Black Tea May Lower Type 2 Diabetes Risk
Given the current epidemic of type 2 diabetes around the world and the less than optimistic estimates of its rising prevalence, it's important for people to know about all the ways they can help reduce their chance of developing the disease. A new study indicates that making black tea a part of your routine may lower the risk of type 2 diabetes.
Black tea is good for diabetes
Tea--red, white, oolong, and black--is the most popular flavored beverage in the world, and its health benefits have been the subject of countless studies. The reason why tea offers so many advantages in the fight against cancer, heart disease, obesity, inflammation, and type 2 diabetes has been credited to the presence of plant substances called polyphenols.
Before discussing the new study on black tea and diabetes, it's worth mentioning that another new article was just published on a chemical analysis of black tea. The Rutgers University study emphasized that black tea polyphenols, which include the simple catechins theaflavins and thearubigins along with others, are among the reasons why black tea has "preventive and therapeutic properties in human diseases such as cancer, and metabolic and cardiovascular diseases, etc."
The Rutgers study also noted that pointed out that the positive results of research on tea have led to the development of more than your typical tea bag, with products including tea-based functional beverages, tea concentrates, foods containing tea, and dietary supplements. These options allow people to reap the health benefits of tea in a variety of ways.
In the new study, published in BMJ Open, the researchers analyzed data regarding consumption of black tea from 50 different countries based on 2009 sales figures. They also evaluated data from the World Health Organization (WHO) regarding the prevalence of cancer, cardiovascular disease, diabetes, infectious disease, and respiratory disease.
Statistical analysis revealed the following:
- Consumption of black tea has an impact on diabetes rates, but not on the other disease categories
- More specifically, drinking black tea reduces the risk of type 2 diabetes
- Countries topping the list for black tea drinkers are Ireland, the United Kingdom, and Turkey, with China, Brazil, and South Korea at the bottom of the list
Previous studies of black tea
This latest study is not the first time researchers have examined the benefits of black tea in relation to type 2 diabetes. For example:
A study in the Annals of Nutrition & Metabolism found that individuals with type 2 diabetes who regularly consumed black tea extract experienced antioxidative and anti-inflammatory effects, which the authors noted may "explain the mechanisms underlying the protective effects of drinking tea against cardiovascular disease."
Researchers at the Neurosciences Institute of the University of Dundee reported in 2008 that they had discovered black tea may fight type 2 diabetes because it contains substances (theaflavins and thearubigins) that acted like insulin. As you can see, that discovery fueled the current research.
Not every study has indicated that tea offers benefits in regard to diabetes, however. For example, an evaluation of green and black tea extracts was done in 49 adults who had type 2 diabetes. The three-month, placebo-controlled, double-blind study revealed that neither green nor black tea extract had a significant impact on hemoglobin A1c after three months.
The bottom line
Most evidence thus far suggests black tea has a positive role in type 2 diabetes. The results of this latest study, according to the authors, "are consistent with previous biological, physiological, and ecological studies conducted on the potential of [black tea] on diabetes and obesity."
Beresniak A et al. Relationships between black tea consumption and key health indicators in the world: an ecological study. BMJ Open 2012 Nov 8; 2
Cameron AR et al. Black tea polyphenols mimic insulin/insuli-like growth factor-1 signalling to the longevity factor FOXO1a. Aging Cell 7(1): 69-77
Li S et al. Black tea: chemical analysis and stability. Food & Function 2012 Oct 4
Mackenzie T et al. The effect of an extract of green and black tea on glucose control in adults with type 2 diabetes mellitus: double-blind randomized study. Metabolism 2007 Oct; 56(10): 1340-44
Neyestani TR et al. Regular daily intake of black tea improves oxidative stress biomarkers and decreases serum C-reactive protein levels in type 2 diabetic patients. Annals of Nutrition & Metabolism 2012; 57(1): 40-49