Nutrition knowledge and food consumption: can nutrition knowledge change food behaviour?

The status and explanatory role of nutrition knowledge is uncertain in public health nutrition. Much of the uncertainty about this area has been generated by conceptual confusion about the nature of knowledge and behaviours, and, nutrition knowledge and food behaviours in particular. So the paper  describes several key concepts in some detail. The main argument is that 'nutrition knowledge' is a necessary but not sufficient factor for changes in consumers' food behaviours. Several classes of food behaviours and their causation are discussed. They are influenced by a number of environmental and intra-individual factors, including motivations. The interplay between motivational factors and information processing is important for nutrition promoters as is the distinction between declarative and procedural  knowledge. Consideration of the domains of nutrition knowledge shows that their utility is likely to be related to consumers' and nutritionists' particular goals and viewpoints. A brief survey of the recent literature shows that the evidence for the influence of nutrition knowledge on food behaviours is mixed. Nevertheless, recent work suggests that nutrition knowledge may play a small but pivotal role in the adoption of healthier food habits. The implications of this overview for public health nutrition are: (i) We need to pay greater attention to the development of children's and adults' knowledge frameworks (schema building); (ii) There is a need for a renewed proactive role for the education sector; (iii) We need to take account of consumers' personal food goals and their acquisition of procedural knowledge which will enable them to attain their goals; (iv) Finally, much more research into the ways people learn and use food-related knowledge is required in the form of experimental interventions and longitudinal studies.

Income differences in food consumption in the 1995 Australian national nutrition survey

Objective: To assess the relationships between an index of per capita income and the intake of a variety of individual foods as well as groups of food for men and women in different age groups. Design: Cross-sectional national survey of free-living men and women. Subjects: A sample of 5053 males and 5701 females aged 18 y and over who completed the Australian National Nutrition Survey 1995. Methods: Information about the frequency of consumption of 88 food items was obtained. On the basis of scores on the Food Frequency Questionnaire, regular and irregular consumers of single foods were identified. The relationships between regularity of consumption of individual foods and per capita income were analysed via contingency tables. Food variety scores were derived by assigning individual foods to conventional food group taxonomies, and then summing up the dichotomised intake scores for individual foods within each food group. Two-way ANOVA (income age group) were performed on the food variety scores for males and females, respectively. Results: Per capita income was extensively related to the reported consumption of individual foods and to total and food group variety indices. Generally, both men and women in low income households had less varied diets than those in higher-income households. However, several traditional foods were consumed less often by young high-income respondents, especially young women. Conclusions: Major income differentials in food variety occur in Australia but they are moderated by age and gender. Younger high-income women, in particular, appear to have rejected a number of traditional foods, possibly on the basis of health beliefs. The findings also suggest that data aggregation has marked effects on income and food consumption relationships.

The relationship between education and food consumption in the 1995 Australian national nutrition survey

Objective: To assess the relationship between education and the intake of a variety of individual foods, as well as groups of foods, for Australian men and women in different age groups.

Design: Cross-sectional national survey of free-living men and women. Subjects: A sample of 2501 men and 2739 women aged 18 years and over who completed the National Nutrition Survey (NNS) 1995.

Methods: Information about the frequency of consumption of 88 food items was obtained using a food-frequency questionnaire in a nation-wide nutrition survey. Irregular and regular consumers of foods were identified according to whether they consumed individual foods less than or more than once per month. The relationship between single foods and an index of education (no post-school qualifications, vocational, university) was analysed via contingency table chi-square statistics for men and women. Food group variety scores were derived by assigning individual foods to conventional food group taxonomies, and then summing the dichotomised intake scores for individual foods within each food group. Two-way analyses of variance (education by age groups) were performed on food variety scores for men and women, separately.

Results: While university-educated men and women consumed many individual foods more regularly than less-educated people, they were less likely to be regular consumers of several meat products. The relationship between education and food consumption was less apparent when individual food scores were aggregated into food group scores. University-educated men and women exhibited higher scores on total food group variety than the other educational groups.

Conclusions: Higher education is associated with the regular consumption of a wider variety of foods. Aggregation of individual food consumption indices into food variety scores may mask the apparent effects of educational background on food consumption.

The influence of perceived body image, vanity and personal values on food consumption and related behaviour

Although food is a vital part of the chemical process of life, the manner in which people choose the foods that they eat is subject to a wide variety of external and internal influences. This study employed a sequential mixed method research design to investigate the influence of perceived body image, vanity and personal values on food purchasing behaviour among 18- to 30-year-old females. It was found that although personal values and orientation have a major influence on the food purchasing and consumption process, vanity, physical health and perceived body image were major factors of influence in the purchasing and consumption decision.

Hierarchical relationship between values, lifestyles, possessions and food consumption among Beijing adult population

A representative sample (N=801) of the Beijing adult population was used to empirically test and validate a proposed hierarchical model of relationships between values, lifestyles, possessions and food consumption. The theoretical contribution of the present study is the development and an empirically supported paradigm, which explains consumers' consumption behaviour. A further outcome is the substantiation of a pathway model involving hierarchical relationship between values, lifestyle, and demographic variables on material possessions and food consumption.

Takeaway food consumption, diet quality and abdominal obesity in young adults

Background - Takeaway food consumption is associated with a higher BMI and poorer diet quality in the USA but little is known about the association in Australians.
Objective - To examine if takeaway food consumption is associated with abdominal obesity and poorer diet quality in young Australian adults.
Design - A national sample of 1,277 men and 1,585 women aged 26-36 completed a self-administered questionnaire on demographic and lifestyle factors, a 127 item food frequency questionnaire, and usual frequency of fruit, vegetable and takeaway food consumption. Dietary intake was compared with the dietary recommendations of the Australian Guide to Healthy Eating. A pedometer was worn for seven days. Waist circumference was measured and moderate abdominal obesity was defined as ≥94 cm for men and ≥80 cm for women. Prevalence ratios (PR) were calculated using log binomial regression with eating takeaway food once a week or less as the reference group.
Outcomes - Consumption of takeaway food twice a week or more was reported by more men (37.9%) than women (17.7%). Participants eating takeaway food at least twice a week were less likely to meet the guidelines for vegetables (P<0.05 men and women), fruit (P<0.001 men and women), dairy (P<0.01 men and women), extra foods (P=0.001 men and women), breads and cereals (P<0.05 men only), lean meats and alternatives (P<0.05 women only) and overall met significantly fewer dietary guidelines (P<0.001 men and women) than participants eating takeaway less than twice per week. After adjusting for confounding variables (age, physical activity, TV viewing, and employment status) consuming takeaway food twice a week or more was associated with a 31% higher prevalence of moderate abdominal obesity in men (PR 1.31; 95% CI: 1.07, 1.61) and a 25% higher prevalence in women (PR 1.25; 95% CI: 1.04, 1.50).
Conclusion - Eating takeaway food twice a week or more was associated with poorer diet quality and a higher prevalence of moderate abdominal obesity in both young men and young women.

Takeaway food consumption and its associations with diet quality and abdominal obesity : a cross-sectional study of young adults

Background : Few studies have investigated the associations of takeaway food consumption with overall diet quality and abdominal obesity. Young adults are high consumers of takeaway food so we aimed to examine these associations in a national study of young Australian adults.

Methods : A national sample of 1,277 men and 1,585 women aged 26–36 completed a self-administered questionnaire on demographic and lifestyle factors, a 127 item food frequency questionnaire, usual daily frequency of fruit and vegetable consumption and usual weekly frequency of takeaway food consumption. Dietary intake was compared with the dietary recommendations from the Australian Guide to Healthy Eating. Waist circumference was measured for 1,065 men and 1,129 women. Moderate abdominal obesity was defined as ≥ 94 cm for men and ≥ 80 cm for women. Prevalence ratios (PR) were calculated using log binomial regression. Takeaway food consumption was dichotomised, with once a week or less as the reference group.

Results : Consumption of takeaway food twice a week or more was reported by more men (37.9%) than women (17.7%, P < 0.001). Compared with those eating takeaway once a week or less, men eating takeaway twice a week or more were significantly more likely to be single, younger, current smokers and spend more time watching TV and sitting, whereas women were more likely to be in the workforce and spend more time watching TV and sitting. Participants eating takeaway food at least twice a week were less likely (P < 0.05) to meet the dietary recommendation for vegetables, fruit, dairy, extra foods, breads and cereals (men only), lean meat and alternatives (women only) and overall met significantly fewer dietary recommendations (P < 0.001). After adjusting for confounding variables (age, leisure time physical activity, TV viewing and employment status), consuming takeaway food twice a week or more was associated with a 31% higher prevalence of moderate abdominal obesity in men (PR: 1.31; 95% CI: 1.07, 1.61) and a 25% higher prevalence in women (PR: 1.25; 95% CI: 1.04, 1.50).

Conclusion : Eating takeaway food twice a week or more was associated with poorer diet quality and a higher prevalence of moderate abdominal obesity in young men and women.

Social ideological influences on food consumption and BMI

Social ideologies appeared to influence dietary behaviour, physical activity and BMI. These influences varied through different pathways in younger and older baby boomers. Studies provide insight into the segmentation of baby boomer population in relation to concrete social ideologies that could be used for policy development and effective health promotion.

Oral sensitivity to fatty acids, food consumption and BMI in human subjects

Fatty acids are the chemical moieties that are thought to stimulate oral nutrient sensors, which detect the fat content of foods. In animals, oral hypersensitivity to fatty acids is associated with decreased fat intake and body weight. The aims of the present study were to investigate oral fatty acid sensitivity, food selection and BMI in human subjects. The study included two parts; study 1 established in thirty-one subjects (29 (sem 1·4) years, 22·8 (sem 0·5) kg/m²) taste thresholds using 3-AFC (3-Alternate Forced Choice Methodology) for oleic, linoleic and lauric acids, and quantified oral lipase activity. During study 2, fifty-four subjects (20 (sem 0·3) years, 21·5 (sem 0·4) kg/m2) were screened for oral fatty acid sensitivity using oleic acid (1·4 mm), and they were defined as hypo- or hypersensitive via triplicate triangle tests. Habitual energy and macronutrient intakes were quantified from 2 d diet records, and BMI was calculated from height and weight. Subjects also completed a fat ranking task using custard containing varying amounts (0, 2, 6 and 10 %) of fat. Study 1 reported median lipase activity as 2 μmol fatty acids/min per l, and detection thresholds for oleic, linoleic and lauric acids were 2·2 (sem 0·1), 1·5 (sem 0·1) and 2·6 (sem 0·3) mm. Study 2 identified twelve hypersensitive subjects, and hypersensitivity was associated with lower energy and fat intakes, lower BMI (P < 0·05) and an increased ability to rank custards based on fat content (P < 0·05). Sensitivity to oleic acid was correlated to performance in the fat ranking task (r 0·4, P < 0·05). These data suggest that oral fatty acid hypersensitivity is associated with lower energy and fat intakes and BMI, and it may serve as a factor that influences fat consumption in human subjects.

Social ideological influences on reported food consumption and BMI

Background : The purpose of this study was to investigate relationships between ideological beliefs, perceptions of the importance of health behaviours, health attitudes, food consumption, and Body Mass Index (BMI). A behavioural model was hypothesized based on the Theory of Reasoned Action (Fishbein & Ajzen, 1975).

Methods : A survey was conducted among shoppers aged between 40 and 70 years at Eastland Shopping Centre, Melbourne, Australia. The hypothesized model was tested with this empirical data (n = 410) for younger (n = 151) and older (n = 259) age groups using structural equation modelling.

Results : The findings generally support the study hypotheses. For both groups, egalitarianism had a direct and positive influence on perceptions of the importance of health behaviours. Materialism and masculinity impacted negatively on health attitudes, which positively influenced importance of health behaviours. Perceptions of importance of health behaviours impacted positively on the consumption of healthy foods such as vegetables and fruits, but negatively on consumption of unhealthy foods including sweets and fats. However, BMI was significantly influenced by the consumption of unhealthy foods (e.g., sugar and fats) only for the younger age group. Hence, the associations between beliefs, attitudes, consumption behaviours, and BMI outcomes differed between younger and older age populations.

Conclusion : Social ideological beliefs appear to influence health attitudes and thereafter, the consumption of healthy and unhealthy foods and BMI via different pathways.

Social ideological influences on food consumption, physical activity and BMI

We investigated relationships between ideological beliefs (i.e., diaphanous body image and environmental concerns), food attitudes, evening meal patterns, physical activity, and Body Mass Index (BMI). A behavioural model was hypothesized based on the Theory of Reasoned Action. A survey was conducted among shoppers aged 40–70 years at Eastland Shopping Centre, Melbourne, Australia. The hypothesized model was tested among female baby boomers (n = 547) for younger (n = 245) and older (n = 302) age groups using structural equation modeling. Findings showed that diaphanous body image had a direct and positive influence on negative food attitudes, which is likely to lead to higher BMI for both age groups. Body image beliefs were positively related to physical activity only for women aged 56–70 years. In contrast, among women aged 40–55 years, strong pro-environmental concerns suggested less consumption of both healthy (e.g., fruit and vegetables) and unhealthy (e.g., sugar and fats) foods. Moreover, strong pro-animal concerns resulted in higher BMI for the younger women. As expected, increased physical activity negatively influenced BMI. Importantly, the associations between ideological beliefs, attitudes, evening meal patterns, and BMI differed between younger and older female baby boomers.

Psychographic segmentation of Beijing adult population and food consumption

Responses from a large (801) random sample of Beijing’s adult population were used to carry out this "values and lifestyles" segmentation process and it measured consumers’ "values" and "lifestyles" directly. The results indicate that "values and lifestyle" segmentation provides marketers with a more comprehensive understanding of the consumers than by demographics alone. This study also demonstrates that marketers should not carry out segmentation automatically. They need to determine where consumers perceive a particular category of product on the "luxury" and "non-luxury" continuum before deciding whether to carry out the segmentation process or not.

Accounting for the multidimensional nature of the relationship between adult obesity and socio-economic status : the French second National Individual Survey on Food Consumption (INCA 2) dietary survey (2006–07)

The objective was to study the multidimensional nature of the relationship between adult obesity (OB) and socio-economic status (SES),
using comprehensive indices of SES taken separately or synthesised in an overall index. A nationally representative sample of adults aged
18–79 years was taken from the French second National Individual Survey on Food Consumption (INCA 2) dietary survey (2006–07).
Weight and height were measured and OB defined as BMI $ 30 kg/m². SES variables were reported in questionnaires and included
occupation, education and characteristics of household wealth. Composite indices of SES (household wealth and overall SES indices)
were computed by correspondence analysis, and relationships with OB were investigated with logistic regression analysis. In total, 11·8
(95% CI 10·1, 13·4) % of French adults were obese, without significant difference by sex. While no significant relationship was observed
in men, all SES indicators were inversely correlated to OB in women. Both education and the household wealth index were retained in the
stepwise multivariate model, confirming that different socio-economic variables are not necessarily proxies of each other regarding the OB
issue. On the other hand, ‘controlling for SES’ while including several measures of SES in multivariate models may lead to collinearity, and
thus over-adjustment. A more integrative approach may be to derive a synthetic index by including the SES factors available in a given
study. Beyond this methodological perspective, understanding how OB is related to the different dimensions of SES should help to
target the more vulnerable groups and increase the effectiveness of prevention.