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Theaflavins Benefits, Side Effects & Dosage

Written by Aleksa Ristic, MS (Pharmacy) | Last updated:
Puya Yazdi
Medically reviewed by
Puya Yazdi, MD | Written by Aleksa Ristic, MS (Pharmacy) | Last updated:

Black tea contains theaflavins, powerful antioxidants that may reduce cholesterol and protect the brain. Scientists have been investigating their ability to combat infections, inflammation, aging, and more. Still, the clinical evidence is almost non-existent at this point. Read on to learn the potential benefits, side effects, and dosage of theaflavins.

What are Theaflavins?

Theaflavins are a class of natural flavonoids derived from the dried leaves of the plant Camellia sinensis (tea) and related plants with potent antioxidant properties. Flavonoids such as theaflavins neutralize free-radical species and increase the activity of detoxifying enzymes in the liver [1].

Black tea contains the highest concentrations of theaflavins because they are produced during fermentation [2].

People use theaflavin-rich black tea is used for headaches, low blood pressure, preventing heart disease, Parkinson’s disease, and more. However, the research on theaflavins as isolated compounds is still in the early phase [3].



  • Good antioxidants
  • May lower cholesterol
  • May improve fat and sugar metabolism
  • May have anti-HIV effects
  • May protect the brain


  • Most benefits lack clinical evidence
  • Unknown long-term safety

Antioxidant Properties

Polyphenols such as theaflavins are mainly responsible for antioxidant actions of black tea. These are manifested by its ability to inhibit free radical generation, scavenge free radicals, and bind transition metals [4].

Theaflavins inhibit the activity of enzymes that cause oxidative stress. Black tea is believed to be not only a popular pick-me-up beverage but also an anti-oxidative agent available in everyday life [4].

Potential Health Benefits

Insufficient Evidence:

No valid clinical evidence supports the use of theaflavins for any of the conditions in this section. Below is a summary of up-to-date animal studies, cell-based research, or low-quality clinical trials which should spark further investigation. However, you shouldn’t interpret them as supportive of any health benefit.

1) High Cholesterol

In 240 Chinese adults with high cholesterol, a theaflavin-enriched green tea extract (providing 75 mg of theaflavin daily for 12 weeks) reduced LDL cholesterol by 16% and total cholesterol by 11%, when combined with a low-fat diet [5].

Preliminary clinical research is promising and requires further investigation.

Animal and Cellular Research (Lacking Evidence)

No clinical evidence supports the use of theaflavins for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based studies; they should guide further investigational efforts but should not be interpreted as supportive of any health benefit.

2) Fat Metabolism

In animal and cellular models, theaflavins significantly reduced lipid accumulation and synthesis, while stimulating fatty acid oxidation. They improved fat metabolism by boosting AMPK [6].

3) Blood Sugar Levels

Theaflavins inhibit one of the enzymes that break down carbs into glucose: alpha-glucosidase. Consequently, they significantly reduced blood sugar levels upon maltose consumption in rats [7].

4) Anti-HIV Effects

In test tubes, theaflavins had potent anti-HIV activity by targeting the viral entry step. In the future, researchers may develop them as safe and affordable topical microbe killer for preventing sexual transmission of HIV [8].

5) Brain Protection

Based on animal and cellular research, tea polyphenols – mainly EGCG and theaflavins – may play an important role in delaying the onset and progression of Parkinson’s disease. The researchers underlined the need to further investigate the potential brain-protective effects of theaflavins [9].

In a 2019 study on mice, theaflavins reduced inflammation, memory impairment, and depressive symptoms caused by bacterial LPS. The authors noted that theaflavins had stronger anti-inflammatory and antioxidant effects than other tea polyphenols [10].

6) Gingivitis

In test tubes, theaflavins can affect the virulent properties of P. gingivalis and lessen the inflammatory response induced by this gingivitis. They may be a valuable therapeutic agent in oral health, but the available research is scarce [11].

7) Allergies

Theaflavins inhibited the fluctuations of cytokines and enhanced antioxidant status in allergic mice, leading to improvement in their symptoms. These results suggest that the theaflavins, as well as catechins, contribute to the anti-allergic effects of black tea [12].


The above studies were conducted in animals and test tubes, and we don’t know if theaflavins would have the same effects in humans.

Side Effects & Safety

No side effects of theaflavins were reported in the above clinical study, but their long-term safety remains unknown in the lack of stronger clinical evidence. Consult your doctor about other potential side effects, based on your health condition and possible drug or supplement interactions.

Due to the lack of safety data, children and pregnant women should avoid theaflavin supplements.


The below doses may not apply to you personally. If your doctor suggests using theaflavins, work with them to find the optimal dosage according to your health condition and other factors.

In the only clinical trial available, a theaflavin-enriched green tea extract (375 mg) providing 75 mg of theaflavin reduced LDL and total cholesterol in 12 weeks. Still, there’s not enough clinical data to establish a safe and effective dosage for a general population [5].

About the Author

Aleksa Ristic

Aleksa Ristic

MS (Pharmacy)
Aleksa received his MS in Pharmacy from the University of Belgrade, his master thesis focusing on protein sources in plant-based diets.  
Aleksa is passionate about herbal pharmacy, nutrition, and functional medicine. He found a way to merge his two biggest passions—writing and health—and use them for noble purposes. His mission is to bridge the gap between science and everyday life, helping readers improve their health and feel better.


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