Literature review of Vegetable Consumption

Fruit and vegetable consumption among young adults

The World Health Organisation is predicting that chronic disease will account for over sixty per cent of deaths; with 41 million deaths by 2015.1 Up to 80% chronic disease could be prevented by eliminating tobacco use, unhealthy diet, physical inactivity and the harmful use of alcohol.2 Chronic disease and obesity in Australia are continuing to contribute to premature death and burden of disease.3 Cardiovascular disease and cancer remain the main causes of disease burden and type 2 diabetes prevalence has trebled in the last ten years and is expected to be the leading cause of disability and death by 2023.4 The rapid rise in diabetes incidence and prevalence is thought to be due to the rising rate of obesity.5 61% of Australian adults, using measured BMI are currently either overweight or obese6 , with younger age groups gaining weight more quickly than previous generations.7 Approximately 32% of Australia’s total burden of disease can be attributed to modifiable risk factors.4

Considerable reductions in morbidity and mortality from diet-related diseases could be achieved if the population increases healthy eating behaviours including increasing the consumption of fruit and vegetables (FV).8 Fruit and vegetable consumption is strongly linked to the prevention of chronic disease and to achieving better overall health.9 Internationally up to 2.6 million deaths and 1.8 % of global burden of disease is attributable to low FV consumption. Inadequate FV intake in Australia is thought to be responsible for 2.1% of the overall burden of disease.10 Increasing individual FV intake could reduce the burden of cardiovascular disease by 31%.11 In particular reviews of studies have indicated that FVs reduce the risk of developing cancer12; cardiovascular disease13 and obesity.14,15 A meta-analysis of studies investigating FV intake and the incidence of type 2 diabetes indicated no significant benefits for increasing FVs but an increase in green leafy vegetables could significantly reduce the risk of Type 2 diabetes.16 The mechanism of action is thought to be related to their micronutrient, antioxidant, phytochemical and fibre content.17

Current recommendations for fruit and vegetable consumption
Based on available evidence the World Cancer Research Fund recommends eating at least 400g of non-starchy vegetables and fruits per day (2007).12 The Australian Dietary Guidelines recommend that Australians consume a minimum of two serves of fruit and five serves of vegetable daily.9 Current consumption patterns are well below these figures. Data on FV consumption in Australia is collected predominantly via validated short questions as part of the National Health Survey. This self reporting of FV consumption does incorporate a number of errors related to the ability of individuals to determine serve sizes18 and the validity and reliability of the short questions. Alternative measures of FVs, predominantly food frequency questionnaires have been determined for different age groups19, 20. For adults the most recent determination of FV intake indicates that only 56% of females and 46% of males over the age of 15 are eating the recommended serves of fruit and 10% of females and 7% of males over the age of 15, are eating the recommended serves of vegetable daily.15 The 2007 national children’s nutrition and physical activity survey used a combination of multipass 24 hour food recalls and food frequency and indicated that only 1-2% of older children were consuming three serves of fruit and only 1-11% of older children met the guideline for vegetable consumption21. In another survey specifically looking at young adults 34-43% of those aged 19-24 year olds met the daily fruit consumption guidelines of two serves a day but only 8-10% of young adults ate the recommended five serves per day of vegetable.3, 22 Low consumption of FVs is, therefore, an issue across the spectrum of age groups. While young adults do not necessarily have FV intakes any worse than older adults and children, the lack of overt medical problems has meant that the 18-24 year old age group have received little attention.23 Given that fewer young adults consume the recommended serves of vegetable, strategies that focus solely on vegetables would appear to be appropriate.

Young adulthood is a critical age for weight gain24; and in the United States the transition from high school to college is a potential period of rapid weight gain increasing the risk of obesity in later adulthood.25 Chronic conditions are a significant challenge for Australia’s young people because these conditions can affect normal growth and development, quality of life, long-term health and wellbeing, and successful participation in society, education and employment.3

Studies predominantly undertaken in the United States and Europe are contradictory with respect to whether food habits are positively or negatively affected in the transition to independence. In one study students living independently were more likely to consume a healthy diet than their counterparts living at home. Independent living may increase responsibility of various food-related activities such as budgeting, purchase, preparation and cooking which young adults living at home have not yet developed.26 Other research however indicates that dependent students consume more FVs – independent students may take more responsibility for their food choices while dependent students may be controlled by the primary care-givers.27 It should be noted that the transition from highschool to university in Australia is not necessarily marked by a move out of the family home as it does in the United States, Canada and parts of Europe. Living on campus or in university-provided accommodation is only undertaken by a small percentage of students in Australia.

In 2008, there were almost 3 million young people aged 15–24 years in Australia, accounting for 14% of the total population.3 In addition the majority of Australians who start a course at a higher education institution are aged between 15 and 34 years of age and in 2009 more than 45% of young adults aged 18-24 years were enrolled in a course of study leading to a degree or diploma qualification.28 Universities and other higher education institutions would therefore be an appropriate setting to target individuals in this age group.

Determinants of fruit and vegetable consumption
The National Public Health Partnership identified the primary determinants of FV consumption to inform the development of strategies.29, 30 These are outlined in the table below.

Table 1 Identification of determinants of fruit and vegetable consumption
Determinant
Objectives
Food supply
Increase and sustain access to high quality, safe, affordable FVs
Awareness
Increase the proportion of the population aware of the need to increase consumption of FVs
Attitude/Perceptions
Increase the proportion of the population who perceive the benefits of FVs in terms of taste, convenience, low relative cost, safety and health.
Knowledge
Increase the proportion of the population with the knowledge of the recommended minimum intakes of FVs
Skills to purchase and prepare
Increase the proportion of the population with the knowledge, skills and confidence to select and prepare convenient low cost, tasty FV dishes For children, adolescents and adults, previous consumption or exposure to FVs, knowledge, awareness, preparation skills and involvement in food preparation, lack of time and taste preference have all been implicated in the consumption of FVs .31,32,33 From an environmental perspective, availability of FVs within home, school and community settings plays a significant role in promoting FV consumption.32, 34 Those who report eating home grown produce have significantly higher intakes of FVs while poor accessibility to shops and high FV prices have been shown to have a negative impact on FV consumption.35, 36

The presence of a major food retailer in an area has been associated with improved FV consumption.37 In Australia, the evidence is less clear-cut with those living in socioeconomically disadvantaged areas having similar opportunities to purchase FVs when compared to those in levels of higher advantage.38 Recent work has indicated that price and availability in disadvantaged areas are similar to those in more advantaged areas but that quality could be seriously compromised, which could impact purchasing behaviour.39 FV prices have been identified as a significant barrier in FV consumption with intakes among those of lower and middle socioeconomic positions more price responsive than their higher socioeconomic position counterparts (Powell et al 2009).40 The national public health partnership identified the lack of recognition of the low relative cost of FVs as a barrier to consumption.29 However, given the recent rapid increase in FV prices identified by the Australian Bureau of Statistics (15.5% increase for fruit and 11.4% increase for vegetables in the December 2010 quarter) the perception of cost now may be a reality and a significant barrier to consumption.41

For young adults at university many of the determinants described above are applicable. In addition, access to cooking facilities and equipment, increased availability of unhealthy and convenience foods choices, lack of access to transport, cost of food, lack of time to prepare and to shop, lack of knowledge and of cooking skills were all identified as barriers to FV consumption.42, 43 Given the increased mobility of young adults a focus on home or school may not be sufficient. Recent research indicates that 40% of eating occasions for young adults were on average 6.7 miles (10.5 km) away from their primary place of residence regardless of whether they were living with care-givers or independently.44 This being the case proximity may play a relatively minor role in an individual’s food choices. Instead decisions may be based on a complex web including food quality, pricing, variety, availability, travel patterns, social or cultural influences and various other factors.44

Strategies
Based on the determinants and using the Ottawa Charter as a framework, strategies can be divided into two primary categories those that build personal skills and those that create supportive environments. The majority of interventions have not been undertaken with the target group but rather with children (primarily in school settings) and adults. Work with the young adult age group however has highlighted that there is a general lack of understanding about motivators25 but that negative health outcomes are not particularly relevant and the focus should be more on taste.45 Social and environmental cues, on the other hand, could be especially significant.46

In Australia, the broadest population campaign has been Go for 2 and 5. This media campaign began in Western Australia and has since been implemented nationally and in each individual state. The campaign primarily aimed to increase FV consumption through the increased awareness and knowledge of the benefits of FVs, ways to cook FVs and serve size awareness. Evaluation has indicated that the campaign was successful in reaching the target audience and achieving increased awareness of recommended serves of FVs. The Western Australian campaign achieved an average increase of 0.5 of a serve.28 Primary target groups have been children and adults, adolescents and young adults have not been a focus. Education strategies have included embedding curricula in primary and secondary schools and providing regular newsletters to increase knowledge.47 For children and adolescents other successful strategies focus on creating supportive environments combined with elements of education including the provision of free or subsidised fruit either directly or through the provision of tasting programs, snacks, gardening or cooking.47,48, 49, 50 Within more community settings, interventions have included point of purchase information, reduced pricing, promotion and advertising and increased availability and variety.51 However, there is little evaluation of the effectiveness of these strategies for improving fruit and vegetable consumption in the wider community. Very few of these interventions have been trialled with young adults as the target group. For the few programs that have focussed on young adults the strategies have centred on the development of personal skills through the provision of education either as on-line individualised programs25; tailored individualised counselling52; newsletters promoting FV intake23; and via a general nutrition course to enable students to move from knowledge to application.53 All of these showed modest short term increases in FV intake, a lack of data means that long term establishment of behaviour has not been determined.

Based on the available evidence there is a need to focus on increasing fruit and vegetable consumption among young adults. Given the large numbers of young adults at tertiary institutions – universities are an appropriate setting. There are few strategies that particularly focus on young adults in the Australian context. However, based on the underlying determinants, strategies should focus on improving knowledge, awareness and preparation skills, changing taste preferences, increasing availability of FVs within local settings, reducing the cost of FVs in selected settings. The development of a comprehensive, multi-strategy program specifically addressing increased fruit and vegetable consumption is required in order to improve general health outcomes and specifically reduce the risk of chronic disease.

References
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