Drinks compared

Water

Water is kilojoule-free, fat-free, and sugar-free. So it should be your main beverage choice. A simple check to see if you're drinking enough is to check the colour of your urine. It should be yellow first thing in the morning but paler by mid-morning. If it isn't, you're not drinking enough.

There's also evidence that drinking reticulated (local-authority supplied) water that contains fluoride can help prevent tooth decay.

Milk

Milk is an important source of calcium, protein, potassium, and vitamin D. A low calcium intake is linked to an increased risk of osteoporosis.

Full-fat milk contains more energy, fat and saturated fat. So everyone over the age of two should drink low-fat or reduced-fat milk. If you can't drink milk, soy products are an alternative - but make sure you choose a calcium-fortified variety.

Flavoured milk is okay for an occasional treat. But break it down (by half) with trim milk, to keep the sugar and kilojoules under control.

Tea and coffee

Tea and coffee don't provide a lot of nutrients. But if you don't add lots of sugar and milk, they don't have many kilojoules either. Steer clear of the super-sized creamy and sweetened drinks - they can be a waistline killer! In some of these drinks there's more kilojoules than in a Big Mac with a medium Coke. Always choose the smallest serve available.

Caffeine is a stimulant that works by muscling-in on spaces in your brain normally reserved for the natural sedative adenosine, so that your body gets told to get going instead of slowing down. The effects of caffeine vary from person to person depending on age, body size, and general health.

The upside is that a small amount of caffeine improves your mental and physical performance, your reaction time, and even your mood. Population studies suggest that coffee drinkers have a lower risk of diabetes and Parkinson's disease.

There's no strong evidence that moderate caffeine is associated with adverse health effects. But too much can cause anxiety, restlessness, irritability, sleeplessness, headaches, stomach upsets, and nausea. Very high intakes are linked with osteoporosis, high blood pressure, and raised cholesterol levels.

About four or five average-strength cups of coffee or their equivalent is okay for most adults - that's about 300mg. Pregnant women, children and people sensitive to caffeine should limit their intake. Cola soft drinks, energy drinks and chocolate also contribute to your caffeine intake.

Tea and coffee also contain antioxidants, which may protect against cancer and heart disease. Green tea contains more than black tea - but most herbal teas don't count, as they don't contain real tea.

The tannins in tea and coffee reduce iron absorption so don't drink them with meals.

Fruit juice

Pure fruit juice can contribute to just one of your five-plus servings per day of fruit and vegetables. It provides vitamins and minerals - and some fibre, but not as much as whole fruit. Whole fruit is also more filling.

It's important to remember that pure juices have around the same amount of energy and sugar as soft drinks. So they have the same potential for weight gain and tooth decay.

Diet drinks

Diet soft drinks use artificial sweeteners instead of sugar. They provide the sweetness without the kilojoules. So far there's limited research that looks directly at diet soft drinks and their effect on health, but health professionals have some concerns.

Diet drinks may create a preference for sweet foods. This is especially a problem for children, as it may lead to unhealthy food choices later in life. And diet soft drinks may displace milk in the diet - a particular concern for adolescents. The caffeine in some diet drinks also increases urinary excretion of calcium, which is not good for building healthy bones and teeth.

Of most concern is the effect on tooth decay. Although they're sugar-free, diet soft drinks have a low pH - which may erode tooth enamel.

All artificial sweeteners permitted in the food code are regarded as safe. But people with the rare condition phenylketonuria should avoid aspartame. For this reason, all products containing aspartame have a warning label.

Sports and flavoured waters

Sports waters contain only small amounts of sugar or none at all, which means they're a good alternative to soft drinks when consumed in small quantities. But they're still acidic and so may cause tooth decay. The added vitamins and minerals won't do you any harm, but are unlikely to offer any benefit that you wouldn't get from a healthy diet.

Make sure you read the fine print. H2Go Sparkling Cranberry Flavoured Water contains about six teaspoons of sugar and more than 400 kilojoules in a serving.

Sports drinks

Sports drinks have fewer kilojoules than soft drinks. But they don't provide any real benefit, unless you're an athlete who trains for longer than 90 minutes. They provide a short-term sugar "kick" and electrolytes to assist hydration. For most people, water's a better option.

Alcohol

Studies show that moderate drinkers (one to two drinks a day) have healthier hearts and live longer than heavy drinkers or teetotallers. The antioxidants in red wine were thought to make the difference, but now it seems a moderate amount of any alcohol will do the trick. The benefits are limited to a couple of standard drinks a day, and mostly for middle-aged and older men and post-menopausal women.

Excessive alcohol intake causes serious health and social problems such as heart disease, some cancers, liver disease, domestic violence and traffic accidents. And it's double-trouble for your waistline - it has "empty" kilojoules and it increases your appetite.

Men should have no more than three standard drinks a day and women no more than two. A standard drink is less than you might regularly pour - you should get 71/2 standard glasses of wine in one bottle. It's also a good idea to have a couple of alcohol-free days a week.

Children and pregnant or breastfeeding women should avoid alcohol.

Soft drinks, fruit drinks, energy drinks

Soft drinks have no benefits. They may cause tooth decay, they produce unwanted kilojoules, and they include little or no nutrients. One can of soft drink contains about 10 teaspoons of sugar - you wouldn't stir that into a cup of tea or coffee, would you? The same goes for high-sugar fruit drinks such as cordials.

In 2005 a scientific committee of the Agencies for Nutrition Action published a report reviewing research into the association between high-sugar drinks and children's weight gain. Eleven of the 16 studies found that consuming sugary drinks increased the risk of obesity, five found no association. This suggests we should limit our intake of these drinks.

Energy drinks are no better - and they contain caffeine. About the same amount of caffeine in a strong cup of coffee would stir your kids up.

All these drinks may also displace healthier options in the diet, like milk and water.

Report by Belinda Allan.