While fruits and vegetables are often grouped together, is one group of foods healthier than the other? And, if so, should this be considered in the word order of public health messaging (i.e., 'fruits and vegetables' vs. 'vegetables and fruits'?).
Introduction
‘Eat your fruits and vegetables’—it’s a message we know all too well. And for good reason: in 2017, diets low in fruits and vegetables were estimated to cause nearly 4 million deaths worldwide (1). This helps to explain why fruits and vegetables feature prominently in food-based dietary guidelines across the globe, and are often recommended to make up about half of the diet (Figure 1).
Figure 1. Canada’s food guide. As you can see, fruits and vegetables are recommended to make up about half of the diet (here, the plate refers to the overall diet. This does not mean that half of each meal needs to be fruits and vegetables). Interestingly, this food guide uses the word ‘vegetables’ first in the phrase.
Because fruits and vegetables are distinct food groups, it is possible that one food group is, on the whole, preferable to the other in terms of healthfulness. In this case, there is a reasonable argument to reorient how we discuss these foods, i.e., when we communicate, should we say ‘fruits and vegetables’ or ‘vegetables and fruits’?
Is Word Order Important?
According to Surprisal Theory from psycholinguist Roger Levy (2), when we encounter unfamiliar or unpredictable phrases, such as ‘vegetables and fruits’ as opposed to 'fruits and vegetables', the increased mental processing time necessary to understand the terms could help to entrench the phrase in our memory. Could this cause people to think a little deeper about their food choices, if even subconsciously? I’m not sure, but if we can decide which food group is more important from a public health point of view, perhaps it warrants first mention in the phrase.
Fruits vs. Vegetables
Luckily for us, a group of researchers from Stanford have compared the healthfulness of fruits and vegetables (3). To do so, the researchers identified the most commonly consumed fruits and vegetables in the US (Table 1), and compared their nutrient composition and quality per 100 calories. To compare nutritional quality, researchers compared the selected fruits and vegetables by their Aggregate Nutrient Density Index (ANDI) and NuVal scores (3). In brief, the ANDI divides the total nutrients (i.e., 35 vitamins and minerals and other nutrients like fibre and antioxidants) in the food by the number of calories per serving, and ranges from 1–1,000, with 1,000 being most nutritious (3). The Nuval score uses an algorithm that incorporates 30 different nutrients, protein quality, fat quality, glycaemic load (i.e., how much a food increases blood sugar), and energy density, and ranges from 1–100, with 100 being most nutritious (3).
Table 1. Top 10 most consumed fruits and vegetables in the US (3).
Fruits | Vegetables |
Banana | Potatoes |
Apple | Tomatoes |
Watermelon | Onions |
Grapes | Iceberg lettuce |
Strawberries | Green bell pepper |
Orange | Carrots |
Avocado | Cabbage |
Peach | Cucumber |
Pear | Celery |
Mango | Broccoli |
Astute readers may argue with the classification of fruits and vegetables in Table 1. For example, tomatoes, bell peppers, and cucumbers are botanically classified as fruits. Despite their botanical classification, it was their culinary classification that was used for categorisation in this paper (3).
Results
The average ANDI score for vegetables was 227, whereas fruits scored 74 on average, meaning vegetables came out on top in this head-to-head battle (3). When comparing food groups using the NuVal score, both fruits and vegetables scored similarly high (i.e., >90/100) (3). In terms of specific nutrients, the vegetables provide significantly more folate (vitamin B9), iron, magnesium, calcium, potassium, and fibre than fruits (per 100 calories, not per serving). However, the fruits contained more than double the antioxidants of the vegetables, on average, with strawberries leading the way for fruits, and broccoli for vegetables (3).
What’s perhaps more important than nutrient and antioxidant composition is how these foods impact death and disease risk. Therefore, the researchers also reviewed the literature to identify whether fruits or vegetables were more consistently associated with a reduced risk of death, heart disease, type 2 diabetes, or cancer in long-term, large-scale, prospective cohort studies (3). Overall, most studies observed reductions in risk for most of these outcomes for greater fruit consumption and greater vegetable consumption (3). However, a greater number of significant associations were identified between vegetables and reduced risk of these health outcomes (relative to fruits) (3).
Summary
In the battle of these 2 healthy food groups, vegetables seem to come out on top. With this in mind, perhaps public health messaging should shift from ‘fruits and vegetables’ to ‘vegetables and fruits’. Indeed, certain national dietary guidelines (e.g., the US and Canadian dietary guidelines) have made this switch, which may be in response to current consumption levels of vegetables being lower than fruits (at least in the US) (3). With all of this said, we must not lose the forest for the trees: most people would benefit from increasing their vegetable and fruit intakes, and any minor differences between the healthfulness of these food groups should not distract from that important message.
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Patrick Elliott, BSc, MPH
Health and Nutrition Science Communication Officer at Training121
Email: [email protected]
Instagram: @just.health.info
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References
(1) GBD 2017 Diet Collaborators. Health effects of dietary risks in 195 countries, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017. Lancet. 2019;393(10184):1958–72. Available at: https://www.thelancet.com/action/showPdf?pii=S0140-6736%2819%2930041-8
(2) Smith NJ, Levy R. The effect of word predictability on reading time is logarithmic. Cognition. 2013;128(3):302–19. Available at: https://www.sciencedirect.com/science/article/pii/S0010027713000413
(3) Offringa LC, Stanton MV, Hauser ME, Gardner CD. Fruits and Vegetables Versus Vegetables and Fruits: Rhyme and Reason for Word Order in Health Messages. Am J Lifestyle Med. 2018;13(3):224–34. Available at: https://pubmed.ncbi.nlm.nih.gov/31105482/
Technical Terms
Antioxidants: Substances that help protect your cells from damage caused by harmful molecules called free radicals. They can be found in many fruits and vegetables, and examples include vitamin C, beta carotene, and flavonoids.
Statistical significance: This is a term to describe the likelihood of whether a finding in a study is a ‘real’ finding, or if it is the result of chance. Statistical significance is denoted by a p-value, which is usually set at a significance (alpha) level of 0.05. This means that if a result is significant at this level (p≤0.05), we can say that the probability of getting a value as or more extreme than the observed value (under the assumption that the null hypothesis is true) is less than 5%. In other words, it is more likely that this finding is not the result of chance than if the p-value was >0.05 (although this is not always the case).
Prospective cohort study: A type of study where a group of people (the cohort) is followed over time to see how certain factors (like diet, lifestyle, or medication) affect their health outcomes (e.g., risk of death). Researchers collect data from the participants at the start and then continue to collect information at various points in the future to observe any changes or developments in their health. These types of studies are crucial for helping us to understand the healthfulness of dietary patterns, foods, and nutrients.
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