We all know that green tea has a huge amount of benefits, but did you know that drinking minimum of 6 cups of green tea daily can reduce your bad cholesterol and increase your good cholesterol.
CSIRO studies have shown that antioxidants in green tea can lower cholesterol in rabbits by increasing the amount of a liver protein that works to clear cholesterol from the blood.
Although research overseas has already linked green tea consumption with lower cholesterol levels, the CSIRO results are the first to identify the mechanism responsible.
Senior Research Scientist Dr Paul Roach says green tea's high concentration of strong antioxidants called catechins increase the liver's LDL receptors, a major mechanism for cholesterol control.
In turn these receptors work to decrease LDL, the so-called "bad cholesterol" in the blood.
"The LDL receptor binds LDL and clears it from the bloodstream," says Dr Roach.
Catechins are a type of polyphenol, a class of antioxidant and the main constituent of green tea. Black tea contains much lower levels of catechins because they are oxidised during processing.
The results of the rabbit study confirm previous CSIRO findings that green tea catechins increased the amount of LDL receptors in cultured human liver cells. Both studies were undertaken by PhD student Christina Bursill of the University of Adelaide's Physiology Department.
Studies by other researchers suggest that humans could lower their cholesterol levels by up to 10 per cent if they habitually consumed between 5 to 10 cups of green tea daily.
"The next step is to test the effectiveness of our green tea extract in humans with high blood cholesterol" says Dr Roach.
Note: This study was conducted in 2000 and Dr Roach has since left CSIRO.
From The October 1999 Issue of Nutrition Science News
Green Tea Lowers Cholesterol
Not only have Chinese researchers determined that certain chemicals in green tea lower cholesterol in animals, they've figured out how they work.
Ping Tim Chan and colleagues at the Chinese University of Hong Kong fed hamsters a high fat diet to raise their triglyceride and cholesterol levels to those of humans. They then fed the hamsters differing levels of epicatechins extracted from jasmine green tea for four to five weeks and compared them with hamsters that drank green tea and a control group that had water.
Epicatechins and green tea had exactly the same effect: Both lowered blood levels of triglycerides and cholesterol more than water. The effective doses researchers used are comparable to a person drinking three daily cups of tea. Animals drinking the human equivalent of 15 cups a day lowered both triglycerides and total cholesterol by a third. Epicatechins and green tea also lowered apoB, the main protein in harmful low density lipoprotein (LDL), by almost a half. ApoB levels predict heart disease more accurately than any cholesterol measure.
According to the researchers, epicatechins block cholesterol absorption and increase excretion of cholesterol-containing bile salts and fatty acids. The chemicals also speed the breakdown of triglycerides to fatty acids so they can be burned as energy. Other studies show that in addition to their effect on blood fats, epicatechins are powerful antioxidants that lower blood pressure and protect against cancer.
- Journal of Nutrition 1999 Jun;129:1094-101
More Information on Lowering Cholesterol
High cholesterol is one of the leading precursors to heart disease. And, research has shown that our diet and lifestyle, combined with our genetics determines whether we have healthy or unhealthy cholesterol levels. To keep your cholesterol levels in check and prevent heart disease, there are several measures you can take.
The first is diet. Cholesterol in food comes from animal products. Meat, eggs and dairy products are all culprits. Reduce the amount of red meat you consume, replacing it with fish or chicken. Use low fat dairy products and reduce the number of egg yolks you eat, or use egg substitutes. Increase the amount of fresh fruits and vegetables in your diet and eat whole grains rather than refined products like white flour.
The second is exercise. Be certain to get at least 30 minutes of exercise most days of the week. This will help you shed pounds if you need to, and will also help lower your serum cholesterol. Walking is a very good way to help get your daily dose of exercise.
In addition to making lifestyle and diet changes, many people take supplements to help control their weight and cholesterol levels. There are many supplements available, but one of the best is something you likely have in your cupboard right now. It’s tea – particularly green tea.
Asian cultures have consumed green tea in large quantities for centuries. And, throughout history they have had fewer problems with obesity and lower incidences of heart disease and many forms of cancer. Scientists are beginning to find a link between this high green tea consumption and better health. Much research has been performed on the ability of green tea to slow down the aging process and prevent illness.
The magic potion in tea seems to be its anti-oxidants. Anti-oxidants, which are also found in fruits and vegetables, wine, cocoa and coffee, fight our body’s free radicals. Free radicals are created as a by product of our digestive process, left unchecked these free radicals will damage our cells and DNA, leading to aging and disease. Anti-oxidants combat the free radicals before they can hurt our bodies and this is why it’s so important to have anti-oxidants as part of your every day diet. All tea contains anti-oxidants, but green tea retains more of its anti-oxidants in their original, natural state because it goes through less processing than other types of tea.
Green tea’s anti-oxidants have been shown to be effective at reducing cholesterol levels and helping with weight loss. Tea prevents the oxidation of LDL cholesterol into plaque, the hard substance that clogs our arteries, making us more susceptible to heart attacks and strokes.
Studies have suggested that even if your LDL cholesterol level is high, drinking tea may prevent it from causing a problem. Tea is also thought to have an anti-inflammatory effect, which helps the heart in its overall function.
In addition, green tea seems to have the ability to help patients lose weight. Losing weight usually means an automatic reduction in cholesterol levels; therefore green tea has a twofold effect on people who are overweight.
In terms of weight loss, it appears that the combination of the anti-oxidants in green tea and the caffeine speeds up the metabolism and promotes the oxidation of fat. Both of these will contribute to weight loss.
In recent years, there have been several studies on green tea’s ability to speed weight loss. One of the most interesting studies was conducted by Osaka University in Japan.
This study evaluated 98 men and 97 women, between the ages of 22 and 65. All subjects were healthy, though some were moderately overweight. The participants were divided into 3 groups. The first group received a placebo drink, the second group a green tea drink with a low dose of tea catechins (anti-oxidants) and the third group a green tea drink with a high dose of tea catechins.
The study was conducted over a 12 week period, during which time participants consumed their study beverage three times a day (at meals). At the end of the twelve week period, participants who received the green tea beverages had lost weight and reduced their body fat and BMI, unlike the group who consumed the placebo drink. The group with the higher dosage of tea catechins reported more success than the low dose group.
This study concludes the way countless others have in recent years: with the suggestion, at least, that drinking green tea can help you lose weight. And, losing weight can help you lower your cholesterol. In addition, other studies have shown that green tea may help lower cholesterol levels even in subjects who did not lose weight.