The truth is that fruit juice, even if it is freshly pressed 100 per cent juice, is little more than sugar water. Yet many Americans believe that juice is good for them. In one survey of parents of young children, 1 in 3 believed that juice was at least as healthy as fruit.
We are inundated with the message that juice is healthy. Juice bars abound in gyms, spas and health food stores, and government programmes supply large quantities of juice to low-income children and pregnant mothers.
The commercial juice industry is happy to build on this idea, like POM Wonderful's tagline "Drink to your health" or Juicy Juice's containers extolling the (mostly added) 120 per cent of recommended daily vitamin C in their products.
Although the internet is busy laughing at news of the Juicero juicing machine that doesn't actually need the $400 WiFi-enabled machine, what people should really be talking about is a much simpler fact - the product takes healthy fruits and vegetable and makes them much less healthy.
At first glance, it is reasonable to think that juice is healthy: whole fruit is healthy, and juice comes from fruit, so it must be healthy, too.
But when you make juice, you leave some of the healthiest parts of the fruit behind. The skin on your apple, the seeds in your raspberries and the membranes that hold the orange segments together - they are all good for you. That is where most of the fibre, as well as many of the antioxidants, phytonutrients, vitamins and minerals, are hiding.
Fibre is good for our gut; it fills us up and slows the absorption of the sugars we eat, resulting in smaller spikes in insulin. When our bodies can no longer keep up with our need for insulin, type 2 diabetes can develop.
Finally, when we drink our calories instead of eating them, our brain doesn't get the same "I'm full" signal it does from solid food, even though we wind up consuming far more calories in the process. Whereas an orange may contain 45 calories, a 240ml glass of orange juice contains 110 calories, and a large kale, banana and orange smoothie at a leading juice chain contains more than 600 calories.
You might feel full immediately after drinking a glass of juice or a fresh smoothie, but that sensation goes away quickly as the liquid empties out of your stomach, and many of those 600 calories you just drank don't get counted in your body's internal calorie counter, contributing to that bulging waistline the gym was supposed to help fix.
Our perception of juice needs a radical makeover, starting with kids. Juice comes in easy single serving, shelf-stable packages that parents don't hesitate to give to kids anywhere.
Yet children don't need juice for nutritional purposes, and most juice boxes contain more than the 120-180ml maximum recommended by the American Academy of Pediatrics for daily consumption by kids under 6.
In fact, kids who drink juice regularly are shorter and heavier than kids who rarely drink juice, probably because they consume less milk, which young children need for healthy growth. The perception that juice is good for kids comes in part from the Women, Children and Infants Supplemental Food Programme, better known as WIC, which provides food assistance to 25 per cent of all pregnant women and half of all children in the US at some point in the first five years of the child's life.
Although the programme has helped to improve birth outcomes and cognitive development in participants, it needs revision.
The WIC programme supplies a very narrow range of foods deemed healthy for pregnant women and growing children. This includes healthy staples such as milk and eggs, but surprisingly also includes nine litres of juice a month.
When the programme started in the 1970s, there wasn't an obesity epidemic, and undernutrition was a major concern. In that context, giving juice rather than fresh fruits and vegetables, which also didn't have the year-round availability that they do now, may have made sense.
Today, it just feeds the false perception that juice is a healthy choice.
So what can we do to start fixing this problem? First, recognise juice for what it is: a treat.
It doesn't belong at your breakfast table or after your workout at the gym. Next, get juice out of your children's lives. Ditch the juice boxes in favour of water or shelf-stable milk boxes. Not only does milk contain about a third of the sugar of juice, it's also a great source of the protein, calcium, vitamin D and magnesium that growing kids need.
Make sure that their day care or after-school programme is following current guidelines and only serving milk or water. Finally, the Institutes of Medicine recently released recommendations for revisions to the WIC programme, which included a reduction in the juice allowance. Write to the Department of Agriculture and let them know that you support reduction/elimination of juice in the WIC programme.
We can't solve the diabetes and obesity epidemics with one simple move, but rebranding juice from health food to treat would be a major step in the right direction.
• Heather Ferris is assistant professor of medicine in the division of endocrinology and metabolism at the University of Virginia in Charlottesville.
• Elvira Isganaitis is assistant professor of pediatrics at the Joslin Diabetes Centre in Boston.
• Florence Brown is assistant professor of medicine and director of the Diabetes in Pregnancy Programme at the Joslin Diabetes Centre in Boston.
