Theaflavins (TFs) are pigments formed during the processing of tea leaves, derived from the oxidation and polymerization of tea polyphenols and their derivatives. They are water-soluble compounds with a phenylpropanoid ketone structure, containing multiple hydroxyl or phenolic hydroxyl groups. The content of theaflavins in black tea ranges from 0.3% to 1.5% of the solids and plays an important role in the color, flavor, and overall quality of the tea. Theaflavins are crucial components in the color and flavor of black tea, and they are also key to the formation of the “golden ring” in tea. Research has shown that the higher the theaflavin content in black tea, the brighter the tea’s color and the better the sensory quality.
In addition to being used as a food antioxidant, studies have found that theaflavins, as a green, natural, efficient, and safe natural product, have significant health benefits, such as antioxidant, anti-inflammatory, antibacterial, blood sugar and fat reduction, and organ protection. They also enhance immune function, earning them the title of “soft gold.”
JIAO and colleagues studied the effect of pre-soaking theaflavins on the quality changes in semi-dried large yellow croaker fillets. The results showed that theaflavin treatment improved the texture and color stability of the fillets during storage at room temperature and refrigeration, maintaining the protein and fat properties.
ZHUANG Qianqian and others selected theaflavins and lipophilic tea polyphenols as natural food additives to be added to beef sticks. Through acid value, peroxide value, color value measurements, and sensory evaluations, it was found that at 20°C and 50% RH, the shelf life of the product could be extended by 80 days. This fully proves that theaflavins and lipophilic tea polyphenols can prevent food oxidation, improve color, and serve as a nutritional ingredient, safeguarding health.
GAO and colleagues evaluated the effects of theaflavins, tea polyphenols, and vitamin C on nitrite residue, color, antioxidant capacity, and N-nitrosamine inhibition in pickled sausages. The results showed that adding theaflavins, tea polyphenols, and vitamin C together with NaNO2 significantly improved the a* value, nitroso pigment content, and DPPH free radical scavenging rate, and effectively reduced residual nitrite, MetMb, and total N-nitrosamines, with the theaflavin group showing the most significant effects (p < 0.05). Theaflavins and tea polyphenols help maintain sausage color and improve safety.
WANG and colleagues studied the interaction between theaflavins and milk lactoferrin, observing how theaflavins affected the structure and function of milk lactoferrin. In in vitro simulations, they found that adding theaflavins effectively enhanced the ability of lactoferrin to bind iron, reduced its allergenicity, and decreased its digestibility in the intestines, offering potential for developing new functional dairy drinks.
The antioxidant activity of theaflavins is one of their most well-known effects. The multiple hydroxyl groups in the theaflavin molecular structure provide strong antioxidant capacity. These hydroxyl groups can donate protons, directly neutralize free radicals, and chelate metal ions to prevent the oxidation of low-density lipoproteins (LDL), exerting antioxidant effects in the body. Studies show that the antioxidant activity of theaflavins is superior to that of epigallocatechin gallate (EGCG) in green tea, effectively scavenging hydroxyl radicals, DPPH free radicals, and protecting cells from oxidative damage.
Cardiovascular Diseases
Cardiovascular diseases are one of the major global health problems, and theaflavins have shown great potential in preventing and treating these diseases. Theaflavins can reduce blood viscosity, improve microcirculation, and lower the risk of cardiovascular diseases by improving erythrocyte deformability, regulating erythrocyte aggregation, and platelet adhesion and aggregation. Additionally, theaflavins can inhibit the inflammatory response in vascular endothelial cells and reduce the formation of atherosclerosis.
Inflammation is a key factor in many chronic diseases, and the anti-inflammatory activity of theaflavins offers new strategies for treating inflammation-related diseases. Studies have shown that theaflavins can inhibit the production of inflammatory cytokines and reduce the infiltration of inflammatory cells, thus exerting effects in inflammatory diseases. Moreover, theaflavins inhibit the NF-κB signaling pathway, reducing the expression of inflammation-related genes and exerting anti-inflammatory effects.
Theaflavins also exhibit significant antibacterial and antiviral activities, inhibiting the growth of various bacteria and viruses, including resistance bacteria and stubborn viruses like HIV. Studies show that theaflavins can directly act on viral particles, suppressing the replication and spread of viruses, demonstrating potential as an antiviral drug.
Anti-Tumor Effects
The theaflavins’ mechanisms in anti-tumor activity are diverse, including scavenging free radicals, inhibiting cell mutations, suppressing cancer cell transcription, and promoting cancer cell apoptosis. Research has shown that theaflavins can induce apoptosis in tumor cells, inhibit the proliferation and spread of tumor cells, and inhibit a variety of cancer cell lines. Theaflavins’ anti-tumor activity provides scientific evidence for their application in cancer prevention and treatment.
Neurological Benefits
Theaflavins also show potential benefits in regulating neurological functions. Studies have shown that theaflavins can protect nerve cells through antioxidant and anti-apoptotic activities, reducing the occurrence of neurodegenerative diseases.
Anti-Diabetes Effects
Diabetes is a global public health issue, and theaflavins have demonstrated potential in anti-diabetes research. Studies show that theaflavins can delay diabetic glomerular hypertrophy and glomerulosclerosis by regulating the p38 MAPK signaling pathway and reducing the synthesis of extracellular matrix.
Weight Loss and Fat Reduction
The weight loss and fat reduction effects of theaflavins are mainly due to their inhibition of squalene synthase production, reducing the activity of fatty acid synthase (FAS), and inhibiting cholesterol absorption in the intestine, effectively lowering plasma cholesterol levels. Through research on the effects of functional components such as theaflavins, theaflavin, and theaflavin-related pigments on the gut microbiota of rats fed a high-fat diet, it was found that theaflavins effectively inhibit rat weight gain and Lee’s index increase, regulate blood lipids, reduce body fat accumulation, and improve the species richness and diversity of gut microbiota, thereby achieving fat reduction and weight loss.
Other Benefits
In addition to the above effects, theaflavins also exhibit anti-anxiety, memory improvement, and anti-allergy properties.
As an important physiological active component in tea, the various effects of theaflavins provide new strategies for the prevention and treatment of many diseases. With the continuous development of science and technology, more potential benefits and mechanisms of theaflavins will be further revealed, and their applications in medicine, food, and other fields will become even broader. In the future, the research and application of theaflavins will become an important direction for tea science research, bringing more benefits to human health.
Small Tip:
As tea flavonoids like theaflavins gain increasing recognition for their potential health benefits, incorporating tea-based ingredients into everyday diets could contribute to better overall wellness. Whether it’s through antioxidant-rich beverages, supplements, or functional foods, tea and its active compounds are paving the way for natural health solutions.
