Health Benefits of Green Tea

Green tea
Green Tea

Tea is the most widely consumed beverage in the world, second only to water.  There are three main types of tea, green, black, and oolong.  Scientific studies suggest that green tea in particular has many health benefits.  Researchers believe the antioxidants, which are mostly polyphenols, in the tea leaves are responsible for the health benefits.

Green, black, and oolong teas are all derived from the leaves of the Camellia synensis plant.  This plant grows throughout Asia, parts of the Middle East, and Africa.  Green tea is prepared from unfermented leaves.  The leaves of oolong tea are partially fermented, and the leaves of black tea are fully fermented.  The more the leaves are fermented, the lower the polyphenol content and the higher the caffeine content.  Green tea has the highest polyphenol content, while black tea has 2 to 3 times the caffeine content of green tea.  Therefore green teas have the most nutritional benefits, followed by oolong and black teas.  You may have heard of white tea, which is simply the unfermented young leaves and buds of the Camellia synensis plant.

Reasons to Drink Green Tea

The health benefits of drinking green tea:

  1. Green tea is rich in antioxidants: The antioxidants found in green tea are mainly polyphenols.  A particular polyphenol, EGCG has been studied extensively, can powerfully destroy free radicals (metabolic byproducts that are chemically reactive and that can damage cells).  In research published in the European Journal of Clinical Nutrition, the polyphenols found in green tea are reported to be 6 times stronger than those found in black tea.
  2. Green tea lowers LDL (bad) cholesterol:  Research shows that green tea lowers LDL (bad) cholesterol and raises HDL (good) cholesterol in people.  One large-scale study found that men who drink green tea have lower total cholesterol than those who do not drink green tea.
  3. Green tea fights atherosclerosis: Large scale studies suggest the polyphenols in green tea help prevent atherosclerosis, the plaque buildup in your arteries.  The researchers believe that green tea fights atherosclerosis by lowering cholesterol and triglycerides.  Studies show that black tea has similar effects.  In fact they  estimate the rate of heart attacks decrease by 11 percent with consumption of three cups of tea daily.
  4. Green tea lowers risk of high blood pressure: A study published in 2004 reported that regular consumption of green and oolong tea reduced risk of developing hypertension.  Another study published in 2012 reported that regular long-term consumption of black tea lowered blood pressure.
  5. Green tea lowers cardiovascular disease risk: In a large-scale study, drinking three cups of green tea or black tea is associated with a 20 percent reduction in stroke risk.
  6. Green tea lowers cancer risk: Risk of cancer of the GI tract has been shown to be 17 percent lower in women who drink at least 3 cups of green tea a week.  There have also been lower risks associated with green tea consumption of the following cancers:  bladder, breast, ovarian, lung, pancreatic, prostate, and skin.
  7. Green tea strengthens your bones: The Harvard School of Public Health states that the tea polyphenols are thought to strengthen bones and protect against fractures.  Also a study published in Nutrition Research found the bioactive components of green tea may help decrease the risk of fractures by improving bone mineral density.
  8. Green tea helps protect your vision: A 2010 study reported that the components in green tea positively affected the tissues of the eyes, particularly the tissues of the retina.
  9. Green tea improves memory and cognitive function: Some of the compounds found in green tea boost certain brain tasks associated with working memory.  Working memory is the brain function that keeps in mind and manipulates multiple pieces of information simultaneously, helping you to plan ahead, organize information, solve problems and retrieve information, such as names.
  10. Green tea calms and relaxes you: L-theanine is the standout ingredient in green tea that has been studied for its calming effects on the nervous system.  A study published in Trends in Food Science & Technology found that green tea produces relaxing effects without drowsiness after just 40 minutes of ingestion.

Putting it into Practice

  • Brew it yourself: For the biggest benefit, definitely brew it yourself.  Bottled tea has significantly fewer polyphenols than home-steeped tea, plus added sugar that add unwanted calories.  You can serve it hot, or make a pitcher of home-brewed iced tea during the warmer months.
  • Watch the additives: It is not a good idea to resort to additives to make tea more palatable.  Be careful not to add spoonfuls of sugar to make tea go down easier.  The health benefits were observed for tea with little or no additives.  So maybe try a little honey or lemon to taste without compromising the purity of your tea, but stop there.
  • Daily dosage: The University of Maryland Medical Center recommends two to three cups of green tea per day.  This provides about 240 to 320 mg of polyphenols.
  • Try a healthy alternative: If you just can’t stomach green tea, you may want to try a healthy alternative – coffee.  Coffee is a perfectly reasonable and possibly equally healthful alternative.  Click here to read my article on coffee.
  • Caution if you are pregnant: Because of its caffeine level, green tea can be unsafe for pregnant women and their babies.  Always consult your doctor about consuming caffeinated beverages while pregnant.
  • Problem with iron: Drinking green tea may cause your body to absorb less iron, so it is best not to drink green tea with an iron-rich meal.  Rather drink green tea between meals.  Consult your doctor if you are anemic.

Spotlight on Coffee

Coffee beans closeup
Coffee beans closeup

We used to hear that coffee was a guilty pleasure at best and a health evil at worst.  However researchers at the Harvard School of Public Health have found that coffee can be good for you.  Their research findings show that people who drink moderate amounts of coffee daily are less likely to die from a range of diseases, from diabetes to heart disease.   They found that both caffeinated and decaffeinated coffee helped.  Their main message is that regular consumption, about three to five cups a day, is associated with lower total mortality (premature death) and mortality from several causes, like diabetes, cardiovascular disease and suicide.

The Scientific Studies

The Harvard School of Public Health looked at surveys of more than 200,000 doctors and nurses who regularly updated researchers on their eating and other lifestyle habits and details about their health for about 30 years.  They found that coffee drinkers were less likely to die over the decades than non-drinkers.   The effects were even stronger for non-smokers who drank coffee.  It turned out that non-smokers who regularly drank three to five cups of coffee a day had a 15 percent lower risk of mortality.  The researchers caution that people should be aware of the amount of added sugar to coffee drinks which can be a problem.  They also point out that a cup is a small 8-ounce cup of black, or almost black coffee.  Not a 32-ounce mocha frappuccino.

The researchers also looked beyond total mortality and looked at specific causes of death.  They found that people who drink moderate amounts of coffee daily have lower risk of death from cardiovascular disease, diabetes, neurological disease (such as Parkinson’s) and suicide.  It is important to note that the study does not prove cause and effect between drinking coffee and living longer.  Rather, it points to an association.

Coffee is the number one source of antioxidants in the American diet, and the researchers think that the antioxidants work together to provide some of the health benefits.  They also conclude that since the benefits are seen in both regular and decaf coffee, that points to caffeine not being responsible for the benefits.  The researchers are not advocating coffee as a strategy for prevention of chronic diseases because other factors in the diet have a bigger effect.  The main message is that people who enjoy drinking coffee should not worry that it may be harmful to their health.  Coffee may actually be beneficial to their health when consumed in moderate amounts.

The findings were published in November, 2015 in the journal Circulation.

The Health Benefits

Moderate consumption of coffee:

  1. Helps you live longer.
  2. Lowers risk of depression.
  3. Lowers risk of type 2 diabetes.
  4. Lowers risk of cardiovascular disease.
  5. Lowers risk of neurological diseases like Parkinson’s disease.
  6. Lowers risk of suicide.

Does Coffee Raise Blood Pressure?

According to the researchers at Harvard’s School of Public Health, people who are not used to caffeine will experience a substantial increase in blood pressure when they start consuming caffeinated beverages like coffee.  However within a week of caffeine consumption, that effect is less pronounced.  After several weeks of continued caffeine consumption, however, a small increase in blood pressure remains.  They suggest that people who have hypertension switch from caffeinated coffee to decaffeinated coffee, to see if it has a beneficial effect.

Does Coffee Raise Cholesterol?

Turns out that people who have high cholesterol should watch how they prepare their coffee.  Coffee contains a substance called cafestol which is a potent stimulator of LDL (bad) cholesterol levels.  Cafestol is found in the oily part of coffee, which is present whether or not the coffee is decaffeinated.  When you brew coffee with a paper filter, the cafestol gets left behind in the filter.  Other methods of coffee preparation, such as the boiled coffee common in Scandinavian countries, French press coffee, or Turkish coffee, are much higher in cafestol.  So for people who have high cholesterol levels or who want to prevent having high cholesterol levels, it is better to choose paper filtered coffee or instant coffee, since they have much lower levels of cafestol than boiled or French pressed coffee.  Espresso is somewhere in the middle;  It has less cafestol than boiled or French pressed coffee, but more than paper filtered coffee.

Putting It Into Practice

  • Moderate consumption: Three to five cups a day seems to be the coffee intake where benefits were seen.  The benefits diminish for intakes lower than two cups a day and above six cups a day.  A cup is 8-ounces.
  • Watch the caffeine: Keep caffeine intake to less than 400 mg per day especially if you are sensitive to it.  Research has shown that consuming more than 400 mg of caffeine can interfere with sleep and create feelings of unease.  You can try decaf or half regular/half decaf coffee if you are sensitive to caffeine.  Pregnant women should also watch their caffeine intake and consult their doctor.
  • Don’t smoke: The studies found that coffee consumption did not offset the damages caused by smoking.
  • Go with paper filtered coffee: If you have high cholesterol or are watching your cholesterol levels, you may want to lower your consumption of boiled coffee beverages.
  • Go with black, or almost black: Watch what you add to coffee.  Heavy cream, caramel, sugar, and syrups all add calories to your coffee, and could increase cholesterol levels if you consume these items regularly.