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

2

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

3

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

5

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

7

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

9

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.

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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

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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.

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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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