A glass full of medicine?

Fact: everyone needs a balanced diet with the necessary amounts of nutrients - including vitamins and minerals - to maintain good health. Fact: liquids of different kinds can play a part in that diet. But does that mean that we should be looking to liquids to make us healthy and happy?

Fact: everyone needs a balanced diet with the necessary amounts of nutrients - including vitamins and minerals - to maintain good health. Fact: liquids of different kinds can play a part in that diet. But does that mean that we should be looking to liquids to make us healthy and happy?

The answer depends on whom you ask. Ask doctors, dieticians and nutritionists, and the response is along the lines of: "Go ahead if you want to. So-called healthy drinks are unlikely to do you any harm." If you ask people who sell the drinks, you'll hear something like: "Yes! Absolutely! But don't ask us for evidence of specific health benefits, because we can't give you any."

"Healthy drinks" fall into three categories: fruit juices, often fortified with herbal extracts; water; and good old alcohol. The health claims made for alcohol are pretty quickly dealt with. WHO decided in 1997 that a drink every other day reduces the risk of coronary heart disease. Other authorities think that one or two units a day may help protect against heart disease and strokes. The list of protective components in wine and, possibly, beer that confers these benefits seems to change by the month, and some scientists think that beer is as effective as wine. A couple of years ago the buzzword was resveratrol, but there is also talk about quercetin and epicatechin, two other antioxidants.

The second healthy drink, water, is also relatively straightforward. You need six or eight glasses of fluid a day, and as you've probably decided which brand of bottled water you like, I won't come between you and your fashion-victimhood. Just drink enough of the stuff. Dietician Nigel Denby points out, however, that some of our fluid intake can come from coffee, tea and soft drinks. The water bottle in the handbag - that must-have accessory of the modern age - is unnecessary unless you're taking vigorous exercise. And if you decide that you need Oxygizer, an oxygenated water from Austria containing 150mg of oxygen per litre (as opposed to 5mg to 8mg in tap water), then be my guest. This latest marketing water-wheeze costs £1.55 for 500ml at Selfridges.

Juices present a clearer case for the health-conscious - though you have to take the labels with a grain of low-sodium salt substitute. Fruit is vitamin-rich, and if the vitamin content has been preserved in whatever fruity preparation you're ingesting, you'll get the benefit. A 100ml bottle of Tropicana Pure Premium orange juice, for instance, contains 40 per cent of the RDA for vitamin C and 13 per cent for the B vitamin folic acid. And oranges aren't even the best source of either: guava and blackberry are better for vitamin C; pomegranate and banana both have more of the B vitamins. If you eat or drink a good variety of fruits, and plenty of them, you should do just fine.

But it's the juicy road to nutritional nirvana that excites many consumers, and there's no shortage of companies vying to meet our requirements. Juice is easy. It's fast. If it's made well, it's even tasty. The smoothies and other drinks made by PJ's and Innocent are of outstanding quality, and, if you can bear the price, they can help achieve the magical "five a day" target (five portions or fresh fruit and veg a day).

It's when the healthy-drinks industry goes into detox mode that it loses me. Detox is one of the buzzwords of the moment on the fringes of the health business, and it is a load of codswallop. "The whole concept is basically irrational and unscientific," says Amanda Wynne of the British Dietetic Association. "If we had all these toxins in our bodies, we'd feel ill." Self-styled detox drinks are healthy foods, she says, "and there is no harm in them. But they are not going to give you any magical effects."

I love these drinks for the transparently ludicrous claims they make - claims that pander to precisely the kind of magical thinking that Wynne dismisses. Take Innocent's Natural Detox. On its website it says: "You know what it's like - all of your best-laid plans ruined by wine, bar snacks... leading to a slightly sore head and sluggish demeanour... So we thought we'd design a natural detox smoothie, to help give your body a break from the bad stuff, and so it can get rid of all of the filthy toxins that seemed like such a good idea at the time. Lemon for vitamin C, honey for natural antioxidants and energy, along with some ginger to help cleanse, purify and make it taste nice. It's a bit like a posh spa in a bottle." Utter tosh. If you lay off the Chardonnay, chips and chilli for a while, your kidneys and liver will soon clear away any residues. By all means spend a fortune on an Innocent drink, but don't get caught up in the morass of mystical thinking.

And if a drink proclaims its addition of ginger, ginseng or any other herbal remedy, be sceptical. "It's probably a homeopathic dose, not a clinical dose," says Catherine Collins, a dietician at St George's Hospital, London. She gave me a detailed analysis of PJ's Daily Detox to illustrate the point. The company describes this as "mandarin, dragonfruit and mashed bananas blended with nature's own cleansing milk thistle and natural ginger - and not forgetting loads of vitamin C". Collins points out that the doses of milk thistle and ginger are well below clinical levels, and also that "adding herbal extracts back to a 'pure' fruit juice drink is not exactly 'natural'".

It's a pleasure to note that in the right sectors of the catering trade, detox silliness can produce happy results. Tony Conigliaro, of new London restaurant and bar Shumi, is offering as a "January detox" what he calls an Apple Mojito: mint and sugar crushed in a tall glass, 10ml each of lemon and lime juice, half-fill with crushed ice, top up with 100ml clear apple juice then crushed ice, and stir. Garnish with mint, a slice each of lemon and lime. Talented people like Conigliaro had better watch out. This kind of resourcefulness could end up giving detox a good name.