Why “eat 1 more” boosts fruit and vegetable intake more than “5 a day”

A new study shows that simply telling people to “Eat 1 more” fruit or vegetable can be more effective than traditional 5-a-day messaging—if the goal feels achievable, it works.

 Study: ‘Eat five a day’ vs ‘eat one more’: increased fruit and vegetable consumption when goals are provided, and when goals are more achievable or perceived to be easier. Image Credit: Focus and Blur / Shutterstock

In a recent study in the journal Appetite, researchers synthesized the findings from three independent studies to evaluate the potential benefits of setting consumption goals in meeting fruit and vegetable (FV) consumption targets. The studies explicitly investigated the “relevant” and “achievable” elements of these goals.

Study findings revealed that FV consumption increases significantly in the presence of a predefined goal compared with no set goals. In some cases, participants’ perception of ease or achievability of the goal further promoted FV consumption. In contrast, the relevance of the FV goal did not appreciably alter FV consumption. However, it is important to note that the increases observed were statistically significant but modest in size.

Background

Fresh fruits and vegetables (FVs) are among the most healthy and cost-effective sources of essential nutrients for humans, with their routine consumption scientifically validated to substantially reduce the risks of major chronic diseases (e.g., type 2 diabetes [T2D], obesity, and cardiovascular diseases [CVDs]). Unfortunately, global FV consumption, particularly in Western nations, is significantly lower than recommended by public health agencies, such as the World Health Organization (WHO) and others, presenting major public health concerns.

In the UK, adults are reported to consume an average of 286g FV/day, compared to WHO recommendations of 400g FV/day. Average consumption in Europe is reported at 386g FV/day, and average consumption in the US totals 2.39 cups FV/day, approximating 325g FV/day.

The current gold standard for encouraging fruit and vegetable (FV) consumption is to convert the WHO daily FV recommendations into portion-based consumer guidelines (e.g., “consume five portions of FV daily”). The daily portions implicitly constitute specific, time-bound, and measurable goals, which some authors refer to as “SMART” (Specific, Measurable, Achievable, Relevant, and Time-bound) goals.

Unfortunately, previous investigations aimed at assessing the efficacy of these goals in the FV consumption context have met with two recurring drawbacks: 1. ‘Achievable’ and ‘relevant’ elements are rarely explicitly tested, and 2. Reports suggest that 5-a-day portion goals may not be perceived as ‘achievable’ in today’s increasingly fast-food-dependent world.

About the Study

The present study aims to address both these drawbacks by synthesizing the results of three independent studies aimed at elucidating the impacts of ‘achievable’ and ‘relevant’ elements in FV consumption.

The first study (Study 1) focused on the effects of ‘achievability’ of FV health promotion goals, wherein two versions of FV goals were recommended: 1. “Eat 5 FV today” (hypothesized as being less perceptually achievable), and 2. “Eat 1 more FV today.” The second study (Study 2) also evaluated achievability while explicitly testing the ‘relevance’ element through four FV goal recommendations: 1. “Eat 5 FV today for current benefit,” 2. “Eat 5 FV today for future benefit,” 3. “Eat 1 more FV today for current benefit,” 4. “Eat 1 more FV today for future benefit.”

The third study (Study 3) builds upon Study 2 by incorporating real-world FV purchasing scenarios. Study participants were British students, chosen due to previous research highlighting the demographic’s poor eating practices and low FV consumption.

Canteens serviced two large colleges (approx. 2,000 students), six small colleges (approx. 500 students), and a large city hospital (2 canteens) (Royal Bournemouth Hospital, serving the general public). Each canteen displayed between 1 and 3 of the 4 different health promotion messages for one week (in a 4-week measurement period), one at a time.

Studies 1 and 2 comprised 127 (38% male, mean age = 20.9) and 226 (28% male, mean age = 21.0) British university students, respectively. Study 3 used data from 10 canteens spread across Poole and Bournemouth, UK. Study 1 and 2 participants were randomly assigned to cases and controls. All three studies displayed their individual health promotion goals using easily visible 10 cm x 5 cm magnets provided to each study participant. However, in Study 3, the health promotion goals were displayed using posters in the canteens rather than magnets. Control participants’ magnets were blank (no goal). Interventions lasted 1 week.

FV consumption was assessed using participant-completed food diaries at baseline and intervention completion (Studies 1 and 2). Additionally, participants’ willingness to consume FVs in the future was assessed via questionnaires. FV consumption in Study 3 was assessed via canteen FV sales. Multiple regression models were used to investigate the impacts of each study treatment.

Study Findings

Study 1 highlights the benefits of providing goals in promoting FV consumption. Cases were found to consume substantially more FVs than their control counterparts. However, there was no statistically significant difference in FV consumption between the ‘Eat 1 more…’ and ‘Eat 5…’ goals themselves. Rather, the perceived ease of the goal—regardless of the specific wording—was positively associated with greater FV consumption. Notably, the participant-perceived importance of goals did not appreciably alter FV consumption outcomes.

Study 2 mirrors Study 1 in revealing that participants provided with ‘Eat 1 more…’ posters consumed slightly more FVs than those supplied with ‘Eat 5…’ goals, particularly in immediate FV selection and apple consumption, although not for all measures. Surprisingly, however, the relevance of the goals (current vs. future benefit) did not change FV consumption outcomes, highlighting the lack of importance of ‘relevance’ in FV promotion campaigns.

Study 3 demonstrated increased FV sales during goal promotion and for approximately one week after. Notably, however, neither achievability nor relevance altered study findings. In tandem with Study 1 (carried out at participants’ homes), these findings suggest that the ‘achievability’ goal is situational. It is also important to note that the observed increases in FV consumption and sales were relatively small (e.g., a 0.5 portion/day increase at home and about a 10% increase in canteen sales).

The researchers also observed that other factors, including liking for FV, positive attitudes, and self-efficacy, were associated with higher FV consumption, in line with previous literature.

Limitations of the studies include their focus on British university students, which may limit generalizability, and the modest effect sizes observed. The authors also note that their operationalization of “relevance” (current vs. future benefit) may not have been a strong enough manipulation to detect effects, and that other unmeasured factors, such as priming effects or individual differences, could have played a role.

Conclusions

The present study validates the benefits of setting goals to promote fruit and vegetable (FV) consumption. While the perceptual ease or achievability of meeting these goals can further improve FV consumption, this effect was smaller and sometimes not statistically significant, depending on the setting and outcome measured. Notably, the relevance of the goal does not improve FV consumption.

“Our findings demonstrate the facilitation of health behaviours by providing goals, and by providing goals that individuals feel that they can achieve. Based on these findings, we recommend the provision of goals, specifically easy/achievable goals, for encouraging FV consumption. Some benefits may yet be gained from an ‘Eat 1 more…’ as opposed to an ‘Eat 5 a day’ FV goal.”