Should fruit juice and smoothies count towards your five-a-day?

What role does fruit juice really play in a healthy, balanced diet, and can it affect mood? Dr. Oliver Shannon, Lecturer in Human Nutrition & Ageing, discusses the latest study on this topic.

Contents:

1. Do you get your five-a-day?
2. The fruit juice debate
3. Evidence for health benefits of juice
4. The study
5. What did the study find?
6. Take home recommendations

Do you get your five-a-day?

Fruits and vegetables are viewed by many as a cornerstone of a healthy, balanced diet.

Despite this, most of us don’t eat enough of them.

Indeed, in the UK, less than one in five people meet the Government’s five-a-day fruit and vegetable target. The reasons for this are complex, but include cost, availability (which can be poor in some settings such as workplaces), taste, risk of spoiling, and the limited time and skills to prepare them.

The fruit juice debate

Consuming 100% fruit juice – pure fruit juice with nothing added or taken away – or smoothies – blended fruit or vegetables – could help people achieve an optimal healthy intake of fruit and vegetables.

Fruit juice and smoothies are widely available, can be cost-effective, and many people find them palatable and enjoyable to consume. They require little or no preparation if purchased pre-made, and products from concentrate can be stored at room temperature for many months without spoiling.

However, the role of fruit juice and smoothies in a healthy, balanced diet has been the topic of much debate.

Some countries, such as the UK, allow one small glass (150ml) of fruit juice or smoothie to count towards the five-a-day target. However, recommendations vary considerably between different countries, and in some settings fruit juice and smoothies do not count at all towards fruit and vegetable intake targets.

Concerns about counting fruit juice towards these targets tend to relate to two key factors:

• The sugar content of fruit juice

Like whole fruit, fruit juice and smoothies are a source of sugar. The amount of sugar in fruit juice is identical to that found in the whole fruits in both amount and types of sugar.

However, the sugar in fruit juice and smoothies is defined as ‘free sugar’, which means that it’s assumed to exist outside, and so is ‘free’ of, the cell structures. In contrast, the sugar in whole fruit is viewed as being ‘intrinsic’ and held within the cell structure. Some believe that this could lead to different effects on health and the body. For example, higher intake of free sugars has been linked with an increased risk of tooth decay, though recent research has thrown this topic into debate, too.

• Juice contains less fibre

Fruit juice is known to contain less fibre than whole fruit and vegetables. The UK Government recommends consuming 30g/day, and this is important for, amongst other things, gut, cardiovascular, and metabolic health.

Evidence for health benefits of juice

Interestingly, despite these concerns, large reviews of the existing evidence suggest that consuming a small-to-moderate amount of fruit juice each day may have some health benefits, such as lowering blood pressure, improving blood vessel health, and lowering levels of inflammation, with limited evidence of negative outcomes.

This could be because fruit juice is rich in various micronutrients like vitamin C, potassium, and folate, and is a good source of health-promoting polyphenols and carotenoids. Despite having lower fibre than whole fruit, fruit juice also still often contains a small amount of fibre. For example, a glass of freshly squeezed orange juice typically contains about 0.4g fibre. Smoothies can contain even higher levels of fibre, given the entire fruit is blended without removing any of the fibre-containing pulp.

The study

Given the debate about the role of fruit juice and smoothies in a healthy, balanced diet, our study tested the effects of following five-a-day recommendations with or without fruit juice and smoothies.

We carried out a four week randomised controlled trial – a ‘gold standard’ form of scientific investigation. This was especially important as we wanted to provide robust evidence which was then rigorously peer-reviewed.

During the trial, participants were randomly assigned to receive different dietary interventions, with measurements taken before and after the study to see how effective each was.

One group of fourteen individuals (our control group) maintained their usual fruit and vegetable intake over the four week intervention period. A second group of fourteen were given support to increase their fruit and vegetable intake to meet the five-a-day targets by just consuming whole fruits and vegetables. A third group of fourteen people were encouraged to meet the five-a-day targets by consuming both whole fruit and vegetables and one portion per day in the form of fruit juice or smoothies.

We gave the participants in our two intervention groups £10 per week supermarket vouchers and an educational booklet to help increase their fruit and vegetable intake. Our control group also received the same financial support, but they were encouraged not to change their diet.

Before and after the four week intervention period, we measured fruit and vegetable intake, assessed mood for changes such as symptoms of depression and anxiety, and analysed gut symptoms. We also measured a range of blood markers to look at the effects of our interventions on the participants' metabolism.

What did the study find?

At the start of the study, our participants were consuming low levels of fruit and vegetables, approximately two servings per day. At the end of the study, both intervention groups exceeded the five-a-day fruit and vegetable recommendations, achieving significantly higher intake levels compared with the control group.

These findings are promising, and show that, with appropriate support, it is possible to help low habitual fruit and vegetable consumers to increase their intake levels.

Both interventions showed good acceptability and did not impact gut symptoms or metabolic biomarkers in blood samples.

One promising finding was that depression scores were significantly lower in the fruit and vegetable plus juice group compared with control. We also observed trends towards improved anxiety symptoms in both of our intervention groups, although these were not statistically significant.

Although these findings are exploratory, they are promising and suggest that increasing fruit and vegetable intake, including one portion per day of fruit juice or smoothie, could help improve mood in individuals who are usually low consumers of fruit and vegetables.

Take home recommendations

There continues to be controversy about the role of fruit juice in meeting fruit and vegetable intake targets. However, our study suggests that inclusion of one daily glass of fruit juice in five-a-day recommendations over a four week period does not adversely impact gut symptoms or markers of metabolism, and could even favourably impact mood.

Next, we hope to carry out longer and larger studies, including in individuals who have poor mental wellbeing, rather than generally healthy participants like in this study. This could allow us to determine if increasing intake of fruit and vegetables - including with one daily portion of fruit juice - might be an effective strategy for improving symptoms in people living with depression.

A note on the funder, our team, and the scientific publication

This research was funded by a research grant from the Fruit Juice Science Centre.

The academic researchers carrying out this study were responsible for the study design, data collection, analysis, interpretation, writing of the report, and the decision to publish.

The research team included Dr. Oliver Shannon and Dr. Anthony Watson, who led the study and secured the funding to support it. Dr. Courtney Neal conducted the data collection and analysis and drafted the scientific journal article alongside Dr Shannon and Dr Watson. Professor Georg Lietz and Dr. Kirsten Brandt provided specialist expertise to support laboratory analyses of blood samples and helped further shape the journal article.

You might also like...

• explore the study’s findings in leading nutrition journal, the British Journal of Nutrition, published here: ‘Including fruit juice and smoothies within 5-a-day fruit and vegetable intake recommendations: a randomised controlled trial investigating impact on levels of intake, mood and markers of health’
• find out more about the author and principal investigator of the study, Dr Oliver Shannon, Lecturer in Nutrition and Ageing at Newcastle University
• explore the interdisciplinary world of Newcastle University’s Human Nutrition Research Centre
• find out more about research team co-lead, Dr Anthony Watson, Lecturer in Human Nutrition at Newcastle University
  

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