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A woman looks into a cup of coffee. Recent research underlines the health benefits of coffee and tea. But how much is too much? (Frank Gunn/Canadian Press)

Coffee has long been considered a beverage that provides a pleasant pick-me-up when sipped in moderation. Too much, however, and you might find yourself irritable, nauseous, twitchy — or, in worst-case scenarios, suffering from an irregular heartbeat, breathing difficulties and convulsions. Researchers have also examined the possibility caffeine may cause health problems related to cholesterol, bones and cancers.

Fear not, coffee aficionados: recent studies suggest the beverage may offer a host of health benefits. Doctors are not yet recommending people increase their daily doses and Health Canada continues to recommend moderation — not exceeding a maximum of about three eight-ounce (237-millilitre) cups of brewed coffee for healthy adults. But some researchers say new evidence shows coffee's potent antioxidants can prevent the onset of some diseases. Here's a roundup of the latest scientific research.

3 cups a day curbs memory loss?

Women aged 65 and older who drink at least three cups of coffee or tea a day are less likely to suffer memory loss, according to a French study published in the August 2007 issue of the journal Neurology.

Lead researcher Karen Ritchie, of the French National Institute for Health and Medical Research, said it was premature to suggest caffeine conclusively cut cognitive decline but she noted the psychostimulant appeared to have a positive effect on the brain.

The study also found the positive effects of coffee appeared to heighten with age. Women over 80 who drank three or more cups of coffee daily were found to be 70 per cent less likely to experience memory loss over those who didn't drink coffee.

Ritchie and her team observed the caffeine intake and cognitive skills of 7,000 participants over the course of four years.

A cup of coffee, a morning run help keep skin cancer at bay, researchers say

For many people, a morning cup of coffee followed by a workout is already part of their morning schedule. The good news, according to a U.S. study published in July 2007, is that this routine may help fight skin cancer. Researchers at New Jersey's Rutgers University said their study on hairless mice found that caffeine and exercise combined appear to kill precancerous cells that have been damaged by the sun's UVB rays.

Study author Allan Conney noted the results need to be quantified in humans but said that some researchers speculate exercise and caffeine can decrease tissue fat, thereby reducing the risk of cancer.

4+ cups of coffee daily cuts the risk of gout in men over 40

About one in 30 Canadians suffer from gout, a painful arthritic condition triggered by an excess of uric acid in the joints. People diagnosed with gout — a condition without a cure — often struggle with swollen toes, ankles, feet, hands and wrists.

But new research suggests people who have not yet suffered from gout may cut the risk of developing it by consuming large amounts of coffee. Men who drink six or more cups of coffee a day are 59 per cent less likely to develop gout over those who never drink coffee, according to a study published in the June 2007 issue of Arthritis & Rheumatism.

The study, conducted, by Canadian and American researchers, also said the risk was reduced by 40 per cent in men who drank between four and five cups of coffee daily.

While researchers were unable to definitively explain why coffee curbed gout, they noted that a strong antioxidant — phenol chlorogenic acid — may in part be responsible.

The study's authors also noted that it was too early for men to immediately bump up their coffee intake. The 12-year study included 45,869 men with no history of gout.

Coffee intake tied to lower diabetes risk

Women who incorporate at least six cups of coffee into their daily diets are less likely to develop Type 2 diabetes, according to University of Minnesota researchers.

The 11-year study, published in the June 2006 Archives of Internal Medicine, found that women who drank more than six cups of coffee a day were 22 per cent less likely than those who didn't drink any coffee to be diagnosed with diabetes.

Among people who drank six or more cups of decaffeinated coffee daily, the risk was lowered by 33 per cent.

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Some flavoured coffees can be loaded with as many calories as a healthy meal. ((Larry Crowe/Associated Press))

Researchers said minerals and nutrients in the coffee bean may aid with the processing of carbohydrates. The beans' antioxidants may also help protect cells in the pancreas, where insulin is produced.

The study included 28,812 post-menopausal women in Iowa starting in 1986.

A study published in the Archives of Internal Medicine  in December 2009 found that the consumption coffee and tea was associated with a lower diabetes risk among all adults.

The study was an analysis of previous studies on the topic. Among its conclusions were that each additional cup of coffee consumed in a day was associated with a seven per cent reduction in the excess risk of diabetes. People who drank three to four cups a day had a 25 per cent lower risk than those who drank between zero and two cups a day.

In addition, the study found that people who drank more than three to four cups of decaffeinated coffee a day had about a one-third lower risk of developing type 2 diabetes than those who drank none. Those who drank more than three to four cups of tea had a one-fifth lower risk than those who drank no tea.

Antioxidants lower risk of cardiovascular disease in women over 55

Potent antioxidants in coffee can help curb inflammation and lower the risk of cardiovascular disease in women, according to a 2006 U.S. study.

Researchers from the University of Oslo and the University of Minnesota followed more than 41,000 post-menopausal women between the ages of 55 and 69.

They found that including coffee in a diet appeared to help inhibit inflammation, thereby lowering risks of cardiovascular and inflammatory diseases, including arthritis.

The authors said a daily intake of between one and three coffees confirmed that the beverage offered a protective advantage.

The study was published in the May 2006 issue of the American Journal of Clinical Nutrition.

Coffee drinks loaded with fat, calories, advocacy group says

Consumers ought to think twice before they opt for specialty coffees, the U.S. Center for Science in the Public Interest said in a survey of Canadian coffee shops.

The survey found that a Tim Horton's double-double — a coffee with two creams and two sugars — contained 160 calories per 10-ounce cup (about 300 millilitres). By comparison, a black coffee had 10 calories and no fat. Nutritionists said that a drink such as Starbucks' blackberry green tea Frappuccino, which contains 560 calories and nine grams of fat in a 16-ounce (475-millilitre) serving, would have as much calories and fat as a healthy dinner of chicken breast, rice and vegetables.

Coffee overdose can lead to vomiting, diarrhea

These recent studies suggest those hooked on the bean needn't shun caffeine. However, before guzzling a pot, you may want to consider the many possible side-effects that Health Canada warns could result from a coffee overdose.

In people with sensitivities to caffeine, overdosing can lead to:

  • Insomnia.
  • Muscle tremors.
  • Nausea. 
  • Irritability.
  • Higher risk of bone fractures.
  • Mood swings.
  • Sleep disturbances.

In more serious cases, overdosing symptoms include:

  • Nausea.
  • Irregular heartbeat.
  • Diarrhea.
  • Vomiting.
  • Light flashes.
  • Breathing difficulties.
  • Convulsions.

Tea: Good health in a cup?

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The health benefits of tea are as varied as the types of the beverage, according to a series of studies. ((iStock photo))

Every year, Canadians steep, stir and sip seven billion cups of tea, according to the Tea Association of Canada. Many consumers consider tea to be a healthier alternative to coffee, offering a modest dose of caffeine compared to coffee's considerable jolt. In addition, green, black, white and oolong teas — all of which are harvested from the leaves and buds of the camellia sinensis plant — are rich in antioxidants and are believed to offer a host of health benefits, from soothing stress to regulating hormones.

Officially, Health Canada has sanctioned only the following three health claims: tea is a source of antioxidants, drinking tea can increase alertness, and tea may help maintain or support cardiovascular health. Still, many researchers continue to study tea's effects on the body, exploring the beverage's potential to boost health and block disease. Here's a roundup of the latest tea research.

Green tea capsules might help cure cancer: study

Concentrated amounts of green tea can help fortify the body's metabolic defence against cancer-causing toxins, according to an August 2007 study. The study, published in Cancer Epidemiology, Biomarkers & Prevention, is the latest in a growing body of research touting green tea's cancer-fighting properties. The study, led by researcher H.H. Sherry Crow of the Arizona Cancer Center, was conducted on 42 volunteers.

Participants in the study were given capsules containing 800 milligrams of a compound called epigallocatechin gallate (EGCG), which is found in green tea. Researchers found the EGCG pills helped increase production of detoxification enzymes by as much as 80 per cent.

Chow cautioned the results weren't immediately cause to bump up green tea consumption, saying more research in the field is needed.

Green tea baths might help ease dandruff, psoriasis

Mice bathed in green tea extracts developed smaller, less inflamed lesions associated with psoriasis, according to researchers at the Medical College of Georgia. In the study published in the August 2007 issue of Experimental Dermatology, lead researcher Dr. Stephen Hsu said green tea appeared to slow the production of skin cells.

Mice bathed in warm water also developed larger skin lesions earlier than mice bathed in green tea extract, the study said. Hsu is looking to extend the study's applications to humans but notes that chemicals in green tea oxidize very quickly when added to other ingredients. He said researchers are aiming to create a formula that will be able to permeate skin.

Green tea might help ease rheumatoid arthritis

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Preliminary findings from a new study suggest that green tea could help relieve swelling and pain for rheumatoid arthritis sufferers.

University of Michigan researcher Salah-uddin Ahmed presented the research in April 2007 at the Experimental Biology meeting in Washington, D.C. Ahmed's team took cells from the joints of arthritis patients and exposed them to an active ingredient in green tea called epigallocatechin gallate (EGCG).

The cells were then stimulated with a protein that causes joint degradation. The study found the treated cells were better able to block the protein's harmful enzymes than untreated cells.

Ahmed noted the research was still in its early stages and was not yet cause for arthritis sufferers to drink tea as a treatment. Still, he noted, incorporating green tea into the diet probably would offer other health benefits.

Two cups of spearmint tea normalize hormone levels

Waxing, plucking and shaving are some of the ways many women get rid of unwanted hair on their faces, breasts, and stomachs, but new research suggests two cups of spearmint tea might be a good natural alternative.

A Turkish study published in the February 2007 issue of Phytotherapy Research shows that drinking two cups of spearmint tea a day for five days can help bring down levels of "masculinising" androgen hormones in women.

Lead researcher Mehmet Numan Tamer studied 21 women with excessive hair growth. Participants were given herbal tea made with one cup of boiling water and one teaspoon of dried leaves, steeped for five to 10 minutes. Blood tests later indicated androgen levels had dropped.

This study builds on other research that suggests spearmint extracts lower libido in men and androgen levels in rats.

Hold the milk for best heart-healthy benefits, researchers say

Thanks to a growing body of research, tea drinkers tout the soothing and heart-healthy qualities of tea. But in January 2007, researchers cautioned that adding a splash of milk to the brew might blunt its many benefits. In a German study published in the European Heart Journal, researchers said tests on volunteers found that while black tea helped arteries relax and expand, the addition of milk inhibited the effect.

Researchers observed 16 healthy post-menopausal women for the study. The participants were given half a litre of black tea, black tea with 10 per cent cream, or boiled water on three separate occasions.

Study author Dr. Verena Stragl, a professor of cardiology at the University of Berlin, said a milk protein reduces the amount of catechin compounds in tea, which protect against heart disease. Stragl said her research team would subsequently study the effects of green and black tea on the cardiovascular system.

Tea soothes stress, study says

Find yourself turning to a cup of tea in troubled times? According to researchers at University College London, people who drink tea are better able to recover from stress. In a study published in the October 2006 issue of Psychopharmacology, researchers found that men who drank black tea four times daily over a six-week period had lower levels of a stress hormone called cortisol in their blood compared to men given a placebo tea.

The study participants were 75 male tea drinkers, who were put in stressful situations while researchers monitored their levels of cortisol, blood pressure and heart rate and asked them to describe their stress levels. Less than an hour after the task, cortisol levels fell an average of 47 per cent in tea drinkers, compared to a 27 per cent drop in the placebo group. Researchers said they were unable to pinpoint which ingredients in tea aid in regulating cortisol levels.