Wine: Drink to your health?

We give you the lowdown on wine – is it beneficial, harmful, or both?

We've been drinking wine for thousands of years, possibly since around 6000BC. Our first wines were probably discovered by accident as grapes spoiled and fermented in a container. One Persian fable claims wine was discovered by a Princess who tried to poison herself by eating grapes that had spoiled in a jar, but instead she fell asleep to awaken later feeling relieved of her stresses.

Up until as late as the 18th century, wine was considered safer to drink than water, as most harmful microorganisms are inhibited or killed off by the acids and alcohols in the wine. Which may be why Jesus is said to have turned water into wine. These days water is usually safe but there are many other reasons why people drink wine.

What's in wine?

Grapes

Wine is (usually) made from grapes, which are crushed to separate the juice from the skins and stems. The juice is fermented with yeast, which turns most of the sugars to alcohol. Different types of wine are fermented differently; oak barrels can be used to impart flavour and wines are aged for months and years.

Additives

You may see 'contains sulphites' on wine labels. Sulphur dioxide is a natural product of fermentation, and is also often added to wine for its preservative and antioxidant properties. Other preservatives which may be used include potassium sorbate and ascorbic acid (also known as vitamin C). You will sometimes see 'contains traces of egg, dairy or fish products' on wine labels, which may seem a little odd. These ingredients are used as 'fining agents' to clarify and filter wine, and tiny traces can remain in the finished product. You won't taste them – in fact they can barely be detected using scientific instruments – but legally winemakers must declare their use on labels as they are potential allergens.

Nutrients

Nutritionists often refer to alcoholic drinks, including wine, as 'empty kilojoules' because they are high in energy without providing other nutrients. A 100ml glass of wine provides around 360kJ of energy, most of it from the alcohol. Wine has little of the macronutrients – carbohydrate, protein and fat – and only trace amounts of the micronutrients – vitamins and minerals. But it does contain differing levels of antioxidants and this is where some of the purported health benefits come from.

Kilojoules

When watching your weight you may be careful about what you eat, but it's easy to forget that what you're drinking can also have a significant impact on your daily kilojoule intake. Compare the kilojoules in two (standard) glasses of wine with foods you consume. And, remember, you are not getting needed nutrients from an alcoholic drink.

Sugar

Some people believe that wine contains a lot of sugar but as we've said, it's the alcohol that's providing most of the energy in wine, not anything else. Most wine which is considered 'dry', that is with no sugar added after fermentation, contains only 1.5 to 3g of residual sugar (that's equal to about 1/3 to 2/3 of a teaspoon of sugar) per litre, so a standard glass of dry wine has virtually no sugar in it at all. Some winemakers in New Zealand add small amounts of sugar to improve the flavour of wine. A glass of medium or sparkling wine might contain the equivalent of 1/2 to 3/4 of a teaspoon of sugar. On the other hand a sweet wine like a dessert wine contains the equivalent of around 2 teaspoons of sugar in a 100ml glass.

A health drink?

'The French paradox' describes the low rate of heart disease in France despite a high-fat diet. Unlike the Mediterranean diet with lashings of olive oil (high in monounsaturated fat), the French diet is laden with saturated fats from full-fat dairy products. The French also drink a lot of wine, especially red wine. Kiwis drink around 12 litres of wine on average each year compared to over 50 litres for the French. (Keep in mind we have higher consumption of other alcoholic drinks.) This high consumption of wine has led to a great deal of research around its possible health benefits.

When making red wine the grape skins and seeds are included in the fermenting grape juice, which is why red wine seems to contain more antioxidants than white (the antioxidants are concentrated in the grape skins and seeds). Resveratrol is an antioxidant in red wine that some believe responsible for the French paradox.

Recent research from the US found that mice given a very high-fat diet and simultaneously treated with resveratrol lived longer and didn't suffer the health problems normally associated with obesity. When their livers were compared, the untreated mice had swollen livers filled with fatty deposits whereas the livers of the resveratrol-treated mice looked normal. Overall the resveratrol appeared to counteract any negative effects of the fatty diet; the obese mice were in rude health. Unfortunately there's a little more work to be done before any recommendations about wine drinking can be made: the amount of resveratrol given to the mice would be equivalent to 100 glasses of red wine a day for you or me!

Light or moderate drinking is known to be associated with a lower risk of heart disease for post-menopausal women and for men over 45 years old, and it's possible this heart-protective effect may extend to others. It's also thought that moderate wine consumption may lower the risk of developing Alzheimer's, although more research is needed.

A health trap?

Before you order that case of red 'for the good of your health', take a moment to consider the downsides of drinking wine. These are related to consumption higher than the guidelines.

So if you're a woman routinely drinking three (100ml!) glasses of wine a day (which for many of us, the way we pour our glasses of wine, is actually only one glass…) or a man drinking four, this is for you:

What does 'moderation' mean?

The 'standard drink' measures the amount of pure alcohol in a drink. One standard drink equals 10g of pure alcohol. The amount of alcohol in wine can vary and the standard drink is usually quoted as 100ml, but some sources prefer the more conservative 80ml. Essentially, a standard drink of wine is a small glass. Measure 80 or 100ml and pour it into your usual wine glass; hopefully you won't get a fright! (When I poured myself a glass of wine in one of my fashionably large wine glasses – half full – and then measured it, I found it was nearer 125ml. Ouch!) Another way to look at it: a 750ml bottle of wine is the equivalent of seven and a half to nine standard drinks.

The maximum number of standard drinks advised for responsible drinking

For women

• In one week: no more than 14
• If drinking every day: no more than 2
• In one session: no more than 4

For men

• In one week: no more than 21
• If drinking every day: no more than 3
• In one session: no more than 6

When not to drink

It's best not to drink at all if you're:

• pregnant or trying to become pregnant
• going to drive
• going to operate machinery
• on medication (take advice)

Why men can drink more

The different amounts for women and men are not solely based on differences in body weight: a man of the same weight as a woman can process alcohol more effectively than the woman can.

• In the stomach the enzyme which processes alcohol (alcohol dehydrogenase) is 70-80% more effective in men.
• Lean muscle has more blood supply than fat tissue. As women usually have a higher proportion on fat tissue than men, men have more blood for the alcohol to circulate in before it gets to the liver for final breakdown (so their blood: alcohol level will be lower).
• Men's livers can also process alcohol more quickly.

While drinking in moderation has positive health benefits, the long-term effects of drinking more than moderate amounts of any alcohol can be serious. It is a known risk factor for a number of cancers: oral, pharynx, oesophagus and larynx. It is also a probable risk factor for other cancers: stomach, colon, rectum, liver, breast and ovary.

The 'alcohol-free day'

In theory there is no reason why you shouldn't drink every day, as long as you are able to drink in moderation. If your habit is to have one glass of wine, or even two (so long as they're not 'buckets) with your dinner each night, you don't need to worry. But if one glass soon becomes three, regular alcohol-free days (AFDs) can be useful to keep the drinking in check.

There is a strong relationship between alcohol consumption and blood pressure. While an initial drink may lower blood pressure slightly, regular drinking beyond recommended levels can increase blood pressure: the more you drink, the higher it can get.

Over-indulgence of any alcohol will have immediate undesirable physical and mental affects. The social consequences of excessive drinking, whether a one-off or long-term, can be significant. So if you do drink, there are many good reasons to limit the amount. And if you don't drink, there's really no health reason to start.

Cheers!

New Zealand has a name for producing some outstanding wines and drinking wine can be part of socialising and winding down at the end of a day's work; the alcohol, initially at least, helps us to relax. The best way to enjoy wine is with food as this slows absorption of the alcohol. It's a good idea to drink water at the same time (or alternate them), so that you can savour the wine and quench your thirst with the water.