Alimentación animal

The relationship between fruit and vegetable intake and chronic disease has been well documented (Miller et al., 2017, Wang et al., 2014). Links have been commonly reported with cardiovascular diseases, various cancers and obesity (Farvid et al., 2018, Russo et al., 2018, Yu et al., 2018, Zhan et al., 2017).

Examples of evidence supporting these links will now be presented.

1.6.1 Cardiovascular diseases 1.6.1.1 Coronary heart disease

The protective effect of fruits and vegetables on coronary heart disease has been reported in a number of epidemiological studies (Nikolic et al., 2008, Yu et al., 2014). A recent review observed non-linear associations for both fruits and vegetables, with optimal reductions in risk seen at the lower levels of intake.

There was a 21% reduction in relative risk up to 750 – 800 g per day for fruits and a 30% reduction in relative risk up to 550 – 600 g per day for vegetables (Aune et al., 2017). Although the amounts required to initiate positive effects remain ambiguous, a meta-analysis of 13 cohorts involving approximately 270,000 participants found that individuals consuming five or more serves per day compared to those consuming less than three serves per day had an increased reduction of 17% more in disease risk (He et al., 2006).

Similarly, another review including 469,551 participants reported average reductions in coronary heart disease mortality of 4% for fruits and vegetables combined, 4% for vegetables alone and 5% fruits alone (Wang et al., 2014). On a global scale, heart disease is said to be responsible for 7.6 million deaths worldwide, of which 1.8 million are due to low fruit and vegetable consumption (World Health Organization, 2013). It has also been reported that increasing fruit and vegetable consumption by one daily serve would reduce the risk of coronary heart disease by an average of 10% (Lock et al., 2005). A more recent Cochrane review concluded that although evidence suggests that an increase in fruit and vegetable consumption would have beneficial effects, studies were mixed with some advising consumption of at least five per day, whereas other suggested that this should be at least eight or nine portions (Hartley et al., 2013).

12 1.6.1.2 Stroke

A diet rich in fruits and vegetables is believed to have a protective effect against incidence of stroke (He et al., 2006). A meta-analyses of pooled prospective cohort studies involving over 760,000 participants showed that the risk of stroke decreased by 32% and 11% for every 200 g per day increment in fruits and vegetables respectively (Hu et al., 2014). Furthermore, an earlier review analysing nine cohorts of over 255,000 participants showed that those participants who were consuming three to five servings of fruits and vegetables per day and those consuming more than five servings per day (compared to those having less than three a day) had a relative risk of stroke of 0.89 and 0.74 respectively (Hu et al., 2014). According to the WHO, increasing an individual’s fruit and vegetable consumption to more than 600 g per day could potentially reduce the incidence of ischemic stroke by 19% worldwide and on a European scale between 10 – 15% (World Health Organization, 2004).

1.6.2 Cancer

There is an abundance of evidence available which investigates the link between fruit and vegetable consumption and cancer (Farvid et al., 2018, Löf et al., 2011, Oyebode et al., 2014, Wang et al., 2014). However, establishing the impact of effectiveness can prove difficult, primarily due to confounding factors such as alcohol, smoking and other dietary factors (Aune et al., 2017, Key, 2011). In addition to this, many studies have been proven to be methodologically flawed with exaggerated outcomes (Leenders et al., 2015). A report produced by the World Cancer Research Fund (WCRF) in collaboration with the American Institute originally published in 1997 and updated in 2007 ‘Food, Nutrition and the Prevention of Cancer: a global perspective’ has been widely drawn upon (World Cancer Research Fund, 2007). The report reviews evidence in relation to fruit and vegetable consumption and the effect on various cancers in a systematic and transparent way. This was performed in discussion with experts in the field, classifying research into categories such as ‘convincing’ and ‘limited’ based upon factors such as methodological quality and sample size. Strength of associations were based upon meta-analyses and cancers such as oesophagus, lung, stomach and mouth were deemed to be ‘probable’, whereas associations for colorectal, liver and pancreas were highlighted as being ‘limited – suggestive’

(World Cancer Research Fund, 2007). The cost of fruit and vegetable attributable

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cancers is estimated to be 42 million worldwide (World Health Organization, 2013).

1.6.3 Weight management and obesity

There is little substantive evidence which supports a direct relationship between weight and fruit and vegetable consumption. The majority of studies report on fruit and vegetables as a secondary effect in studies whose primary outcome relates to other chronic diseases (some of which have already been discussed) such as heart disease and cancer. However there are a number of studies that document an inverse relationship between fruit and vegetable intake and weight management (Bertoia et al., 2015, Heo et al., 2011, Schwingshackl et al., 2015).

A review of 17 cohort studies including over 563,000 adults concluded that a higher consumption of fruits was associated with reduction in waist circumference of -0.04 cm/year (Schwingshackl et al., 2015). Conversely, other reviews have found no or very little association between intake and weight and summarise evidence as being poor due to small sample size amongst studies as well as being methodologically weak which make inferences difficult to make (Ledoux et al., 2011, Mytton et al., 2014). Associations are often thought to be unclear, and it has been stated that diet alone cannot be held entirely responsible for weight loss (Kaiser et al., 2014). An increase in fruit and vegetable consumption, coupled with a reduction in overall energy intake and an increase in physical activity has been shown to provide the largest reduction in weight (Champagne et al., 2011).

1.6.4 Childhood obesity

Globally it has been estimated that in excess of 41 million children under the age of five years are either overweight or obese (World Health Organization, 2017).

However, there is evidence which indicates that a plateau effect is emerging in some high income countries yet this has risen in the east, south and Southeast Asia (Abarca-Gómez et al., 2017). Although this evidence is seemingly promising there appears to be no indication of a reversal effect with regard to the obesity epidemic and levels remain high enough to pose significant threats on population health (Abarca-Gómez et al., 2017, Lobstein et al., 2015, Wabitsch et al., 2014).

In the UK, approximately a quarter of reception aged children (4-5 years) are overweight on school entry, with this percentage having risen from 9.3% in 2015/16 to 9.6% in 2016/17 (Public Health England, 2018b). Furthermore

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longitudinal evidence from the UK suggests that children are now three times more likely to become overweight than forty years ago and are highly likely to become overweight or obese adults (Johnson et al., 2015b).

As with adults, holistic approaches to weight loss are also seen to be successful in the treatment of childhood overweight and obesity (Mead et al., 2017).

However, in younger age groups evidence is minimal with a recent systematic review including only 7 studies, from which no firm conclusions could be drawn due to poor quality of the research (Colquitt et al., 2016).

1.7 Why young children are an important target for promoting fruit and