Unsweetened tea and longevity: evidence from a prospective cohort study

More than 2 billion people worldwide drink tea, and a number of observational studies have linked moderate consumption with lower mortality. But it has been unclear whether the potential benefit persists when tea is sweetened with sugar or sugar substitutes. A new study in Frontiers in Nutrition examines this question using data from the UK Biobank.

Research methods

A prospective analysis was conducted of 195,361 UK Biobank participants who completed ≥1 online 24-hour food survey (up to 5 repetitions). Tea was classified as: no sweeteners, with sugar, with artificial sweeteners; serving size — ~250 ml. Risks of total, cancer, and cardiovascular mortality were estimated using Cox proportional hazards models and RCS curves (nonlinearity check), taking into account a wide range of covariates (age, gender, deprivation index, education, smoking status and duration, BMI, physical activity, comorbidities and medications, as well as diet: energy, sugar, fruits/vegetables, meat, alcohol, coffee, milk, etc.). The median follow-up was 13.6 years. Additionally, stratification was performed by the genetic index of caffeine metabolism.

Key Results

• For unsweetened tea, a U-shaped association with the risk of death was found: minimum at 3.5–4.5 servings/day. Compared with non-drinkers: total mortality HR 0.80 (0.75–0.86); cancer HR 0.86 (0.77–0.97); CVD HR 0.73 (0.60–0.89).
• Sugared tea: Associations were inconsistent and statistically inconclusive across consumption categories for all-cause, cancer, and CV mortality. Artificially sweetened tea also showed no significant associations.
• Caffeine metabolism genes did not modify the observed associations.

Interpretation and clinical conclusions

The results are consistent with the idea that the potential benefits of tea are concentrated in unsweetened beverages, while sugar and possibly substitutes may moderate these effects. However, this is an observational study: causal inferences cannot be made, and residual confounding is possible (e.g., diet tea consumers were older, smoked more often, had more diseases and treatments at baseline). The authors’ practical conclusion: all other things being equal, it is better to drink tea without sweeteners if the goal is health and longevity.

Authors' comments

• "Unsweetened tea is associated with a significantly lower risk of overall, cancer, and cardiovascular mortality."
• "No consistent or statistically significant associations were found for tea with sugar or artificial sweeteners."
• "To maximize the health and longevity benefits, it is advisable to drink tea without added sweeteners."
• "Moderate consumption of unsweetened tea (approximately 3.5–4.5 servings per day) is associated with a minimal risk of all-cause mortality."
• "Our work is the first study to examine these associations in a large prospective cohort with long-term follow-up."
• "The results obtained should be interpreted with caution."

The authors emphasize that unsweetened tea is associated with a lower risk of overall, cancer, and CV mortality, while no convincing links were found for sweetened options; the hypothesis of "erasing" the benefits with sugar/sweeteners requires confirmation in future studies. The recommendation based on current data is to give preference to tea without additives.