Should you boost your juice?

Nutrients in fruit give you a natural boost. But are vitamins being squeezed out of your glass of OJ? Nutritionist Catherine Saxelby gets to the core issues.

Watermelon, mint and beetroot. Apple, capsicum and celery. Peach, guava and pineapple. Orange and carrot. With a shot of wheatgrass, guarana or perhaps ginseng. There are many combinations on offer, all claiming to have health benefits. But is juice really that healthy? And does buying fresh juice count as one's daily serve of fruit and veg?

Commonly asked questions

Juice has no fat or sugar, and is fresh and healthy. Does that make it ok for me to drink?

Freshly-squeezed juice extracts nutrients from fruit and vegies so you get vitamin C, folate, beta-carotene (converted to vitamin A in the body), vitamin B1, niacin, vitamin K, plus potassium and magnesium. Juices are better than sugary drinks that don't have any nutrition; soft drinks or cordial, for example. Juice may be low in fat, but it's still a concentrated source of kilojoules and fructose (fruit sugar) so there's no need to drink a litre of juice a day.

Since juice is 100% natural, it's not at all fattening, right?

One glass of juice contains four to five pieces of whole fruit. Think about how much you put into the juicer to produce a glass. You could easily juice up two oranges, an apple and half a mango – that's a lot of fruit.

Certain fruit like pineapples, grapes and lychees are high in natural sugar (fructose) and can contain a surprising amount of kilojoules.

Like many modern foods, juice is best in moderation. Alternatively, it's a good idea to dilute juice with water or sparkling mineral water. Or fill up the glass with ice cubes first then pour in the juice.

Is it true that juice doesn't have any fibre?

Yes, and this is the one big drawback. Fibre 'bulks up' in your stomach and prevents you overeating. Once it is juiced, the intact structure of a piece of fruit is gone and, with it, the fibre and 'nature's brake' to over-consumption is removed.

An often-quoted study from the 1980s compared whole apples with apple puree and apple juice. It reported that people who ate the apples felt fuller sooner and consumed less kilojoules (kJ) than the people on the puree and juice.

Look at this comparison:

• A 650ml bottle (2 1/2 cups) of apple juice has zero fibre and 1300kJ (309 calories) and can be sipped in two minutes.
• A medium 200g apple has 3g fibre and 300kJ (71 calories) and takes 10 minutes to eat. Think of all the chewing you do!

That's the problem. A large juice – typical of what's on offer at juice bars – takes a fraction of the time to drink because there's no fibre.

There are juices available that have added pulp, which gives you more fibre. But it's still not as good as a piece of fruit. If you're juicing at home, you can add the pulp back in your glass.

Can juice contribute to the recommended two serves of fruit I'm supposed to eat every day?

Nutritionists recommend two pieces of fresh fruit a day plus five serves of vegies. However, this equals a small amount of juice – half a cup (125ml) of juice generally contains two whole serves of fruit!

Drinking lots of 100% freshly-pressed juice is a way to put on weight. They may be 'healthy kilojoules' in that 100% juice, but they are still kilojoules – and you can all too easily pile on the kilos if you're sedentary (as most of us these days are) and don't exercise enough to burn it off.

Isn't it better to simply eat the whole fruit rather than making a juice and then drinking it?

That's exactly what nutritionists suggest. We would prefer you drink water if you're thirsty – no kilojoules there – and eat a piece of fruit.

Should I drink fruit juice when I go on a detox?

Fresh juices are part of the raw foods philosophy, which has been recommended by natural health practitioners since the 19th century.

Juices are often promoted as part of detox regimes – you'll see claims that they can 'cleanse the digestive system', 'draw out toxins' and 'make the body more alkaline'. Whether or not this is true is debatable.

If you make your juices with mostly vegetables, it may help, and it can keep the kilojoules down so your detox results in weight-loss. Otherwise, you're better off eating salads and raw vegies and getting the same result.

Can you overdo juice? Is it dangerous?

Seems unlikely. The only possible downside is too much potassium but that would only be a worry if you had a pre-existing heart or kidney complaint. Even then, it's hard to drink enough juice to send your potassium up to dangerous levels. Supplements added to juice are more of a worry.

What are the best juice combinations?

There's nothing magical about which fruit you put with which, despite all the hype. Most fruits team well with others and adding vegetables 'dilutes' the sugars and kilojoules of the fruit so they're not so concentrated. Try adding silver beet, carrot, spinach, parsley, celery, tomatoes or any other vegetable you like with fruit juice.

Here are some tried and tested combos you can make at home or order at a juice bar. Keep in mind that apple and carrot will work in just about anything and there's nothing like ginger for added zing.

• Orange, carrot and ginger
• Kiwifruit and carrot
• Apple, carrot, ginger and celery
• Carrot and grapefruit or orange
• Tomato, apple and parsley
• Watercress and pear
• Apple, beetroot and parsley
• Watermelon, celery and pineapple

Remember to focus on the amount of fruit you're adding and to keep your portions small.

My elderly mother has cancer and has been told to buy a juicer to make fresh juices. Will it really help?

It will if she needs to put on weight or doesn't feel like eating much.

Fruit juice is fruit that's been 'concentrated' – it's fruit in a form that's easy to get down. It packs in vitamins and minerals for an underweight person with a small appetite or someone recovering from chemotherapy. For these people, juice is a happy alternative to eating solid food.

How long can I keep juice that's been freshly-squeezed in the fridge?

Ideally drink it within an hour or two or it starts to become oxidised. If you want to make juice in advance, freeze it in half-cup portions and drink straight away once it thaws. Or add some lemon or lime to the fruit to slow down the oxidisation.

When Choice magazine tested juices (November 2007), it found that the juice from screw-press machines kept longer than those from centrifugal machines, which cut the fruit and expose it to the air.

What's the best type of juicer to buy for home use?

There are two types of juicers. Centrifugal or slow-turning (screw) models are more common and less costly. They have rotating blades which cut the fruit at high speed and 'push' it against a strainer. Non-centrifugal machines have a slow-turning screw which crushes the fruit. You get both pulp and juice so it's probably the next best thing to whole fruit. They can also juice wheatgrass or other fibrous greens.

For this reason, non-centrifugal juicers preserve more nutrients. In fact, Choice magazine (November 2007) found that non-centrifugal juicers extract as much as three times as many nutrients as juice extracted from centrifugal juicers.

Of course, if you only want to juice oranges or grapefruit, a simple citrus squeezer from the supermarket or a homewares store is all you need.

Are these juice add-ins beneficial?

• Wheat grass: Adds the same nutrients as parsley, spinach or other green leafy vegetables.
• Echinacea: Claimed to improve immune response and fight off colds. Only take it for short periods; for example, during winter.
• Ginseng: Said to give the body an overall boost and build stamina. But you'd be better off taking a ginseng supplement from a Chinese herbalist than getting some in your juice.
• Guarana: A form of caffeine from a vine native to South America - nothing special about it.
• Ginger: Adds heat and teams well with all fruit. Mild anti-inflammatory and may help overcome motion sickness or nausea.

Juice facts and figures