Tea may offer powerful health benefits, but how it is prepared and consumed matters.
Across human cohort studies and clinical trials, tea
drinking shows its most consistent links to better heart and metabolic health,
including lower risks of cardiovascular disease (CVD) and related
problems like obesity and type 2 diabetes — with hints of protection against
some cancers as well.
The authors also point to early signs that tea may be tied
to slower cognitive decline, less age-related muscle loss, and
anti-inflammatory and antimicrobial effects. Those areas are promising, they
note, but still need stronger long-term human trials.
How much you drink seems to matter, too. In a meta-analysis
of 38 prospective cohort data sets, “moderate” intake tracked with lower
all-cause, CVD, and cancer mortality. For CVD mortality, the benefit signal
appeared to level off around ~1.5–3 cups per day, while all-cause mortality
showed its strongest association at ~2 cups per day.
Tea Types, Composition, and Study Scope
At the same time, the review notes that not all tea products
are created equal. Bottled teas and bubble teas can include additives such as
artificial sweeteners and preservatives, which may introduce health concerns
that do not apply in the same way to brewed tea.
Tea is made from the leaves of Camellia sinensis and
has been consumed worldwide for centuries. It was first valued largely for
medicinal purposes before becoming a widely enjoyed beverage. Scientists have
long been interested in tea because it contains high levels of polyphenols,
particularly catechins, which are thought to play a major role in many of its
reported benefits.
This review, published in Beverage Plant Research,
brings together evidence from laboratory research and human studies to examine
how tea relates to a wide range of health outcomes. While green tea has been
studied extensively, the authors emphasize that far less is known about black,
oolong, and white tea, especially when it comes to comparing their health
effects. The review also considers concerns raised by additives and possible
contaminants found in some commercial tea drinks.
Cardiovascular and mortality links
In the review, green tea stands out for cardiovascular
protection. Human studies summarized by the authors link tea intake to modest
reductions in blood pressure and improvements in blood lipids, including lower
LDL cholesterol.
Large cohort studies also associate regular tea drinking
with reduced all-cause mortality and lower deaths from CVD, with the most
consistent signal appearing in populations where green tea is the dominant
type.
Weight and metabolic health
For weight control and cardiometabolic markers, the review
emphasizes that results are strongest in overweight/obese groups and depend on
dose and study design. As examples:
- In
people with obesity and metabolic syndrome, drinking ~4 cups/day of green
tea for 8 weeks was reported to decrease body weight, lower LDL
cholesterol, and reduce oxidative stress markers in at least one
randomized trial highlighted in the review.
- In
another trial in overweight adults, ~600–900 mg/day of tea catechins (with
<200 mg/day caffeine) for ~90 days was associated with reduced body
fat.
On diabetes specifically, the review notes that many cohort
studies link higher tea intake (often ~3–4+ cups/day) to lower type 2 diabetes
risk, but results are not uniform.
Some large population data sets have shown the opposite
pattern, and in several trials of people already diagnosed with type 2
diabetes, green tea extracts did not consistently improve HbA1c, glucose,
or insulin.
Cancer
The authors describe cancer findings as strong in animal
research but mixed in human studies, likely because cancer risk varies by site,
genetics, and environment. Still, meta-analyses cited in the review report
lower risk signals for certain cancers, including:
- Oral
cancer (reported relative risk around 0.798 for frequent green tea
consumption)
- Lung
cancer in women (reported RR around 0.78)
- Colon
cancer (reported OR around 0.82)
Brain health and cognitive aging
The review highlights observational evidence that frequent
tea consumption is associated with lower prevalence of cognitive impairment.
One meta-analysis summarized in the paper combined 18
studies (totaling ~58,929 participants) and found green tea intake was linked
to lower odds of cognitive impairment, with the strongest association seen in
adults aged ~50–69.
The authors also note that tea contains theanine, an
amino acid that can cross the blood–brain barrier and has been linked
in studies to stress-reducing and anti-anxiety effects, which could indirectly
support cognitive health.
Muscle preservation in older adults
The review also points to early clinical evidence that tea
polyphenols may help counter sarcopenia (age-related muscle loss).
One randomized controlled trial cited reported that ~600
mg/day of an epicatechin-enriched green tea extract for 12 weeks improved
measures such as handgrip strength and attenuated muscle loss. Other studies
discussed suggest tea catechins may work best when paired with resistance
exercise and adequate protein/amino acid intake.
Inflammation and immune/antimicrobial activity
On inflammation, the review includes trials where catechins
were associated with reduced inflammatory biomarkers. For example, in an RCT
involving obese hypertensive participants, ~379 mg/day green tea extract for 3
months was associated with reductions in TNF-α (~14.5%) and C-reactive protein
(~26.4%), alongside improved insulin-resistance–related measures.
Tea’s antimicrobial effects are described as particularly
plausible in the mouth and upper airway because tea compounds directly contact
oral microbes. The authors cite evidence that catechins can inhibit
cavity-causing bacteria (such as Streptococcus mutans), supporting interest in
tea-based rinses for oral health. They also describe mostly lab-based antiviral
findings (including work on influenza and coronaviruses) and note that human
evidence remains limited, though small studies (such as catechin gargling in
older adults) have reported lower infection rates and warrant larger
replication.
Potential Risks and Commercial Tea Products
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.
Reference: “Beneficial health effects and possible health
concerns of tea consumption: a review” by Mingchuan Yang, Li Zhou, Zhipeng Kan,
Zhoupin Fu, Xiangchun Zhang and Chung S. Yang, 13 November 2025, Beverage
Plant Research.
DOI: 10.48130/bpr-0025-0036
