A woman tastes one of southern Italy's full-bodied red wines, near Guagnano, in Puglia, the heel of boot-shaped Italy. Red wine has been touted as beneficial to cardiovascular health, but new research suggests that drinking more than a certain amount of that favourite Merlot or Shiraz may actually be harmful over time. (Pier Paolo Cito/Associated Press)

It's been quite a decade for wine sales in Canada. In 2007, Canadians spent $5 billion on wine — an increase of 9.5 per cent from the year before, according to figures from Statistics Canada.

Canada's love affair with fermented grape juice really began taking off in the late 1990s, when wine accounted for 21 per cent of sales of all alcoholic beverages across the country. Since then, market share for beer and spirits has been declining while wine's popularity has been increasing. It now accounts for 28 per cent of the alcoholic beverage market.

Most of that growth has been due to a surge in red wine sales. Since 2000, sales of red wine are up by 130 per cent compared to a 33 per cent increase for white wine. Sales of red outpace sales of white in every province except New Brunswick and Prince Edward Island.

The wine tide appears to have turned in the late 1990s when research about red wine's potential health benefits began to surface.

The benefits of red wine appear to be linked to the presence of resveratrol, melatonin and flavonoids.

Flavonoids are thought to help protect the body from cancer because of their antioxidant properties. They help the body neutralize certain free radicals that can trigger the cellular activity that may lead to cancer.

Melatonin — a substance present in red wine and some foods and that humans naturally produce in small amounts — is thought to delay the oxidative damage and inflammatory processes typical of old age.

Resveratrol is produced naturally by grape skins during red wine's fermentation process. Several studies have suggested that resveratrol may explain the "French paradox" — why the French appear to be able to consume a diet higher in fat than the norm while enjoying a comparatively lower incidence of heart disease.

High doses of the chemical appear to mimic the effects that a 20 to 30 per cent reduction in calories in the typical diet would have. Researchers say such a diet is effective at prolonging life in many species.

A study released in June 2008 found that not only is resveratrol effective at protecting the heart at high doses, but it can also be effective at low doses beginning in middle age, leading to a healthier heart and better quality of life in old age.

Red wine has been credited with more than keeping your heart healthy and delaying the aging process. It has also shown promising results in preventing prostate cancer, diabetes, Alzheimer's disease, leukemia and some common food-borne illnesses.

Not all effects are positive

But the long list of potential health benefits does not necessarily mean red wine should be a staple in every household.

Wine is an alcoholic beverage, and pregnant women — or women contemplating having a baby — should avoid alcohol. It can be dangerous to the fetus.

Alcohol can also increase a woman's risk of developing breast cancer. Two drinks a day can increase a healthy woman's risk by 10 per cent — or more if there is a family history of the disease.

Red wine can also trigger migraines in people who are susceptible to them, probably because of the accumulation of histamines and tannins from prolonged contact with the skin of the grape during the fermentation process.

Wine can also elevate your triglyceride levels. High triglyceride levels are associated with health problems such as diabetes.

Drinking wine — or any other alcoholic beverage — can also lead to weight gain. A glass of wine contains about 120 calories and no nutrients — that is, empty calories. Get together with friends, have a few glasses of wine along with a small plate of hors d'oeuvres, and you're approaching your total recommended caloric intake for the entire day. If you're not active, before long, your waistline will be in expansion mode.

Worldwide, drinking causes almost as much harm as smoking, according to the World Health Organization. The agency estimates that alcohol causes 1.8 million deaths around the world every year; about a third of those deaths are accidents that could have been avoided.

The WHO also estimates that worldwide, alcohol causes or plays a role in 20 per cent to 30 per cent of all cases of esophageal cancer, liver cancer, cirrhosis of the liver, homicide, epileptic seizures and traffic accidents.

Even in France, attempts have been made to make the country more aware of the potential pitfalls of alcohol. A 2005 report urged the French government to snap out of its state of national denial and take urgent steps to address the problems of alcohol abuse. The report found that alcohol was directly responsible for 23,000 deaths a year in France and indirectly responsible for 22,000 more.

The report's author, Hervé Chabalier, said one person in 10 in the country is ill because of the effects of alcohol.