Tea polysaccharide 茶多糖
Through a complex biochemical reaction, tea — especially green tea — helps sensitize cells so they are better able to metabolize sugar. Green tea is good for people with diabetes because it helps the metabolic system function better.”
A 2013 research review published in the Diabetes and Metabolism Journal outlined the potential benefits of tea when it comes to diabetes as well as obesity, which is a risk factor for diabetes. It highlighted a Japanese study that found that people who drank 6 or more cups of green tea a day were 33 percent less likely to develop type 2 diabetes than were people who drank less than a cup of green tea a week. It also reported on Taiwanese research that found that people who drank green tea regularly for more than a decade had smaller waists and a lower body fat composition than those who weren't regular consumers of green tea.
Drinking tea for diabetes is such a good idea because tea contains substances called polyphenols, which are antioxidants found in every plant. “Polyphenols help reduce oxidative stress and cause vasodilation (widening of the arteries), which decreases blood pressure, prevents clotting, and reduces cholesterol,” Dr. Steinbaum says. All of these activities reduce the risk for heart disease, which is elevated in people with diabetes. Polyphenols in green tea can also help regulate glucose in the body, helping to prevent or control diabetes.
Drinking Tea for Diabetes: Green Tea or Black Tea?
When it comes to drinking tea for diabetes, Steinbaum says benefits are tied to all teas, but that green tea is the clear winner. "For one, when you drink green tea for diabetes, you will get a higher level of polyphenols than you would get in black,” she explains. It’s the polyphenols in fruits and vegetables that give them their bright colors. So, having more color means that green tea is richer in polyphenols. “Of the black teas, the more orange the color, the higher the polyphenols,” she adds.
Besides its color, green tea also contains higher polyphenol levels because it's prepared from unfermented leaves, "so it is really pure,” Steinbaum says. Black tea, on the other hand, is made from leaves that are fully fermented, which robs it of some nutrients. “Plus, some black tea varieties can have two to three times more caffeine than green, which isn’t good in excess,” she says.
Polyphenols: Beyond Drinking Tea for Diabetes
The benefits of tea are clear. But besides tea, a number of foods high in polyphenols also can help prevent and manage type 2 diabetes. “The fruits highest in polyphenols areberries, grapes, apples, and pomegranates — because of their rich color,” Steinbaum says. Broccoli, onions, garlic, tomatoes, eggplant, and spinach are also good sources, as are cranberries, blood oranges, blackberries, blueberries, raspberries, strawberries, rhubarb, lemons, limes, and kiwis. “We know red wine contains resveratrol, which is a polyphenol — the highest concentration is in Bordeaux,” Steinbaum says.
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Cocoa is also a good source — a reason to eat a piece of dark chocolate now and then. “And for those following a vegetarian diet, there are also a number of foods high in polyphenols that also provide protein, such as red beans, black beans, pinto beans, pistachios, walnuts, chickpeas, and all the nut butters,” she says.
Overall, in addition to drinking tea for diabetes, eating a diet that’s good for your blood sugar isn’t complicated. “Type 2 diabetes tends to be driven by dietary lifestyle choices," Steinbaum says. "When we talk about prevention, having a diet filled with polyphenols will help the body better metabolize sugar." Hands down, eating foods rich in polyphenols — such as garlic and brightly colored fruits and vegetables — and drinking tea for diabetes, especially green tea, are great ideas for anyone trying to manage or prevent diabetes.
“When you say, ‘What is the best diet for diabetes?,’ people are hoping for this amazing plan," Steinbaum says. "But it really comes down to eating colorful fruits and veggies, nuts, drinking green tea, eating fish with omega-3 fatty acids, and getting a little cocoa and red wine — and you’re done."
Polyphenols can be further categorized into the following groups:
- phenolic acids
Possible health benefits and evidence
Polyphenols may help to reduce the risk of developing type 2 diabetes.
Many of the health benefits associated with polyphenols may be related to their role asantioxidants. Antioxidants are known for their ability to combat cell damage.
Polyphenols may also impact genes and gene expression. A person's specific genes can also affect how their body responds to certain types of polyphenols. Polyphenols may even influence gut bacteria.
Type 2 diabetes
Some researchers have reported that polyphenols may lower the risk fortype 2 diabetes. Polyphenols may boost insulin sensitivity, as well as slow down the rate the body digests and absorbs sugar.
According to one review, a type of flavonoid called flavan-3-ols may be especially beneficial for lowering insulin resistance. The same review also found that flavonoids seem to be the type of polyphenol most often associated with a lower risk for type 2 diabetes.
An analysis of studies on flavonoid intake and type 2 diabetes concluded that people who consumed the most flavonoids had a lower risk of developing type 2 diabetes than those who took in the least. Increasing flavonoid intake also appeared to be a way to reduce the risk of disease significantly.
Unprocessed cocoa is a rich source of flavonoids. One review found that cocoa consumption significantly decreased a marker of insulin resistance.
It is worth noting that unprocessed cocoa is very different from the chocolate in candy bars or traditional desserts. Unprocessed cocoa comes straight from the cacao plant with no sugar added.
A study in animals looked at the effect of green tea polyphenols on measures of inflammation after exercise.
Rats that received the tea polyphenols were able to keep up their activity for longer than the rats that did not receive the polyphenols. They also had significantly lower levels of chemicals that signaled inflammation and muscle damage in their blood.
Lignans are a class of polyphenols that occur at their highest levels in virgin olive oil, flaxseed, and whole grain rye flour. One way to study lignan intake is to look at levels of lignans in urine.
In a study of adults in the United States, researchers found that higher levels of lignans in the urine were associated with lower levels of measures of inflammation. This could be important since long-term inflammation has been associated with certain diseases, such as heart disease and cancer.
A review of studies looked at the impact of cocoa polyphenols on risk factors for heart disease. Scientists found that consuming cocoa for at least 2 weeks led to a significant decrease in blood pressure.
They also found that cocoa significantly decreased LDL or "bad"cholesterol, and raised HDL or "good" cholesterol.
Polyphenol intake may also play a role in body weight regulation.
One study compared the intake of flavonoids, a class of polyphenols, with body mass index (BMI) and waist circumference. Researchers found that a higher flavonoid intake was associated with lower BMI and waist circumference.
These results are significant because obesity is associated with a higher risk for many chronic diseases.