Trendy juice diets beloved by celebrities and fitness fanatics may not be as healthy as they seem. PICTURE: Supplied

Trendy juice diets beloved by celebrities and fitness fanatics may not be as healthy as they seem.

Squeezing the juice out of a fruit or vegetable concentrates its calories, making it easier for people to over-consume and put on weight, heart doctors said. Eating plenty of fruit and veg is crucial for a healthy balanced diet. But the sugar in a solid piece of fruit or vegetable is released very gradually, because the body has to break down the cells in the food’s flesh.

Once fruit is squeezed the sugars become ‘free’ and it is more rapidly absorbed, according to the American College of Cardiology. A single glass of juice can contain as much as 13 g of sugar – nearly half an adult’s daily allowance. The college’s Prevention of Cardiovascular Disease Council last night published guidance on the best dietary patterns to reduce the risk of heart disease.

They said eating plenty of fruit, vegetables, whole grains and legumes would cut the risk, along with nuts in moderation. Meat, fish and dairy products should be eaten only occasionally, they said. But as part of their review, the authors condemned the misinformation surrounding ‘nutrition fads’ such as juicing diets, antioxidant pills and gluten-free diets.

Writing in the Journal of the American College of Cardiology, they said: ‘Each year patients are bombarded with new “miracle” diet books that claim to promote health, effect weight loss, and reduce disease risks.

‘Juicing of fruits and vegetables, often in combination with other foods and nutritional supplements, has become very popular, with no end of technologies to prepare the elixirs of health. However, the process of juicing concentrates calories, which makes it easier to ingest excessive energy.’

But Dr Sarah Schenker, of the British Fruit Juice Association, said: ‘Although the naturally occurring sugars have been released when a fruit is juiced, the juice does provide essential nutrients such as vitamin C, B vitamins and potassium as well as other natural substances with potential health benefits.

‘For people who are struggling with their five-a-day, it can be a useful option.’