Black Tea Fights Diabetes by Science Daily (7/28/09), Institute of Food Technologists (7/28/09) and Dr. Mercola
Black tea, long known for its antioxidants, immune boosting and
antihypertensive properties, could have another health benefit.
Researchers studied the polysaccharide levels of green, oolong
and black teas and whether they could be used to treat
Polysaccharides, a type of carbohydrate that includes starch and
cellulose, may benefit people with diabetes because they help
retard absorption of glucose.
The researchers found that of the three teas, the
polysaccharides in black tea had the most glucose-inhibiting
properties. The black tea polysaccharides also showed the highest
scavenging effect on free radicals, which are involved in the onset
of diseases such as cancer and rheumatoid arthritis.
Dr. Mercola's Comments:
While this study was done with black tea, which is
the most common form of tea consumed in the US, it is not as
healthy as green teas, which essentially have the same benefits but
are less damaged as they go through less processing.
All teas, black, green and oolong, are all derived from the
Camellia sinensis evergreen plant. The difference between the teas
comes from the amount of oxidation and type of processing each tea
Oxidation is the main deciding factor whether you have green,
oolong, or black tea, as the oxidation process causes the leaves to
turn bright copper or black in color.
Whereas black tea undergoes the most amount of oxidation through
application of high heat, high quality green tea is not oxidized at
all. This is how you can tell the quality of your green tea; the
greener, the higher the quality as it signifies the least amount of
While the rest of my comment addresses the study, please realize
that my strong recommendation would be to consider green or herbal
teas instead, which I believe are superior.
How Tea Benefits Diabetics
This is not the first time researchers have found tea to be
beneficial, especially for diabetics. And although I still believe
water should be your beverage of choice and make up the majority of
your fluid intake, adding tea to your day is a sensible choice with
many health benefits.
This latest study concentrated on a natural polysaccharide
compound that mimics type 2 diabetes drugs Precose and Glyset.
Compared to green and oolong tea, black tea was found to contain
the most of this particular substance.
The tea polysaccharides reduce your blood sugar by inhibiting
alpha-glucosidase, an enzyme that turns starch into glucose. The
two drugs mentioned above work by inhibiting this enzyme as
But it's quite likely that there's more than one master
ingredient that gives black tea its power to be of help against
In another recent study, participants who drank black tea had
significantly reduced plasma glucose concentrations after two
hours, compared to those who drank water or caffeine drinks.
Drinking black tea also increased insulin levels, compared with the
That study linked black tea's diabetic benefits to polyphenols
(naturally occurring antioxidants), including:
- Epigallocatechin gallate (EGCG)
- Epicatechin gallate
These compounds are thought to work by stimulating your B-cells
-- pancreatic cells responsible for insulin production -- to
produce insulin in your body. A growing body of research also
suggests that the polyphenols in tea can lower your cholesterol,
triglyceride levels and blood pressure, and even help to protect
Epigallo-catechin gallate (EGCG), specifically, has shown
potential to fight a number of diseases aside from diabetes,
- Alzheimer's disease
Specific health benefits of EGCG include:
- Improved exercise performance
- Regulatory effect on fat metabolism
- Improved digestion
- Reduced risk of heart disease (3+ cups/day)
- Improved antioxidant status (1-6 cups/day)
Quality and Purity May Be More Important Than
the Type of Tea You Drink
Fluoride is not what most people think about when they think
about tea, but it is a common contaminant in many teas.
Fluoride is a toxic substance that can have profoundly negative
effects on your body. So, when I make the recommendation to drink
tea, it's with the caveat that the tea be of high quality and free
Green tea is the least processed kind of tea, and therefore
typically contains the least amount of fluoride and the most EGCG
of all tea varieties. Aside from water, I believe high-quality
green tea is one of the most beneficial beverages you can
I prefer matcha green tea because it contains the entire ground
tea leaf, and can contain over 100 times the EGCG provided from
regular brewed green tea.
In addition, I also recommend drinking your tea "straight,"
avoid adding sugar, artificial sweeteners, milk or other unhealthy
Green Tea May Be the Healthiest Choice of
Although black tea was found to contain more glucose inhibiting
polysaccharides, green tea may still be the most beneficial tea of
them all, including for diabetics.
One previous study found that EGCG in green tea worked as well
in moderately diabetic mice as GlaxoSmithKline's diabetes drug
Avandia, for example.
Another study in the European Journal of Clinical Nutrition
concluded that green tea-extract also had a positive impact on
glucose abnormalities. In that study, daily supplementary intake of
green tea-extract lowered the hemoglobin A1c level in individuals
with borderline diabetes.
How is Matcha Green Tea Different From Other
Many green teas have been oxidized, and this process
may take away many of its valuable properties. The easiest sign to
look for when evaluating a green tea's quality is its color: if
your green tea is brown rather than green, it's likely been
The matcha tea is a vibrant bright green, and is far less processed
and of much higher quality than most other green teas, so you also
avoid the risk of ingesting high levels of fluoride, lead, and
aluminum, which can be found in inferior teas of all kinds,
including green teas.
Rather than being steeped and strained like typical tea, matcha tea
is made of tea leaves ground into a powder, and you add the powder
right into the water. Since you are consuming the whole leaf in
this way, matcha tea is said to be one of the healthiest green teas
Preventing and Treating Diabetes
Back to Health
Clearly, if you have diabetes then medication is not the answer
you're looking for.
Doctors usually talk about diabetes as a disease of blood sugar.
However, type 2 diabetes is more correctly a disease of insulin and
leptin signaling -- both of which can be corrected through proper
diet and exercise.
So before resorting to drugs for diabetes, I suggest learning about
how food and exercise can be your allies to better health, and
adding a few cups of green tea to your day could be one beneficial