Health Benefits of Tea: Scientific Insights

Potential Health Benefits: Green tea is rich in antioxidants, particularly catechins, which are believed to support multiple aspects of human health. Scientific studies suggest that consuming green tea may:

• Enhance metabolism and support weight loss.
• Lower the risk of heart disease and cholesterol levels through antioxidant properties and improved blood circulation.
• Support cognitive function and brain health.
• Reduce the risk of certain chronic diseases due to its anti-inflammatory and antioxidant effects.

Caution: Excessive consumption may lead to iron deficiency due to its high tannin content, which can inhibit iron absorption.

Supporting Literature:

1) " A New Function of Green Tea: Prevention of Lifestyle-related Diseases" (The New York Academy of Science) – This article provides evidence that green tea has preventive effects on both chronic inflammatory diseases and lifestyle-related diseases (including cardiovascular disease and cancer), resulting in prolongation of life span.

2) "A comprehensive review on the effects of green tea and its components on the immune function" (ScienceDirect) – This research highlights that green tea extracts and compounds have the possibility of modulating the innate immune system, adaptive immune system, and intestinal immune system. In immune-related diseases, tea polyphenols are the most significant compounds that modify immune functions, though other compounds are being investigated and cannot be ruled out.

3) “Neurological mechanisms of green tea polyphenols in Alzheimer's and Parkinson's diseases” (The Journal of Nutritional Biochemistry) – This study confirms that green tea polyphenols are now being considered as therapeutic agents in well controlled epidemiological studies, aimed to alter brain aging processes and to serve as possible neuroprotective agents in progressive neurodegenerative disorders such as Parkinson's and Alzheimer's diseases.

Potential Health Benefits: Oolong tea, a partially fermented tea, offers various health benefits due to its antioxidant, fluoride, and anti-inflammatory properties. Scientific studies suggest that Oolong tea may:

• Promote fat burning
• Support cognitive function
• Lower blood sugar, support the treatment of type 2 diabetes
• Potentially reduce the risk of certain diseases like heart disease and cancer
• Help prevent cavities and reduce the risk of tooth loss

Supporting Literature:

1) “Multifunctional health-promoting effects of oolong tea and its products” (ScienceDirect) – The study summarizes that Oolong tea ‘contains a variety of phytochemicals benefiting to human health, especially polyphenols and polysaccharides. It exhibits important cancer chemo preventive function’.

2) “Antihyperglycemic Effect of Oolong Tea in Type 2 Diabetes” (PubMed) – The study indicates that Oolong tea ‘may be an effective adjunct to oral hypoglycemic agents in the treatment of type 2 diabetes’. 

3) “Beneficial effects of oolong tea consumption on diet-induced overweight and obese subjects” (PubMed) – The study concludes that ‘Oolong tea could decrease body fat content and reduce body weight through improving lipid metabolism. Chronic consumption of oolong tea may prevent against obesity.’

4) “Association between tea consumption and risk of cognitive disorders: A dose-response meta-analysis of observational studies” (PubMed) – The meta-analysis involved 17 studies with 48,435 participants showed that ‘a higher tea consumption was associated with a significant reduction in the risk of cognitive disorders.’ As such, ‘tea consumption is inversely and linearly related to the risk of cognitive disorders. More studies are needed to further confirm our findings.’

Potential Health Benefits: Black tea is a fully oxidized tea from the Camellia sinensis plant, known for its robust, often malty flavor and darker color compared to other tea types. Scientific studies suggest that Pu-erh tea may:

• Improve cardiovascular health
• Support diabetic control
• Support mental alertness, helps with stress recovery, and improves gut health 
• Help prevent cavities and reduce the risk of tooth loss 
• Effective in relieving constipation with aged black tea (stored for more than 2      years)

Supporting Literature:

1. “Health-Promoting Effects of Black Tea: A Narrative Review of Clinical Trials” (PubMed) – ‘Findings from clinical trials indicated that consuming black tea regularly enhances endothelial and vascular health, notably by improving flow-mediated vasodilation. These advantages are largely due to the tea's antioxidant, anti-inflammatory, and gut microbiota-modulating effects, including the promotion of beneficial bacterial species such as Flavonifractor plautii. Effects on metabolic health, such as lipid profiles and glucose metabolism, were inconsistent. However, black tea was linked to improved cognitive function, especially attention and alertness, likely due to caffeine and L-theanine.’

2. “Black tea consumption improves postprandial glycemic control in normal and pre-diabetic subjects” (PubMed) – This study concludes that ‘Black tea consumption can decrease postprandial blood glucose after sucrose intake.’

3. “Association between tea types and number of teeth: a cross-sectional study of the Chinese Longitudinal Healthy Longevity Survey” (PubMed) – The study aimed to determine the association between residual teeth and consumption habits of different types of tea in older adults, and the findings include, ‘Long-term green tea consumption in males and black tea consumption in females were significantly associated with maintaining functional dentition (≥20 teeth). Similarly, long-term green tea consumption in males and green tea and scented tea consumption in females were associated with avoiding severe tooth loss (≥10 teeth). Furthermore, in the daily tooth brushing group, long-term consumption of black tea was associated with avoiding severe tooth loss in both sexes. However, tea consumption alone had no effect on oral health without good brushing habits.’

4. “The effects of tea on psychophysiological stress responsivity and post-stress recovery” (PubMed) – The study concludes that ‘Compared with placebo, 6 weeks of tea consumption leads to lower post-stress cortisol and greater subjective relaxation, together with reduced platelet activation. Black tea may have health benefits in part by aiding stress recovery.’

5. “Aged black tea alleviates constipation in mice by modulating intestinal neurotransmitters and decreasing AQP3 and AQP9 expression” (PubMed) – The researchers believe that ‘regular consumption of black tea is effective in relieving constipation, and that black tea is more effective in relieving constipation as the storage time increases.’

Potential Health Benefits: Pu-erh tea is a fermented variety of green tea known for its distinct health-promoting properties. Scientific studies suggest that Pu-erh tea may:

• Aid digestion and promotes gut health through its probiotic content.
• Lower blood sugar levels and support heart health.
• Support weight management by boosting metabolism and reducing fat accumulation.
• Act as a natural detoxifier, promoting overall wellness.

Supporting Literature:

1. “Reduction of body fat and improved lipid profile associated with daily consumption of a Pu'er tea extract in a hyperlipidemic population: a randomized placebo-controlled trial” (PubMed)  – The study suggests that, ‘daily consumption of Pu'er tea  extract supports improved cardiovascular health in several ways, including weight management through loss of body fat and beneficial changes to blood  lipids, specifically with respect to reduced triglycerides and very low-density lipoprotein.’
2. “A randomized double-blind placebo-controlled study of Pu'er tea extract on the regulation of metabolic syndrome” (PubMed) – The study concludes that, ‘Pu'er tea demonstrated excellent potential in improving central obesity, adjusting blood lipid, lowering blood sugar, regulating immunity and resisting oxidation. It can adjust the metabolic syndrome of different clinical phenotypes to different degrees and is  ideally fit for early prevention of metabolic syndrome.’
3. “Pu-erh Tea Protects the Nervous System by Inhibiting the Expression of Metabotropic Glutamate Receptor 5” (PubMed) - The results indicate that ‘Pu-erh tea markedly decreased the transcription and translation of mGluR5 compared to those by black and green teas.      Pu-erh tea also inhibited the expression of Homer, one of the synaptic scaffolding proteins binding to mGluR5.Pu-erh tea contains biological   compounds that bind transcription factors and inhibit the expression of  mGluR5 and identifying pu-erh tea as a novel natural neuroprotective agent.’
4. “Pu-Erh  tea and GABA attenuates oxidative stress in kainic acid-induced status epilepticus” (PubMed), The findings confirm that, ‘Taken together, Pu-erh tea leaf and GABA have neuroprotective effects against excitotoxins that may have clinical applications in epilepsy.’

Potential Health Benefits: it contains the antioxidant gingerol, which is the main bioactive disease-fighting compound found in ancient ginger root. Ginger also contains trace amounts of vitamins and minerals such as vitamin B3 and B6, iron, potassium, and vitamin C. Scientific studies suggest that ginger may,

• Boost the immune system and combat inflammation. 
• Help treat a range of ailments, such as gastrointestinal function, pain, inflammation, metabolic syndromes, and more.
• Slow blood clotting; however, 
• It can be potentially dangerous for people taking antiplatelet drugs like aspirin or clopidogrel, or anticoagulant drugs. Also, ginger can cause extra bleeding during and after surgery.

Supporting Literature:

1. “Ginger on Human Health: A Comprehensive Systematic Review of 109 Randomized Controlled Trials” (PubMed) – The study reviewed 109  eligible papers covering the clinical effects of ginger in all reported areas, and it agreed that ginger was effective when used as treatment to lessen nausea and vomiting in pregnancy, inflammation, metabolic syndromes,      digestive function, and colorectal cancer’s markers.