Tea Drinking Improves Cardiovascular Health

The medicinal properties of tea were highly regarded for centuries in the traditional medicine traditions of India and China. Team remains one of the most popular beverages in the world these days, enjoyed not only for its health benefits but also for its delightful taste. Not surprisingly, a simple Google search immediately reveals hundreds of articles, aimed to both academic and general public, which are dedicated to different health effects of tea drinking.

Modern science has identified a large variety of different compounds from different types of tea that have various effects on the human body. Most notably, a significant number of anti-oxidants were found in both green and black tea. They are considered to be key components for the beneficial effects of tea on the cardiovascular system.

However, the information available online is sometimes contradictory. Some claims of tea’s beneficial effects don’t seem to be confirmed by scientific research. The numbers reported by different researchers can also differ quite dramatically. So what is the hard scientific evidence in favor of tea drinking?

What's in that lovely cuppa?

The chemical composition of tea is very complex. The bulk of the positive effects is associated with so-called polyphenolic compounds, such as catechins, that possess antioxidant activity. Tea also contains vitamins, minerals, saccharides and many other components.

The three most commonly used varieties of tea include black tea, green tea and oolong tea. Active components of these varieties are not the same. Fermentation and processing can significantly change the composition of active ingredients in the beverage. The major antioxidants present in black tea are theaflavins.

Green tea contains catechin and several of its derivatives such epigallocatechin gallate (EGCG). EGCG is the major antioxidant in green tea. This is the best studied and the most active component of green tea.

Tea also contains alkaloids such as caffeine, theobromine, and theophylline. They provide the stimulating effect of tea. One of the amino acids found in green tea, L-theanine, is reported to have calming effects on the nervous system.

Medical evidence in favor of tea drinking

A number of studies indicate a significant positive effect of tea drinking on the reduction of cardiovascular risk. Scientific data suggest that black and green tea may reduce the risk of both coronary heart disease and stroke by between 10 and 20 percent respectively. Some estimates suggest that the regular consumption of tea reduces the risk of dying from heart attack by at least fifth.

Medical statistics from Japan strongly supports the benefits of tea drinking

Indirect evidence that the regular and long-term consumption of tea can have very positive effects on a person's health come from Japanese statistics. Japan has the lowest rate of cardiovascular diseases in the world, both among men and women. This is rather surprising taking into account the very high rate of smoking among Japanese males. Many researchers believe that this statistic is linked to the high level of green tea consumption in the Asian country. In Japan, green tea is consumed practically with every meal, and many people drink very significant amounts of this beverage on a daily basis.

Tea decreases the level of cholesterol and reduces chances of hypertension, atherosclerosis and obesity-related health problems

Green tea reduces the general level of cholesterol, as well as the level of so-called “bad” cholesterol. This, in turn, has a significant effect on a person's body weight. High consumption of tea results in better liver health, as well as in the protection of the pancreas.

Some studies show that green tea and oolong tea have a beneficial effect on hypertension. A group of Chinese researchers reported that regular consumption of green tea reduces the risk of hypertension by 46 percent. The antioxidant properties of green tea may also help prevent atherosclerosis, particularly coronary artery disease.

Excessive weights and obesity significantly increase the chances of cardiovascular diseases. Tea drinking leads to a more intensive metabolism, which results in faster fat oxidation and weight loss. Habitual tea drinkers have significantly lower percentage of body fat. This effect seems to be associated in a significant degree with the action of major antioxidant in green tea, epigallocatechin gallate (EGCG).

Tea drinking is known to reduce blood sugar and insulin levels. This leads to a powerful anti-diabetic effect. In the long run, this can lead to anti-aging effect and even a better life expectancy.

Proper scientific evaluation of tea benefits can be complicated

One of the complications with the studying of the effects caused by tea drinking is difficulty in comparing the research data coming from different laboratories. The content and amount of biologically active ingredients varies sufficiently from one type of tea to another that it becomes hard to assess the positive benefit of drinking "tea" as a concept.

For instance, the term “green tea” refers, literally, to several hundreds of varieties coming from different geographic regions with different climate and soil conditions. Green teas originate from different kind of tea plants. These varieties not only have a different taste but also differ significantly in terms of chemical composition.

On top of that, different teas are processed differently, and different methods of brewing are employed in different countries. As a result, Japanese and Chinese green tea have very different tastes, and there are significant differences even between different regions within each country. This consideration is important – many scientific publications report very different numbers when practically the same health-related parameters are studied.

As a result, there is a significant degree of confusion in some areas of medical research, particularly in regards to studying the effects of regular tea consumption on the development of some types of cancer. This problem is common for many studies that aimed to assess the efficiency of herbal medicine since all of them contain numerous components, and the variations between different experiments performed in different laboratories can be very significant.

The Mechanisms Behind The Positive Effects Of Tea

Direct effect on blood vessels and heart

The short- and long-term consumption of black tea leads to the increase of catechin concentration in blood. This is associated with improvements in the heart function among patients with coronary arterial disease. In particular, biologically active components of tea improve the functions of the endothelium – the tissues lining the blood vessels.

Endothelial dysfunction is linked to atherosclerosis and other cardiovascular diseases. It is associated with increased oxidative stress. Antioxidants can at least partially reverse this stress. The flavonoids found in tea tend to accumulate in endothelial tissues during long-term consumption and help in this process.

Improvement of glucose metabolism

Another mechanism associated with the positive effect of tea on cardiovascular health deals with an improvement in glucose metabolism. Tea exerts its action on glucose metabolism via inhibiting the enzyme called amylase. Amylase breaks down starch with the formation of glucose. The inhibition of amylase slows down this process, thus minimizing the rise of glucose level in blood.

Drinking tea helps in the slower release and intestinal absorption of glucose which, in turn, prevents the dangerous rise of the level of insulin. Insulin is a key hormone in regulating the metabolism of sugars and fats in human body. Insulin is involved in the development of obesity and it accelerates the aging processes in the body. Glucose intolerance increases with age and leads to various degenerative disorders including atherosclerosis. The down-regulation of glucose level helps in avoiding these problems. The regular consumption of tea leads to calorie restriction and has a positive effect on life expectancy.

Reduction of cholesterol level

A reduction of cholesterol levels helps to prevent obesity, improves liver and heart health, and protects the pancreas. A high level of blood cholesterol is directly linked to a higher risk of myocardial infarction. Green tea drinkers have a healthier level of “good” cholesterol. Scientific studies point out that the components of green tea block absorption of cholesterol in the intestine, as well as help body to excrete cholesterol.

Elimination of free radicals

All types of tea are rich in antioxidants. The positive effect of antioxidants on health in general and cardiovascular health in particular is well documented. Antioxidants exert their positive effects via combating the reactive oxygen species, and primarily various free radicals. Free radicals are formed in the normal process of metabolism inside the cells.

A cell has multiple mechanisms of eliminating them, but under certain circumstances the self-protecting capability of the cell can be overstretched. An unhealthy diet and smoking contribute to the increased level of reactive oxygen species, which is associated with various health problems and accelerated rate of aging. Free radicals can attack and damage the membrane on the surface of the cell. This damage contributes to the development of various cardiovascular diseases. Antioxidants are capable of catching and chemically neutralizing the radicals thus contributing to protection of cell membranes.

Some studies demonstrated that antioxidants from green tea are six times more efficient than those from black tea. Green tea’s catechin outperforms vitamin C by as much as 10 times in neutralizing the radicals.

It is often not known exactly which compounds are responsible for the protective effects of tea. Although many active compounds have been identified with known biological effects, tea contains many unidentified components with potential biological activity.

Current medical advice

Most researchers are positive in their conclusions about benefits of tea drinking and recommend at least a moderate consumption of this drink on a regular basis. Although many details still need to be investigated, the general positive effect of tea is now well proven scientifically. Green tea is richer with catechins and seems to produce more significant long term positive effects. It should be mentioned, however, that in 2006 the US Foods and Drug Administration (FDA) rejected the petition of tea makers who asked to allow them to write on the green tea packages that the drink reduces the chances of heart diseases.

FDA argued that the existing scientific data are insufficient, inconclusive, and therefore there are no credible evidences to support this claim. The mounting evidences coming from more recent research might eventually force FDA to reconsider its recommendation. Many individual components originating from tea are already approved by various national health authorities as beneficial health supplement and complimentary medicines for managing various health conditions and disorders.