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Oolong Tea Extract

Also known as: Oolong Tea, Partially Fermented Tea, Camellia sinensis (Oolong Tea)

Overview

Oolong tea is a partially fermented tea derived from the leaves of the *Camellia sinensis* plant, placing it between green and black tea in terms of processing. It is consumed for its potential health benefits, including antioxidant properties, weight management, and cardiovascular health. Oolong tea contains bioactive compounds such as polyphenols (EGCG and theaflavins), tea polysaccharides, and L-theanine. Research on oolong tea is moderately mature, with epidemiological studies, randomized controlled trials (RCTs), and meta-analyses providing evidence for its effects. The quality of evidence varies, but many studies are of moderate to high quality. Oolong tea is generally considered safe for consumption, with potential side effects primarily related to its caffeine content. It is available in various forms, including loose leaf tea and extracts.

Benefits

Oolong tea consumption has been associated with several potential health benefits. A systematic review and meta-analysis found that oolong tea consumption reduced the risk of oral squamous cell carcinoma (OSCC) by 25-30%, with higher consumption (>500 mL/day) showing a greater reduction. However, a meta-analysis of RCTs showed that oolong tea intake did not significantly reduce postprandial triglyceride levels in healthy adults. Studies have also indicated that oolong tea extracts can help regulate blood pressure by influencing the renin-angiotensin system and endothelial function. A meta-analysis found no significant association between oolong tea consumption and bladder cancer risk. The reduction in OSCC risk was more pronounced among individuals with poor oral hygiene.

How it works

Oolong tea's mechanism of action primarily involves its polyphenol content, such as EGCG and theaflavins, which exhibit anti-inflammatory and antioxidant effects. These compounds can induce apoptosis or inhibit the proliferation of cancer cells, including oral cancer cells. Oolong tea extracts influence blood pressure regulation by affecting the renin-angiotensin system and endothelial function, as evidenced by changes in ACE, ET-1, and eNOS expressions. It interacts with the cardiovascular system by regulating blood pressure and lipid metabolism and with the immune system through its anti-inflammatory properties. The bioavailability of oolong tea polyphenols can vary but is generally considered to be moderate.

Side effects

Oolong tea is generally considered safe for moderate consumption. Common side effects include caffeine-related effects such as jitteriness, insomnia, and increased heart rate, especially in high doses. Uncommon side effects may include gastrointestinal issues like nausea and stomach upset. Rare side effects are not well-documented, but excessive consumption could potentially lead to more severe caffeine-related effects. Oolong tea may interact with certain medications, such as blood thinners, due to its caffeine and polyphenol content. Individuals with caffeine sensitivity or those taking certain medications should consult a healthcare provider before regular consumption. Pregnant or breastfeeding women should consume oolong tea in moderation due to its caffeine content.

Dosage

The minimum effective dose for health benefits is not well-defined, but consuming at least one cup per day is often cited in studies. For OSCC risk reduction, consuming more than 500 mL per day is associated with a greater reduction in risk. There is no established maximum safe dose, but high caffeine intake (above 400 mg per day) should be avoided. Timing of consumption does not appear to be critical for most benefits. Both brewed tea and extract forms can be effective, but the bioavailability may vary. Absorption can be influenced by the presence of other nutrients and individual metabolic factors. No specific cofactors are required for the benefits of oolong tea, but a balanced diet can enhance its effects.

FAQs

Is oolong tea safe to consume?

Oolong tea is generally safe, but high caffeine intake should be avoided, especially in sensitive individuals. Moderation is key to prevent potential side effects.

When is the best time to drink oolong tea?

There is no specific timing recommended, but it can be consumed with meals. Drinking it with meals may help with postprandial triglyceride levels.

What benefits can I expect from drinking oolong tea regularly?

Benefits such as reduced OSCC risk and potential blood pressure regulation can be expected with regular consumption. However, it is not a cure for any disease.

Is oolong tea a cure for cancer?

Oolong tea is not a cure for any disease but may contribute to overall health and wellness. It should be part of a balanced lifestyle.

Research Sources

https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2022.928840/full – This systematic review and meta-analysis found that oolong tea consumption reduced the risk of oral squamous cell carcinoma (OSCC) by 25-30%. Higher consumption (>500 mL/day) was associated with a greater reduction in risk. The study used propensity score matching and weighted logistic regression to minimize confounding effects, enhancing the reliability of the findings.
https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2016.00693/full – This meta-analysis of observational studies found no significant association between oolong tea consumption and the risk of bladder cancer. The study included multiple studies and adjusted for confounders, providing a comprehensive assessment of the relationship between oolong tea and bladder cancer risk.
https://libir.josai.ac.jp/il/user_contents/02/G0000284repository/pdf/JOS-03863603-46-1339.pdf – This systematic review and meta-analysis of RCTs found no significant reduction in postprandial triglyceride levels with oolong tea intake. The study was limited by a small sample size and potential publication bias, suggesting the need for further research in this area.
https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2022.892801/full – This study investigates the effects of oolong tea on blood pressure regulation, noting that oolong tea extracts can help regulate blood pressure by down-regulating the mRNA expressions of ACE and ET-1 and up-regulating eNOS. Oolong tea also reduced Ang II and ALD levels and elevated NO levels, which are important for blood pressure regulation.