Oolong Tea Leaf 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, buds, and stems of the _Camellia sinensis_ plant. This processing method distinguishes it from green tea (unfermented) and black tea (fully fermented). It contains various phytochemicals, including catechins (EGCG, EGC), polyphenols, flavonoids, L-theanine, and caffeine, with composition varying by source and processing. Oolong tea is consumed for potential health benefits such as improved mental alertness, prevention of diseases like cancer, tooth decay, osteoporosis, and heart disease, as well as aiding in weight loss and diabetes management. Research on oolong tea is substantial, with numerous studies on its health benefits, though more systematic reviews are needed to consolidate the evidence. The available evidence includes randomized controlled trials (RCTs) and some systematic reviews, providing a moderate to high level of evidence for its health benefits.
Benefits
Oolong tea offers several evidence-based benefits. Studies indicate it can regulate blood pressure by modulating angiotensin II (Ang II), aldosterone (ALD), and nitric oxide (NO) levels; one study showed oolong tea having a stronger regulatory effect than green tea. Research also suggests it aids in weight loss; a study in overweight and obese Chinese adults found that consuming 300 mL of oolong tea four times a day for 6 weeks resulted in over half the participants losing over 1 kilogram. Additionally, oolong tea exhibits antioxidative properties, increasing plasma vitamin C levels and ORAC activity in mice under stress. It may also contribute to cardiovascular health by lowering cholesterol levels. These benefits are generally applicable, with specific studies focusing on overweight individuals and those with high-salt diets. Significant reductions in blood pressure and body weight have been observed in studies.
How it works
Oolong tea affects blood pressure regulation through the renin-angiotensin-aldosterone system (RAAS), reducing Ang II and ALD levels while increasing NO levels. Its antioxidative effects are mediated by scavenging free radicals and enhancing plasma ORAC activity and vitamin C levels. The tea interacts with the cardiovascular system by improving blood pressure and lipid profiles. Caffeine content stimulates the central nervous system (CNS), heart, and muscles. Catechins, particularly EGCG, target molecular pathways involved in inflammation, oxidation, and cardiovascular health. The bioavailability of active compounds can be enhanced by steeping the tea for a longer duration to increase flavonoid extraction.
Side effects
Oolong tea is generally safe for consumption, but side effects can occur due to its caffeine content. Common side effects include caffeine-related issues such as jitteriness, insomnia, and increased heart rate. Uncommon side effects may involve gastrointestinal issues like nausea and stomach upset. Rare side effects include allergic reactions. 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 interacting medications should use oolong tea with caution. Pregnant or breastfeeding women should consume oolong tea in moderation due to its caffeine content.
Dosage
While a minimum effective dose isn't well-established, consuming 2-3 cups per day is a common recommendation. Studies have used dosages such as 300 mL of oolong tea four times a day. There is no established maximum safe dose, but high caffeine intake should be avoided. Oolong tea can be consumed at any time, but it is best to avoid it close to bedtime due to its caffeine content. Steeping oolong tea for a longer duration can increase the extraction of beneficial flavonoids. The bioavailability of oolong tea's active compounds can be influenced by the steeping time and method of preparation.
FAQs
Is oolong tea safe?
Oolong tea is generally safe, but individuals sensitive to caffeine should be cautious due to potential side effects like jitteriness and insomnia.
When is the best time to drink oolong tea?
It is best to consume oolong tea during the day to avoid sleep disturbances, as it contains caffeine.
What results can I expect from drinking oolong tea?
With regular consumption, significant health benefits such as blood pressure reduction and weight loss can be expected, as part of a balanced lifestyle.
Is oolong tea a quick fix for weight loss?
Oolong tea is not a magic bullet for weight loss or health; it should be part of a balanced diet and lifestyle to achieve optimal results.
Research Sources
- https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2022.892801/full – This study investigated the effects of green tea and oolong tea on blood pressure in rats on a high-salt diet. The key finding was that oolong tea significantly reduced blood pressure by regulating Ang II, ALD, and NO levels, showing a stronger regulatory effect than green tea, suggesting potential benefits for managing hypertension.
- https://www.science.gov/topicpages/g/green+tea+oolong.html – This study focused on the antioxidative effect of oolong tea using in vitro and in vivo methods. The results showed that oolong tea extract increased ORAC activity and plasma vitamin C levels in mice under restraint stress, indicating antioxidative properties that could help mitigate oxidative stress.
- https://www.medicalnewstoday.com/articles/319276 – This article provides a general overview of oolong tea, highlighting its potential benefits for weight loss, heart health, and mental alertness. It emphasizes the presence of antioxidants and other beneficial compounds in oolong tea that contribute to these health effects.
- https://www.rxlist.com/supplements/oolong_tea.htm – This resource offers information on oolong tea as a supplement, including its uses, potential side effects, and interactions. It serves as a reference for understanding the safety profile and appropriate usage of oolong tea.
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