As you read the title of this blog, what beverage pops into your mind as the most widely consumed beverage in the world? Did you think of a soft drink; perhaps juice, milk or even coffee? If you guessed any of these, you would be incorrect.

how-does-tea-affect-diabetesAccording to the Tea Association of the USA, tea ranks first after water of all beverages consumed in the world.(1) With over 1500 varieties of tea available in the world(2) and 365 days in a year, it would take over four years to try them all.  Let us delve into some interesting questions about tea including special information about four studies suggesting tea consumption may help prevent diabetes and one study suggesting tea may promote diabetes.    

Question 1: What can growing tea be compared to?
Growing tea leaves can be compared to wine cultivation. The character of the tea is influenced by the geography of the land. Elevation, soil quality, wind conditions and growing temperature all influence the character of the tea.(2)  

Question 2: How common is tea in households in the United States?
In the United States tea is found in approximately 80 percent of households.(1) Approximately 85 percent of tea consumed in America is iced.(1)

Question 3: Where is tea grown in the world and what conditions are favorable for growth? 
Tea is grown in many places throughout the world. Top countries that produce tea include; China, India, Kenya, Sri Lanka, Turkey, Vietnam, Indonesia, Argentina and Japan.(3) It is surprising that tea also is grown in a few places within the United States. For information on tea grown in South Carolina, Hawaii, Alabama, Michigan, Oregon, and Washington State visit the World of Tea website.

In the world, tea plants grow well in tropical areas with high altitudes as well as subtropical lowland areas. The best temperatures to grow tea is between 65-86 degrees Fahrenheit. Growth will cease below 55 degrees Fahrenheit and above 95 degrees Fahrenheit.(5) The University of Florida has some good information on growing conditions for tea

Question 4: What is the scientific name for tea, what kind of tea comes from this plant and what are herbal teas?
Camellia sinensis is the scientific name for tea.(6) The leaves of the tea plant are brewed to make the beverage. The plant is an evergreen shrub which bares white flowers and is part of the Camellia family.  In the wild, this plant can form a small tree.(7)

All tea that is referred to as “true tea”, comes from the leaves of the same plant (Camellia sinensis).(8) True teas include, black tea, scented black, tea, oolong tea, green tea, white tea, yellow tea and art tea. Oregon State University provides information on how true tea is processed

Herbal teas do not come from the Camellia sinensis plant and are not true teas. These “teas” come from dried fruits and herbs and are infused with hot water. Examples of these “teas” are rooibos, chamomile, mint, sage, thyme and mate.(9) 

Question 5: Is there information available on growing tea?
Information to grow tea can be found at the College of Tropical Agriculture and Human Services, University of Hawaii at Manoa. 

Question 6: What is the best way to make and store tea?
According to the United Kingdom tea council, the best way to make tea depends on the type of tea one is using. Store tea at room temperature in an air-tight container.(10) Here you can find instructions on making the perfect cup of tea.  

Question 7: When drinking tea, should it be counted towards the amount of fluid one should consume?
According to the British Dietetic Association, tea can count toward your daily fluid intake. Drinking tea does not have a diuretic effect unless more than 300 mg of caffeine is consumed at one sitting.(11) According to the Mayo Clinic, the amounts of caffeine in 8 ounces (240 milliliters) of brewed tea are listed below:
  • Black Tea: 14-61 mg (12)
  • Decaffeinated Black Tea: 0-12 mg (12)
  • Green Tea: 24-40 mg (12)

The amount of caffeine in tea increases with brewing time.(13) For more information on caffeine in tea, visit Caffeine and Tea: Myth and Reality

Question 8: Are there any recent studies on the effects of drinking tea and diabetes?  
Below you will find results of recent studies on diabetes and tea.
  • In 2012 the British Medical Journal (BMJ) released a study investigating statistical relationships between the consumption of black tea and key health indicators in the world.  The authors found a correlation between high black tea consumption and the incidence of low diabetes prevalence in the world.(14) 
  • A Chinese study published in 2013 concluded that drinking 16-30 cups of green or rock tea (a type of oolong tea) may protect against the development of type 2 diabetes.(15) 
  • An overview written by the University of Maryland, states that in animal studies green tea may help prevent the development of type 1 diabetes and slow its progression once it develops. In people, green tea may help with glucose regulation.(16) 
  • A small 2011 study that took place in Basrah Iraq, investigated the incidence of type 1 diabetes in children who were exposed to tea prenatally. Subjects included 96 children with type 1 diabetes and 299 children without diabetes. Researchers concluded that tea drinking during pregnancy may trigger the immune system leading to the destruction of beta cells and the development of type 1 diabetes in children.(17) 
  • In 2012 the Tea Consumption and Incidence of Type 2 Diabetes in Europe Study which is known as: The EPIC-InterAct Case-Cohort Study was published. The research took place in 26 centers in 8 European countries with thousands of participants. The researchers concluded that individuals who drink at least 4 cups of tea per day may have a 16 percent lower risk of developing type 2 diabetes than non-tea drinkers.(18) 
As you can see, tea is a very popular beverage throughout the world. If you enjoy drinking tea and have diabetes, ask your medical team if it is safe for you and how many cups you may have a day.