A major scientific review uncovers how a simple cup of brewed tea can deliver real health gains, from heart protection to sharper cognition. However, it also warns consumers about the risks hiding in supplements and processed tea drinks.

Study: Beneficial health effects and possible health concerns of tea consumption: a review. Image credit: Pixel-Shot/Shutterstock.com

In a recent study published in Beverage Plant Research, researchers examined the health effects of tea consumption. They concluded that tea is broadly safe and beneficial, particularly when consumed as traditional brewed tea. Green tea exhibits the most consistent benefits, although black and other teas also offer advantages.

A globally popular beverage

Tea made from Camellia sinensis is among the most widely consumed beverages worldwide, with black and green teas accounting for the majority of production. Modern research has focused on identifying the active compounds that contribute to these effects, particularly tea polyphenols, mainly catechins in green tea and theaflavins and thearubigins in black tea.

Green tea is minimally fermented, preserving high levels of catechins, while black tea undergoes extensive oxidation that converts catechins into complex polyphenols. Caffeine and the amino acid theanine also contribute to tea’s physiological actions.

Large cohort studies have linked tea consumption to lower cardiovascular mortality, a reduced risk of certain cancers, and a decreased incidence of type 2 diabetes. Laboratory studies provide mechanisms related to antioxidant activity, improved lipid metabolism, and modulation of signaling pathways. However, translating findings from cell and animal studies to humans is challenging due to differences in bioavailability, dosage, and physiology.

Heart disease, cancer, and mortality

The strongest and most consistent evidence links tea consumption, particularly green tea, to a reduced risk of cardiovascular disease (CVD). Large cohort studies demonstrate that drinking around 1.5 to 3 cups per day lowers CVD and all-cause mortality, with cardiovascular benefits remaining significant even at higher intakes. However, diminishing returns are observed for overall mortality.

Benefits observed in Japan, China, and the UK suggest that both green and black tea contribute to improved vascular health. Mechanistic studies suggest that polyphenols reduce low-density lipoprotein (LDL) cholesterol, enhance endothelial function, lower blood pressure, and exhibit antioxidant and anti-inflammatory effects.

Evidence for cancer prevention is more mixed: while animal studies are robust, human findings vary by cancer type and population. Still, meta-analyses support risk reductions for oral, lung (in women), and colon cancers with regular green tea intake.

Weight management and type 2 diabetes

Green tea and catechin-rich preparations show modest but consistent effects on reducing body weight and fat mass, particularly in overweight individuals. Trials report reductions in LDL cholesterol and oxidative stress after several weeks of consumption.

Cohort studies generally indicate a lower risk of type 2 diabetes with higher tea intake. Yet, contradictory findings exist, most notably from the Shanghai Women’s and Men’s Health Studies, which reported an increased risk of diabetes.

Randomized trials in diabetic patients have not shown improvements in glucose or insulin measures, leaving uncertainty about tea’s role in glycemic control.

Neuroprotection and muscle health during aging

Epidemiological evidence from China and Japan suggests that habitual tea drinking is associated with reduced cognitive decline, improved cognitive performance, and lower biomarkers linked to Alzheimer’s disease. Meta-analyses also find a clear protective association, with the strongest effects observed in adults aged 50 to 69 years. Theanine, a unique component of tea, may contribute to stress-reduction and neurocalming effects, as well as its ability to cross the blood–brain barrier.

Research indicates that catechin-rich extracts can help maintain or increase muscle mass and strength, especially in older adults or individuals with sarcopenia. Human trials have shown improved grip strength and muscle function after supplementation, while animal studies have demonstrated protective effects against disuse-induced muscle loss.

Inflammation, immunity, and disease protection

Green tea consumption is linked to lower uric acid levels, with stronger associations observed in men. Small experimental studies have shown an enhanced excretion of uric acid following the intake of tea or catechins. Tea polyphenols also reduce inflammatory markers and improve markers of oxidative stress, including in individuals with hypertension or chronic kidney disease.

Tea catechins inhibit a wide range of bacteria and viruses. In the oral cavity, catechins can reduce the growth of cariogenic bacteria and improve oral health. Some demonstrate antiviral effects against hepatitis viruses, influenza, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and human papillomavirus (HPV), mainly by blocking viral entry processes. However, most antiviral studies are in vitro and cannot be directly extrapolated to humans.

Different types of tea and tea-based beverages

Although green tea carries the strongest evidence base, Oolong, white, dark, and yellow teas also show potential benefits. Animal studies comparing teas made from the same leaf batches suggest Oolong tea may outperform others in weight control, while white tea may be most effective for lipid reduction. Still, these findings cannot be reliably generalized to humans.

Bottled or bubble teas pose health concerns due to the addition of sugars, sweeteners, and preservatives, which may counteract their natural benefits. Processing and storage also reduce catechin content compared with traditional brewing.

Conclusions

The review highlights strong human evidence for cardiovascular and metabolic benefits of tea, with additional promising effects on cognition, muscle health, inflammation, and microbial activity. A major strength is its reliance on large cohort data supplemented by mechanistic insights.

However, inconsistent findings, especially for diabetes and cancer, and limited human research on non-green teas remain significant limitations. Results from animal and in vitro studies cannot be directly extrapolated to humans.

Despite these gaps, the overall conclusion is that tea is a safe, health-promoting beverage when consumed traditionally. However, high-dose supplements and low-quality commercial products present potential risks that consumers should be aware of. Further high-quality human research is needed across diverse tea types and health outcomes.

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The review confirms that tea, particularly green tea, plays a crucial role in preventing cardiovascular diseases (CVDs), obesity, diabetes, and certain types of cancer. Tea’s neuroprotective effects, ability to reduce muscle loss in seniors, and its anti-inflammatory and antimicrobial activities further highlight its potential health-promoting properties. However, the study also identifies potential health concerns, particularly with bottled and bubble teas, which may contain harmful additives like artificial sweeteners and preservatives.

Tea, made from the leaves of Camellia sinensis, has been consumed globally for centuries, initially for its medicinal properties and later as a popular beverage. It has long been recognized for its rich polyphenolic content, particularly catechins, which contribute to its health benefits. This review aims to provide a detailed analysis of tea’s impact on various health conditions, supported by both experimental and human studies. Despite extensive studies on green tea, there is limited information on the effects of other tea types, such as black, oolong, and white tea, especially concerning their comparative health benefits. Furthermore, the health concerns raised by the presence of additives and contaminants in some commercial tea beverages are addressed.

A study (DOI: 10.48130/bpr-0025-0036) published in Beverage Plant Research on 13 November 2025 by Mingchuan Yang & Li Zhou’s team, Tea Research Institute, Chinese Academy of Agricultural Sciences, underlines the need for further research to better understand tea’s health benefits and risks.

The review delves into various health conditions linked to tea consumption. Green tea is highlighted for its cardiovascular protective effects, reducing blood pressure and improving cholesterol levels. Multiple cohort studies also show that regular tea consumption can lower the risk of all-cause mortality, CVDs, and certain cancers. Furthermore, tea’s role in weight management and its potential in controlling diabetes are discussed, with evidence suggesting that green tea catechins can aid in weight reduction and improve metabolic parameters in obese individuals. Notably, tea also shows promise in neuroprotection and muscle mass preservation. Studies indicate that regular tea drinkers experience a reduced prevalence of cognitive decline and Alzheimer’s disease biomarkers, particularly in older adults. Similarly, tea catechins may prevent muscle loss in seniors, contributing to better physical performance and muscle strength. However, while tea has numerous benefits, commercial tea products such as bottled or bubble tea, often contain sugar, artificial sweeteners, and preservatives, which may reduce or negate the health benefits. Additionally, concerns regarding pesticide residues, heavy metals, and microplastics in tea have been raised. These contaminants, though not posing significant health risks in typical consumption, remain a concern for long-term heavy tea drinkers. Moreover, the review addresses the issue of nutrient absorption interference, specifically with non-heme iron and calcium, potentially affecting people on vegetarian diets or those with specific nutritional needs.

The health benefits of tea are clear, but its consumption in processed forms like bottled tea and bubble tea should be moderated due to added sugars and preservatives. The findings from this review suggest that moderate consumption of traditional, freshly brewed tea can be beneficial, especially for preventing cardiovascular diseases, diabetes, and cancer. Future studies focusing on the long-term health effects of different tea types and the impact of contaminants will help refine our understanding of tea’s health benefits and risks.