This week, it looked as if fruit juice might finally lose its claim to healthiness and be put into the same category as fizzy drinks. It emerged that a headteacher, Elizabeth Chaplin, who runs Valence primary school in Dagenham, wrote to parents about a new rule to confiscate juice cartons from children's lunch boxes. Instead, pupils would only be allowed to drink water.

Days earlier, Susan Jebb, a government advisor and head of the diet and obesity research group at the Medical Research Council's Human Nutrition Research unit at Cambridge University, told the Sunday Times that the government's official advice that a glass counts towards your recommended minimum five-a-day servings of fruit and vegetables should be changed.

"Fruit juice isn't the same as intact fruit and it has as much sugar as many classical sugar drinks," said Jebb, who has stopped drinking juice. "It is also absorbed very fast, so by the time it gets to your stomach your body doesn't know whether it's Coca-Cola or orange juice, frankly. I have to say it is a relatively easy thing to give up. Swap it and have a piece of real fruit. If you are going to drink it, you should dilute it."

This comes on top of a year or so of stories about the high sugar content of fruit juice. The same US scientists who warned about the use of high-fructose corn syrup in fizzy drinks have now turned their attention to juice. "Fruit juice and smoothies are the new danger," Barry Popkin, professor of nutrition at the University of North Carolina, told the Guardian in September. Work by Dr Robert Lustig – whose book Fat Chance: the Bitter Truth about Sugar received much attention last year – and studies such as one published in the British Medical Journal in the summer, which found fruit juice is associated with an increased risk of type 2 diabetes, are starting to make people realise that fruit juice may not be as wholesome as they once believed.

So why is fruit juice still being pushed as a healthy option? "You can't trust government health advice," says Joanna Blythman, author of What to Eat. "They have the same advice that they've been recycling for 50 years and rarely change it. It's embarrassing to admit they've made a mistake."

Does she drink juice? "I don't, really – not in any great quantity," she says. At one point, she says, in the late 1980s and early 90s, she was "a very enthusiastic orange juicer. I remember coming back from the States, where everyone juices like mad, and I got a juicer. Then over the last couple of years there has been more and more evidence that sweet juices are basically just fructose, and have a similar effect on the body to fizzy and soft drinks in terms of sugar."

The juice industry has long enjoyed a healthy image. Anything to do with fruit, says Blythman, "has always been used to put a halo of health around dubious products that don't merit it. That's business as usual for the food industry."

For all their reliance on phrases such as "100% pure" and "pure squeezed", many of the big commercial orange juice manufacturers make a processed product, as detailed by Alissa Hamilton in her 2009 book Squeezed: What You Don't Know about Orange Juice.

In the early 20th century, juice was mainly sold in cans. During the second world war, the US government commissioned scientists to develop a product that would supply vitamin C to soldiers overseas. "That's when research into developing a frozen concentrate that people would actually like started," says Hamilton. Until then, it had been fairly tasteless – the concentrating process removed the water, but also the natural chemicals that gave orange juice its taste. "They started adding fresh juice to the concentrate and that made it taste good. The discovery was too late for the war, but after the war that's when orange juice started to become really popular."

One primary school in Dagenham is to start confiscating fruit juices from children's lunch boxes. Photograph: Kidstock/Getty Images/Blend Images

However, as the market grew, it was becoming too expensive to use fresh juice to add flavour back to concentrate. "They developed the technology around the 1960s to capture and break down the essences and oils that were lost when the juice was concentrated, and came up with these things called flavour packs."

Producers of pasteurised orange juice began storing their juice in vast tanks. In order to keep it "fresh", the product had to be stripped of oxygen. Once this had been done, the juice could be stored for up to a year. The only problem was that this process also removed much of the taste. "You need flavour packs to make it taste like anything we know as orange juice," says Hamilton.

So, does she still drink juice? "I actually never did," she says. "I try to eat the whole thing. If I have an orange, I don't even stop at the fruit – I eat the pith, the peel. Juicing anything would not be my choice."

For most of us it is, though, and it is not obvious that any of the sugar scare stories are affecting the fruit juice market yet. In its latest report, the research company Mintel found that 83% of people drink fruit juice, a juice drink or smoothie at least once a week. It also estimates that the market will grow by 13% by 2018. It found 34% of consumers were concerned about the amount of sugar, but "a striking 76%" believed juice and smoothies to be healthy.

As part of its end-of-year "top products" survey, the retail trade journal the Grocer found a mixed picture for juice brands. The leading brand, Tropicana, experienced a downturn in sales of 5.4% throughout 2013, though sales of Innocent smoothies, owned by Coca-Cola, were up more than 7%. However, Innocent was one of the brands highlighted last year as containing high levels of sugar: a 250ml serving of its pomegranate, blueberry and acai smoothie contains 34g of sugar, around the same as a 330ml can of Coke.

"I think the current coverage about fruit juice and sugar will have an influence on consumers," says Heidi Lanschützer, food and drink research analyst at Mintel. "The question is whether it's a short- or long-term impact." She says this will depend on how ongoing the coverage is, and whether more schools ban juice, though the biggest impact will be if the government takes Susan Jebb's advice and removes it from the five-a-day list. This, she says,"is one of the market's biggest selling points – if the market is not allowed to use that any more, that will definitely have an impact."

Not everybody is racing to demonise juice just yet. "It's about portion size. 150ml of fruit juice is perfectly acceptable as one of your five-a-day," says Azmina Govindji, dietitian and spokesperson for the British Dietetic Association. "But we would suggest you have it with a meal so it doesn't make your blood sugar go up too quickly. I think the difficulty comes when people think of fruit juice as being a really healthy drink and having half a pint, or having it throughout the day, or where children are being brought up on large amounts.

"The key message is that small amounts – a 150ml glass is quite small – as part of a healthy varied diet is fine. You get fluid and vitamin C but you need to be aware that it does contain sugar. If you can, always choose fresh fruit and veg [over juice]. You're going to get fibre, more nutrients and you're likely to have fewer calories."

Does she think the advice on juice being part of the five-a-day will change? "I think what needs to change is advice on portion size."

Blythman, meanwhile, understands that the mixed messages about juice are perplexing for consumers. "People are thoroughly confused," she says. "But I think [growing awareness of sugar levels] will have an effect. The simplest way to put it is: eat whole fruit, don't drink juice."

The rise and fall of our favourite foods – what's in:

Halloumi: Britons have become the biggest European consumers of the rubbery, squeaky white cheese outside of Cyprus. Tesco's halloumi sales rose by 35% during 2011 and 2012, while Waitrose reported a 104% increase. "I don't think it was one event that explains halloumi's popularity," says Louis Constantinou, director of the Cypressa food company, founded by his uncles in the 1960s, which now supplies halloumi to supermarkets. "It got exposure by celebrity chefs. It's a versatile product in the sense you can do lots with it – grill it, eat it as it is."

Hummus: Waitrose claims to be the first supermarket to have stocked hummus, around 20 years ago. Now, says Jonathan Moore, the supermarket's executive chef, they have around 19 varieties. "It has become a staple – people are using it on bread instead of butter." One recent survey found 41% of Britons had a pot of hummus in their fridge, and the British taste for the chickpea paste, which originates in the Middle East, is worth around £60m a year.

Sweeter apples: Theresa Huxley, apple technologist for Sainsbury's, says consumers are looking for sweeter apples. The supermarket is stocking a record 57 varieties of apple, including more British varieties than before. "Royal Gala remains our most popular variety, and that's a very sweet one, but there are lots of new varieties that are becoming more and more popular: Jazz, which has a peardroppy flavour, and Rubens which has tones of melon, and Zari, which is a sweet, juicy apple."

Bottled water: Environmentalists have long tried to wean us off our attachment to bottles of water, and for a while it looked like it might work – in 2009 sales fell by 9%. However, as a report for the Grocer put it last month, "all is forgotten". Last year we drank 8.7% more bottled water than in 2012.

Ceviche: The decreasing cost of international travel and the ability of a growing number of people to experience other cultures and cuisines, says Moore, have had a huge influence on our national palate. Middle Eastern influence has been strong, thanks to chefs such as Yotam Ottolenghi, but Moore is also looking at food inspired by South America, especially ceviche – raw fish cured with citrus juices. "Ceviche is, for me, the sushi of 20 years ago. Twenty years ago, would anyone have said sushi was going to be this big in the UK?"

And what's out:

Meat: According to one survey published in November, a quarter of Britons are eating less meat, with a further 34% saying they would consider eating less. Just 2% reported eating more than they had previously. The survey was conducted for Eating Better, an alliance of groups including Friends of the Earth, launched in summer 2013 to encourage people to eat less meat. It attributed the results to the fallout from the horsemeat scandal, and growing awareness of the environmental impact of rearing animals for meat. Others blamed falling sales on rising costs – according to the Financial Times last month [http://www.ft.com/cms/s/0/b41bd746-61a3-11e3-916e-00144feabdc0.html#axzz2nnzEoiNl], British beef prices are at record highs, and sales of the most expensive cuts, such as roasting joints, are down by a quarter on the previous year.

Builders' tea: "The mainstream tea category has lost its sparkle," Neil Manders, Twinings' commercial director, told the Grocer recently. In September, the trade journal published a report on the hot drinks market. It found that people are moving away from traditional tea and – if they are not drinking coffee instead – towards fruit and herbal varieties, and green tea (sales are up 15% and 19% respectively). In a more recent report, the Grocer found volume sales of tea were down 6.1% in 2013, a bigger decline on the previous year.

Whole lettuces: The 1980s were the glory years for the iceberg lettuce, but over the last few years sales of whole lettuces have been falling [http://www.telegraph.co.uk/finance/personalfinance/8347648/Era-of-iceberg-lettuce-is-over.html] as consumers developed a taste for more unusual leaves and the popularity of ready-washed bagged salads took off. In a final indignity, last year the Office for National Statistics removed the round lettuce from its "typical" shopping basket to illustrate retail prices, though the iceberg lettuce remains. For now.