cohort with dietetic training (DT)
› Further evaluate the validity and psychometric properties of
the GNKQ
Spendlove et al 2012
Nutrition Knowledge of Australians
General Nutrition Knowledge Questionnaire (GNKQ)
- Validated in community groups UK & Australia
- Used in athlete groups UK & US
- Section A: Dietary guidelines (declarative – what)
- Section B: Sources of nutrients (declarative – what)
- Section C: Choosing everyday foods (procedural – how)
- Section D: Diet-disease relationships (declarative – why)
Demographic Characteristics
- Age, gender, level of education, ethnicity, physical activity (h)
- Athletes: – Calibre, sport (team VS individual), training time (h)
Content validity of GNKQ
› Invited panel (experienced APD & nutrition researchers; n=20)
› Purpose-developed evaluation form
- Retain, modify or delete (detailed comments)
- Item removal: ambiguous/inaccurate & > 50% DT incorrect
Revised – GNKQ (R-GNKQ)
› GNKQ 113 item 96 items (items removed across all sections)
› Revised scoring (Section D : Diet-Disease Relationships)
Nutrition Knowledge of Australians
Excluded Question GNKQ
Question 8 (Section C)
Which of these would be the healthiest dessert?
(a) baked apple
(b) strawberry yoghurt
(c) wholemeal crackers and cheese
(d) carrot cake with cream cheese topping
Based on:
Nutrition benefit?
Calcium content?
Lowest kilojoules?
Higher in fibre?
How was the
apple baked? Low fat yoghurt?
How much cheese ?
Reduced fat?
Nutrition Knowledge of Australians
Total
(n=344)
Athletes (n=175)
State Sports
Institute (n=157)
Surf Lifesaving
& NRL (n=18)
Community (n=116)
Scouts 18 – 26y (n=39)
Arts Students
(n=77)
Dietetic Criterion Cohort (n=53)
Dietetic Interns (n=33)
APD (n=20)
Spendlove et al 2011
Characteristics Athlete
(EA)
Community (CM)
Criterion
(DT)
Comparison between EA& CM group means
p-value
Age
mean
≤ 18 y
19 – 24 y
≥ 25 y
18.9 ± 4.9
117 (66.9%)
46 (26.3%)
12 (6.9%)
21.9 ± 4.2
8 (6.9%)
93 (80.2%)
15 (12.9%)
29.1 ± 8.5
0 (0%)
21 (39.9%)
32 (60.1%)
<0.001
Gender
Male
Female
76 (43.4%)
99 (56.6%)
32 (27.5%)
84 (72.5%)
7 (13.2%)
46 (86.8%)
<0.007
Level of Education
High School
Tertiary
116 (66.3%)
59 (33.7%)
9 (7.8%)
107 (92.2%)
0 (0%)
53 (100%)
<0.001
Total Sample (n=344) n%
Nutrition Knowledge of Australians
40
45
50
55
60
65
70
75
80
85
90
95
100
Total Section A Section B Section C Section D
EA
CM
DT
Nutrition Knowledge Scores GNKQ
K
n
o
w
l
e
d
g
e
S
c
o
r
e
%
* *
#
#
#
#
#
# p<0.001
*p<0.001
Dietary
guidelines
Sources of
nutrients
Choosing
everyday
foods
Diet-disease
relationships
Hendrie et al sample 2008
Main Differences in R-GNKQ
40
45
50
55
60
65
70
75
80
85
90
95
100
Total Section A Section B Section C Section D
EA
CM
DT
#
#
# # #
* *
*
*
K
n
o
w
l
e
d
g
e
s
c
o
r
e
%
Dietary
guidelines
Sources of
nutrients
Choosing
everyday
foods
Diet-disease
relationship # p<0.001
* p<0.007
Does Nutrition Knowledge Influence Intake?
Yes a little BUT
Good evidence is scarce
› Poor conceptualisation of nutrition knowledge
- Lack of relevance
- Knowledge of cholesterol less relevant to teens
› Poor measurement
- Non validated, culturally inappropriate tools often used
› Lack of specificity
- e.g. general knowledge test used for diet fat intake
› Small samples (under powered)
- Not representative; female dominated; tertiary educated
19
Nutrition Knowledge Vs Health Literacy
› The American Dietetic Association recognises health literacy as one of seven key public healthy priority areas.
› Described this as a ‘mega issue’ for the profession of dietetics
› Health literacy on US health care agenda for over a decade
› Definitions vary but generally defined as
‘the capacity of individuals to obtain, process and understand basic health information and services needed to make appropriate health decisions’.
› Health literacy includes print, media and numeracy literacy and cultural, conceptual knowledge.
› Nutrition knowledge is a component of this broader more complex concept of health literacy.
› Only 12% of US adults are considered to have adequate health literacy.
20
Nutrition Knowledge Vs Health Literacy
Low health literacy has been associated with
increased disease risk
› Lifestyle disease including obesity, type II diabetes, cancer.
› Recently also linked to low Healthy Eating Index Scores in US
population
Low health literacy makes it difficult to:
› Read and understand a food label; dose medication
› Acquire and understand new health information
- e.g. dietary guidelines
- Understand risk such as how lifestyle choices influence health
21
Nutrition Knowledge Vs Health Literacy
› None of the tools which assess nutrition knowledge are
assessed for print or numeracy literacy level required to
understand the questions
› New nutrition knowledge assessment tools are required
- Lower literacy friendly instruments
- Technology can be used more graphics
- Audio files
› Assessment of health literacy should accompany
measurement of nutrition knowledge.
22
Does Knowing About Nutrition Change What You Eat?
› Scientific evidence is poor quality
› Likely a weak positive effect
› Nutrition knowledge is still likely pivotal
› One must know before one can do
› BUT relationships are complex; one can know and not do!
› Knowing about nutrition requires adequate literacy (print & numeracy)
› Nutrition knowledge assessment tools must consider literacy
› Education materials must consider literacy
› Literacy is likely lower than anticipated
› Better understanding nutrition knowledge & health literacy will guide:
- Nutrition education programs
- Dietetic counselling
- More effective research in this domain
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