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• Fruit juice is often advocated as an easy way to get one of your five a day.
• However, it is high in sugar, and although it contains vitamins and some micronutrients, it does not have the dietary fiber of whole fruit.
• Now, an analysis of studies has found that drinking a glass of fruit juice every day is linked to weight gain in children and some adults.
• The study shows an association between fruit juice and weight gain but cannot show causation.

Fruit juice provides vitamins, minerals and polyphenols in an easily accessible form, and is part of the daily diet of many people, providing one of the recommended five a day (400g) of fruit and vegetables.

However, many people are concerned about the sugar content of fruit juice — a 250 ml serving of orange juice contains 22 grams, or 4.5 teaspoons of sugar — but studies suggest that adverse health effects, such as tooth decay and some weight gain, are outweighed by the health benefits.

To investigate whether fruit juice causes weight gain, teams from Toronto and Boston reviewed 42 studies into the effect of drinking 100% fruit juice — pure fruit juice with no additives — daily.

They found that in children, there is a positive association between daily drinking of fruit juice and weight gain. In adults, no similar association was seen except in studies that were not adjusted for total energy intake.

The study is published in JAMA Paediatrics.

“The study’s findings suggest a potential link between fruit juice consumption and weight gain, but the association is small, and the evidence is limited. […] It’s important to remember that correlation doesn’t equal causation. Other factors, like overall diet and physical activity, likely play a larger role in weight gain than moderate fruit juice intake.”
— Daniel Ganjian, M.D., F.A.A.P., board certified pediatrician at Providence Saint John’s Health Center in Santa Monica, CA, who was not involved in the study, speaking to Medical News Today.

A range of fruit juices

In all the studies analyzed, participants consumed at least one 8oz serving (or equivalent) of 100% juice each day. The studies looked at a range of fruit juices — pomegranate, berries, tart cherry, apple, citrus, or grape juice — and compared them with standard diet alone, water, or diet or low calorie drinks.

Some were prospective cohort studies, and others were randomized control trials. Not all of the studies assessed total energy intake of the participants, which may introduce an element of inaccuracy.

The researchers performed several statistical analyses on the data to assess whether there was any link between daily fruit juice and weight.

How daily juice drinking affects weight

The effect of daily fruit juice on weight varied depending on the age of the participants. These effects were greater in children than in adults.

“Our findings indicate that 100% fruit juice consumption was associated with weight gain in children, especially among younger children. Among prospective cohort studies in adults, we found that 100% fruit juice was associated with weight gain among studies that did not account for intake of calories in their statistical analyses (unadjusted for calories), suggesting that excess calories play a role in this association.”
— Michelle Nguyen, Ph.D. candidate and study lead author, Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, speaking to MNT.

Weight changes, while small, varied with the type of juice ingested. Some were associated with weight gain, and others with some weight loss, as Kelsey Costa, a registered dietitian nutritionist and national media spokesperson for Dietitian Insights, who was not involved in the study, told MNT:

“Despite there being no substantial disparities in weight changes across different juice types in this study, an emerging trend favored juices derived from so-called ‘superfoods’.”

“Juices such as pomegranate, various berries (like goji, barberry, bilberry, and currant), and tart cherry demonstrated a tendency towards weight reduction. Conversely, juices like apple, citrus, and grape tended to contribute to weight gain,” Costa added, cautioning: “However, even with ‘superfood juices’ like pomegranate, research indicates that moderation may be important.”

Is fruit juice bad for children?

The observed weight gain in children may be because a glass of juice makes up a larger proportion of their daily energy intake than it does for an adult, and they are more likely to drink apple, citrus and grape juices which were associated with weight gain in the analysis.

So, to ensure that children get the essential nutrients from fruit, it is better to encourage them to eat whole fruits rather than drink juice.

Costa also advocated not to introduce fruit juice to children under the age of 6 to avoid “fostering a preference for sweet flavors” which might lead to “’picky’ eating patterns and a greater inclination towards sugary food and drinks.”

She suggested that, instead, parents and carers might offer: “Healthy alternatives that provide similar vitamins to fruit juice for children […] whole fruits like apples and bananas, vegetables like carrots and celery, and hydrating beverages like water infused with slices of fresh fruit, providing just a hint of natural sweetness.”

Can juice be part of a healthful diet?

Fruit juice may cause weight gain because of the extra calories it provides, so a small glass each day is unlikely to increase a person’s weight. However, nutritionists advise that whole fruits will provide more of the vitamins and minerals, plus dietary fiber and beneficial bacteria, which are essential for gut health.

Kelsey Costa explained why whole fruits are preferable:

“Compared to whole fruits, fruit juices contain less dietary fiber. Dietary fiber slows down the absorption of sugar, so with fiber absent in fruit juice, the naturally occurring sugar (fructose) is quickly absorbed by the liver.“

How fruit juice may lead to weight gain

“When too much fructose is consumed, the liver can convert it into fat, leading to the production of certain types of fats known as very low-density lipoproteins and triglycerides. To put it simply, when the liver is overloaded with fructose from the juice, it turns the excess sugar into fat, which contributes to weight gain.”
— Kelsey Costa

Dr. Ganjian agreed, adding: “Liquid calories tend to be less satiating than calories from solid food, potentially leading to overconsumption.”

A recent study suggested that fructose might be the factor that underlies the huge increase in the number of people with obesity, so limiting your fruit juice consumption could be an easy way to reduce your intake of fructose.

You can enjoy fruit juice without it causing weight gain, but Michele Nguyen advised: “We suggest that whole fruit should be consumed over fruit juice. In children, our findings are in support of AAP guidelines of fruit juice consumption — [no more than] 4 ounces per day for children 1-3 years, 4 to 6 ounces for children 4-6 years, and less than 8 ounces for children 7-18 years. In adults, no more than 8 oz per day.”