This article covers a complete scientific study on the benefits associated with oolong tea. It is for you to learn the benefits of oolong tea, which will provide a new perspective to its characteristics and contents.
There are six forms of tea which include black, green, yellow, white, oolong, and dark teas from the plant Camellia sinensis. Out of these, oolong tea is a semi-fermented tea with its very own taste and aroma. It has also become a popularly consumed tea.
What Exactly is Oolong Tea?
Camellia sinenesis can be classified as a functional food as it contains naturally occurring bioactive substance. It is one of the most important functional foods and has held the second most popular beverage in consumption among all beverages. Tea contains over 4000 chemicals and some of which have health promoting properties. (source)Based on the stage of fermentation during processing, tea can be divided into two major types: green (unfermented tea), which is tea produced from fresh tea leaves and its enzymatic oxidation is inhibited by the process of steaming and pan-frying.
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Oolong tea (semi-fermented), which is made by wilting fresh leaves in the sun and then slightly bruising them. Semi-fermented oolong tea contains a mixture of catechins and their oxidized polymeric substances such as theaflavins and thearubigins. The taste quality of oolong tea depends on several properties, such as smell of volatile fragrance, taste sensation of sweetness, umami, and intensity of astringency.
Only 2% of oolong tea consumed mainly in Taiwan, southern China, and other Eastern countries. It has been noted that production and consumption of oolong tea worldwide have increased over the past decade. For example, the production of oolong tea in China from 2000 to 2014 had nearly doubled. (source)Oolong tea has been demonstrated to possess various pharmacological activities such as antioxidant, anti-obesity, anti-diabetes, antibacterial activities thus preventing effects of atherosclerosis, heart disease, hypertension.
Oolong tea contains Theasinensins, which is the end result of oxidation of catechins in tea leaves. This compound plays an important role and renders all the health benefits of oolong tea. Theasinensins found in oolong tea have innumerable biological properties that are associated with antihyperglycemic, anti-obesity, anti-inflammatory and anti-bacterial activities.
Theasinensins Occurrence in Oolong tea
According to this study, an experiment was conducted to show the absorption of theasinensins and to evaluate its transport pathway. It shows that in-vitro, i.e. when theasinensins was directly injected into the blood, system can help to circulate it faster than through oral consumption.
Antioxidant Effect of Theasinensins in Oolong TeaFRAP, which stands for Ferric Reducing Antioxidant Power, was tested on the anti-oxidant value of oolong tea and it ranges between 233 and 532 μmol/g. This range indicates a good amount of antioxidant strength in plant food. According to a study, there is a noticeable increase in the antioxidant capacity in human after the consumption oolong tea. It was noticed that there was a reduction in the oxidative stress, especially in the oxidative DNA damage.
A human study conducted on athletes showed that consumption of oolong tea significantly reduced the plasma malondialdehyde levels during the period of rest and post exhaustive exercise. This is suggested due to the reduction in oxidative stress that results from the reduction of the lipid peroxidation level and its free radical scavenging activity.
Studies have confirmed that the ethanol extract of oolong tea profoundly increased the adiponectin gene expression in epidydimal fat with a consistent anti-inflammatory effect. It also helps in the development of new blood vessels during the expansion of adipose tissues.
Anti-inflammatory Effect of Theasinensins in Oolong Tea
The formation of new blood vessels in adipose tissues contributes to the anti-inflammatory properties of oolong tea. Oolong tea consistently promotes the development of blood vessel. In turn, it promotes metabolism and protects the tissue from inflammation. The anti-inflammatory activity of oolong tea might be due to flavonoids such as catechins, theaflavins and theasinensins.
Recently, in clarifying the molecular mechanism of anti-inflammatory effects of theasinensin A, gene expression profiling in macrophage-like cells treated with theasinensin A through a genome-wide DNA microarray were used to detect the changes of 22,050 genes involving inflammatory and immune response.
The changes of 1382 genes suggested that theasinensin A has exerted anti-inflammatory effects by regulating the relevant expression networks of chemokines, interleukins, and interferons. (Source)
Anti-obesity Effect of Theasinensins in Oolong TeaIn these modern times, obesity is a major health issue and has become a key factor in metabolic disorders. Which is why, consuming foods that help in weight control is a logical approach. The anti-obesity effects of tea catechins, especially EGCG and theaflavins, appear to be related to modulation of energy balance, endocrine systems, food intake, lipid and carbohydrate metabolism and activities of different cell types including fat, liver, muscle and beta-pancreatic cells.
The tea catechins inhibit the formation of fats by lowering the regulation of gene expression of fatty acid in the nucleus. This further leads to the stimulation of cell energy in the mitochondria. Another process that helps in reducing fat from the body with the consumption of oolong tea is that it helps to inhibit the pancreatic lipase activity. This increases the excretion of lipid through body waste.
Another study has demonstrated that the oolong tea water extracts enhanced noradrenaline-induced lipolysis and inhibited pancreatic lipase activity, resulting in anti-obesity effects. This might be partially due to the effects of caffeine or some other bioactive compounds in oolong tea.
Supplementation with oolong tea leaves reduced body weights and plasma triacylglycerol, cholesterol and LDL-cholesterol. Pu-erh tea and oolong tea can significantly decrease the levels of triacylglycerol more significantly than green tea and black tea.
In addition, superoxide dismutase activity (SOD) was increased and the relative weight ratios of liver to epidydimal adipose tissue reduced by oolong tea. This study also suggested that oolong tea was more effective on their growth suppressive and hypolipidemic effects as compared to green tea.
Hypoglycemic Effect of Theasinensins in Oolong TeaHyperglycemia is the cause of diabetes in the blood vessels. A sodium dependent glucose transporter (SGLT1) transports glucose into the epithelial cells. Simultaneously it inhibits the uptake of glucose in the small intestine that may prevent hyperglycemia.
Oolong tea consumption has shown to increase the insulin in epidydimal cells and it also reduces the plasma glucose in people suffering from diabetes. Oolong tea is also great in assisting oral hypoglycemic agent in the treatment of type 2 diabetes.
An in vivo study with respect to type 2 diabetes subjects indicated that oolong tea remarkably reduced concentrations of plasma glucose from 229 to 162.2 mg/dL and fructosamine (from 409.9 to 323.3 μmol/L).Theasinensins might play a key role in anti-hyperglycemic activity of oolong tea and shows hypo-triacylglycerolemic effects by suppressing intestinal fat absorption in diabetic patients.
This study also strongly supports the concept of combination therapy because the ingestion of oral anti-hyperglycemic agents and oolong tea simultaneously was more effective in lowering plasma glucose than taking the drugs alone.
Antiseptic effects of theasinensins in oolong teaPathogens such as bacteria are mainly the cause of infections that can create health problems. Some bacteria, such as Staphylococcus aureus, are resistant to anti-biotics and the infection it causes can be difficult to cure than other infections. The aqueous extract of oolong tea inhibits various pathogens including Staphylococcus aureus according to a study.
Pathogenesis is linked with the ability to create water-insoluble compounds called glucans from sucrose and release acids from fermentable sugar. The extracts from oolong tea can help decrease the cellular surface hydrophobicity of bacteria and thus can inhibit their growth.
Thus, oolong tea extract demonstrates the process of pathogenesis, especially against oral streptococci. This was confirmed by a study conducted by Sasaki on the anti-bacterial properties of oolong tea. The study also suggested that the antibacterial activities of oolong tea is synergistic with other polyphenols and can easily bind with proteins.
As we all know, millions of people are affected by blood pressure. It is also associated with atherosclerosis and plaque build-up in the arteries. Both these factors are the causes of cardiovascular factors.
Inhibition of Atherosclerosis, Heart Disease, and Hypertension
Prevention of atherosclerosis also reduces the risk of hypertension and heart disease. According to a study, habitual and moderate oolong tea consumption can significantly reduce the risk of developing hypertension.The presence of low-density protein (LDL) is also a major risk factor in the early development of coronary heart diseases. Oolong tea effects the progression of atherosclerosis in patients and helps reduce the weight of the liver by reducing the adipose tissues as compared to green tea.
Intake of dietary fats are directly related with obesity and cardiovascular diseases, which is why it a logical to reduce the intake of lipid food. Burning more energy also reduces the incidences of atherosclerosis and heart disease. Another way of reducing fat is by the consumption of oolong tea, as the polyphenols in oolong tea increases the cholesterol excretion through body waste.
Furthermore, oolong tea also increases the energy expenditure which is higher than that of green tea. Thus, consumption of oolong tea causes increased metabolic rate and oxidation of fats. It can help to maintain a lower body fat content thus also reducing the risk of atherosclerosis and hypertension.
The characteristic compounds of oolong tea, theasinensins, have been reviewed for its chemical formation, corresponding biological properties and potential action against diseases. These clearly show the various health benefits of oolong tea.
Fine-tuned by the Zizira Editorial team