Oolong Tea: Uses, Benefits, Side Effects By Dr. Rajeev Singh

Introduction:

Tea consumption has a long and interesting history that dates back to 2007 BC. According to Chinese mythology, a ruler Shen Nong discovered the stimulating properties of tea by accident 4000 years ago. During a summer visit to a distant region of his country, he halted for rest. The servants began boiling water for the ruler to drink by his decision that the drinking water needed to be boiled as a hygienic precaution. The water turned a dark brown as some leaves from an adjacent tree fell into it. The beverage fascinated the ruler. Chinese history claims that this ancient ruler was the first person to drink tea. Oolong tea is a semi-fermented type of tea. It is a beverage prepared from the leaves of Camellia sinensis and originated in ancient China. It is one of the best health-protective non-alcoholic beverages. No wonder it is also termed as a ‘nutraceutical drink’.¹ Let’s read and find out more about this brewed oolong tea. 

Nutritional Value of Oolong Tea:

100g of oolong tea possesses the following nutrients.³ 

• Water: 99.8g 
• Ash: 1kcal 
• Carbohydrate: 0.02g 
• Calcium (Ca): 0.15g
• Magnesium (Mg): 1mg 
• Phosphorus (P): 1mg 
• Potassium (K): 12mg  
• Sodium (Na): 3mg
• Zinc (Zn): 0.01mg
• Manganese (Mn): .21mg 
• Caffeine: 16mg 
• Theobromine: 2mg

Along with these, oolong tea contains vitamin B3 (Niacin) 0.06mg.³ 

Properties of Oolong Tea:

Some of the oolong tea properties are as follows:²  

• It might have antioxidant activity. 
• It might have anti-inflammatory activity. 
• It may show an immune-regulatory effect. 
• It might also act as a neuroprotective agent which may help with depression. 

Potential Uses of Oolong Tea for Overall Health:

Drinking oolong tea every day may have health benefits which are as follows:  

1. Potential Uses of Oolong Tea for Breast Cancer

In 2018, Haihong Shi et al. researched the effects of oolong tea against breast cancer. The results showed that catechins present in oolong tea might induce DNA damage which may be helpful against breast cancer cell growth. As a result, it might be helpful in the management of breast cancer.⁴ However, kindly consult the neurologist for diagnosis and treatment. Furthermore, avoid using oolong tea as self-medication, as there could be severe side effects.  

2. Potential Uses of Oolong Tea for Postprandial Hyperlipidaemia

Postprandial hyperlipidemia is a condition caused by consuming fat-rich meals during the day. It is characterized by high serum triglyceride levels. Suzuki et al., 2018 discovered that oolong tea-polymerized polyphenols (OTPP) might inhibit the pancreatic enzyme lipase. Pancreatic lipase breaks the fats in our food, which get absorbed in the intestine. OTPP in oolong tea may inhibit the absorption of lipids in the gastrointestinal tract and increase lipid elimination.⁵ However, more research is needed to check the effects of oolong tea in this condition. Kindly consult the doctor for diagnosis and treatment.  

3. Potential Uses of Oolong Tea for Obesity

Obesity is a condition characterized by an imbalance in energy intake and expenditure. This can result in various diseases, including hypertension, type II diabetes, coronary artery disease and cancer. According to Wu et al., 2018, tea polysaccharides mixed with polyphenols (TPSM) in oolong tea might effectively manage obesity. Oolong tea consumption might reduce the rate of food intake. It may also inhibit the body from absorbing fatty acids, reducing obesity. It also proved that contents present in oolong tea, along with TPSM, might be effective in weight management.⁶ However, more research is required to find out the use of oolong tea for obese patients. So, please consult a physician for a diagnosis and treatment if you have weight-related concerns. 

4. Potential Uses of Oolong Tea for the Liver

Venkatakrishnan et al. in 2018 researched that oolong along with other teas may show hepatoprotective effects. It may reduce oxidative stress by enhancing the antioxidant defense system. It might also reduce inflammation, stop liver cell death and control lipid metabolism. In addition, it may avoid liver fat accumulation.² However, more research is required to demonstrate the effects of oolong tea on the liver. So, please consult the doctor for all liver-related diagnoses and treatment. 

5. Potential Uses of Oolong Tea for Blood Pressure

In a study by Xin et al. in 2022, rats on a high-salt diet had their blood pressure tested before and after drinking tea. The results showed that the consumption of oolong tea lowered blood pressure. Along with lowering blood pressure, it may also be helpful in the management of hypertrophy and necrosis of cardiomyocytes which are the conditions that may contribute to heart failure.⁷ Nonetheless, please consult a doctor for diagnosis and treatment if you suspect blood pressure or heart-related symptoms. Avoid self-medication as it could lead to the worsening of the condition. 

6. Potential Uses of Oolong Tea for Kidneys

In a study by Xin et al. done in 2022, kidney tissue damage was studied in rats on a high-salt diet before and after drinking tea. It showed that oolong tea consumption might help recover from kidney damage. It may also lower the necrosis (death) of renal tubular epithelial cells, the main cause of kidney injury.⁷ However, the effects of oolong tea on the kidneys require further research. Therefore, please consult a doctor for all kidney-related concerns and do not self-medicate. 

7. Other Uses of Oolong Tea:

• It might reduce blood glucose levels and help in the management of diabetes.¹ 
• Oolong tea may improve intestinal microorganisms growth, which are the bacteria that live inside the intestines. It may be helpful in the management of inflammatory bowel disease and aid in digestion.⁷  
• It might lower oxidative stress, a situation where the body’s cells contain excessive free radicals.⁷   

Though there are studies that show the benefits of oolong tea in various conditions, these are insufficient and there is a need for further studies to establish the true extent of the benefits of oolong tea on human health.  

Based on some studies I came across, oolong tea is a good source of l-theanine that helps in reducing anxiety and improving attention and alertness. Additionally, l-theanine might also be useful in managing cognitive disabilities like Parkinson’s disease or Alzheimer’s disease in elderly patients.

Dr. Siddharth Gupta, B.A.M.S, M.D (Ayu)

How to Use Oolong Tea?

We can consume oolong tea to get the discussed benefits. Dried tea leaves are brewed in boiling water and strained into a cup.  

You must consult a qualified doctor before taking any herbal supplements. Do not discontinue or replace an ongoing treatment of modern medicine with an ayurvedic/herbal preparation without consulting a qualified doctor.   

Side Effects of Oolong Tea:

• Drinking excessive amounts of oolong tea may prevent the body from absorbing iron in the diet, which might result in iron-deficiency anaemia.²  

Consult the ayurvedic doctor who prescribed it to you. They will be able to identify the issue and help solve it.   

Based on my observations, oolong tea (Camellia sinensis) leaves’ extract can be used for its multiple medicinal properties. Some studies show that oolong tea might have beneficial effects on many oral diseases, namely gum diseases and dental caries to name a few.

Dr. Rajeev Singh, BAMS

Precautions to Take with Oolong Tea:

• Oolong tea must not be taken with food, especially iron-rich foods, as it might cause severe side effects.  
• Brewed oolong tea has a shelf life of 2 years if stored well.  
• Children, the elderly, and pregnant and lactating women must avoid oolong tea if allergic to it. A doctor’s opinion is a must before administering oolong tea to them. 
• You must avoid oolong tea in excess, as it might cause side effects.  

Interactions with Other Drugs:

• Some tea constituents have been identified as having anti-nutritive properties. For example, trypsin, lipase, amylase, and glucosidase, which are involved in the digestion of protein, lipids and carbohydrates, may be inhibited by tea tannins and polyphenols. This results in a decrease in the availability of these nutrients, which may harm malnourished people. However, please consult an ayurvedic doctor for an accurate diagnosis and treatment. 
• Tea contains an anti-thiamine substance that may inhibit thiamine’s bioactivity. It may result in peripheral and central nervous dysfunction. Kindly consult the doctor for better health results. 
• Caffeine (more than 200 mg/d or approximately 3-4 cups/day) combined with tea consumption may result in short-term nervous system stimulation, insomnia, anxiety, tremor and increased blood pressure. Please consult the doctor for proper diagnosis and treatment. 

Frequently Asked Questions (FAQs)

References:

1. Tang GY, Meng X, Gan RY, Zhao CN, Liu Q, Feng YB, Li S, Wei XL, Atanasov AG, Corke H, Li HB. Health functions and related molecular mechanisms of tea components: An update review. International journal of molecular sciences. 2019 Dec 8;20(24):6196. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6941079/pdf/ijms-20-06196.pdf 
2. FoodData Central. Beverages, tea, Oolong, brewed [Internet]. Department of Agriculture. [Cited 2022, Nov 15] Available from: https://fdc.nal.usda.gov/fdc-app.html#/food-details/174120/nutrients 
3. Shi H, Liu J, Tu Y, Freter CE, Huang C. Oolong tea extract induces DNA damage and cleavage and inhibits breast cancer cell growth and tumorigenesis. Anticancer Research. 2018 Nov 1;38(11):6217-23. Available from: https://ar.iiarjournals.org/content/anticanres/38/11/6217.full.pdf 
4. Suzuki R, Fujita S, Kawasaki T, Honda1l Y, Shirataki Y. Effects of Oolong Tea on Postprandial Triglyceride Levels. Available from: https://core.ac.uk/download/pdf/188212146.pdf 
5. Wu T, Xu J, Chen Y, Liu R, Zhang M. Oolong tea polysaccharide and polyphenols prevent obesity development in Sprague–Dawley rats. Food & nutrition research. 2018;62. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6303733/pdf/FNR-62-1599.pdf 
6. Ye X, Tang X, Li F, Zhu J, Wu M, Wei X, Wang Y. Green and Oolong Tea Extracts With Different Phytochemical Compositions Prevent Hypertension and Modulate the Intestinal Flora in a High-Salt Diet Fed Wistar Rats. Frontiers in Nutrition. 2022;9. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9121855/pdf/fnut-09-892801.pdf 

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