Does adding sugar to tea take away the benefits? The surprising truth

November 30, 2025 •

3 min read

A recent UK Biobank study found that unsweetened tea consumption is linked to a reduced risk of all-cause mortality, suggesting that adding sugar to tea may diminish its health benefits. This discovery challenges the common practice of sweetening tea for flavor, prompting a closer look at what happens when sugar is introduced to this antioxidant-rich beverage.

Quick Summary

Adding sugar introduces empty calories and can diminish some of tea's natural benefits, but the impact is dose-dependent. Its effect on antioxidants is complex and appears to vary with tea type and amount added.

Key Points

Antioxidants Negatively Affected: Sugar can interfere with the body's absorption of beneficial tea antioxidants like polyphenols, especially in green tea.
Empty Calories and Weight Gain: Adding sugar introduces unnecessary calories that contribute to weight gain, diminishing the zero-calorie benefit of plain tea.
Blood Sugar Regulation is Hampered: Consuming sweetened tea can lead to blood sugar spikes and crashes, potentially harming insulin sensitivity over time.
Dental Health at Risk: The sugar in tea feeds bacteria that cause tooth decay and cavities, negating tea's natural antibacterial properties.
Heart Health Concerns Rise: Excessive sugar intake from sweetened beverages can increase the risk of heart disease by promoting inflammation and weight gain.
Unsweetened Tea is Superior for Health: Studies show that unsweetened tea offers greater protective benefits against conditions like heart disease, diabetes, and overall mortality.

The Core Benefits of Unsweetened Tea

Tea, in its pure form, is a powerhouse of beneficial compounds, primarily polyphenols and flavonoids, which act as potent antioxidants. These compounds are credited with many of tea's most celebrated health advantages, including supporting heart health, lowering cholesterol, and improving insulin sensitivity. When consumed without additives, tea is a low-calorie beverage that contributes to hydration and wellness. Its benefits, which can include boosting focus and providing sustained energy due to the combination of caffeine and L-theanine, are best realized when sugar does not interfere.

The Health Costs of Excessive Sugar

While a touch of sweetness might be a personal preference, excessive and regular sugar consumption carries significant health risks. Every teaspoon of sugar adds approximately 16 empty calories, which can quickly accumulate for habitual tea drinkers. Beyond the calorie count, high sugar intake is linked to:

Blood Sugar Spikes: Rapid increases in blood sugar levels can lead to energy crashes and, over time, insulin resistance, a precursor to type 2 diabetes.
Weight Gain: Liquid calories are less satiating, making it easy to consume more than intended, a major contributor to weight gain and obesity.
Increased Inflammation: Excessive sugar can cause chronic inflammation in the body, which is a risk factor for heart disease.
Poor Oral Health: Sugar feeds harmful bacteria in the mouth, leading to plaque formation, tooth decay, and cavities.

Sugar's Impact on Tea's Antioxidants

One of the most debated aspects is whether sugar chemically interacts with tea's antioxidants. The research is not entirely conclusive and varies by tea type.

Possible Negative Interactions:

Some studies indicate that sugar might interfere with the absorption of polyphenols and catechins in the intestines. The mechanism is thought to involve competition for absorption pathways or condensation reactions between sugar molecules and phenolic compounds, potentially reducing the antioxidant activity, especially in green tea.

Possible Positive Interactions (in some cases):

Interestingly, other studies on black tea have suggested that adding sugar might not significantly decrease, and in some cases might even stabilize, the antioxidant activity. This is believed to occur through different chemical interactions within black tea's unique composition of theaflavins and thearubigins. However, this is heavily debated and likely does not outweigh the negative systemic effects of added sugar.

Alternatives to Sweetened Tea

For those seeking a healthier cup without sacrificing flavor, several alternatives offer a similar soothing experience without the downsides of refined sugar:

Honey and Maple Syrup: Though still sugars, they have a slightly lower glycemic index and contain some trace nutrients compared to white sugar. Use sparingly.
Natural Sweeteners: Stevia and monk fruit are calorie-free options that provide sweetness without impacting blood sugar levels.
Natural Flavor Enhancers: A squeeze of lemon, a dash of cinnamon, fresh ginger, or a few mint leaves can add complex flavor profiles and potentially enhance health benefits.
High-Quality Loose-Leaf Tea: Better quality teas are often less bitter and naturally sweeter, allowing you to appreciate the full flavor without additives.

A Comparison of Sweetened vs. Unsweetened Tea


Feature	Unsweetened Tea	Sweetened Tea
Calories	Virtually zero	Adds empty calories (approx. 16 per tsp)
Antioxidant Absorption	Uninterrupted absorption of polyphenols and flavonoids	Potential interference with absorption, especially with green tea
Blood Sugar Impact	Does not spike blood sugar levels; may help regulate them	Causes blood sugar spikes and contributes to insulin resistance
Dental Health	Beneficial; contains antibacterial properties	Detrimental; promotes tooth decay and cavities
Cardiovascular Health	Reduces risk of heart disease and stroke	Increases risk due to weight gain and potential inflammation
Focus and Energy	Provides sustained energy without the sugar crash	Causes energy peaks followed by crashes

Conclusion: The Impact of Adding Sugar

While adding a small, occasional amount of sugar may not completely eliminate all the benefits of tea, regular or excessive consumption fundamentally alters the beverage's health profile. The core antioxidants in tea, while still present, can be overshadowed by the negative systemic effects of sugar, such as increased calories, blood sugar fluctuations, and weight gain. For optimal health outcomes, including heart health and diabetes prevention, enjoying tea unsweetened or with natural alternatives is the better choice. The ultimate decision rests with individual preference and health goals, but the scientific evidence suggests a clear difference between a healthy brew and a sugary treat.

For a detailed analysis on how sweetened tea affects mortality, a large prospective cohort study in the UK Biobank provides compelling evidence.

Frequently Asked Questions

While a small amount of sugar added occasionally may not completely negate all benefits, regular and excessive consumption introduces empty calories and can interfere with the body's ability to absorb some antioxidants, reducing the overall health advantage.

Research findings are mixed. Some studies suggest adding sugar significantly decreases green tea's antioxidant activity, while other, heavily debated studies suggest it might not have the same negative effect on black tea's antioxidants. However, the overall health risks of excess sugar remain regardless of the tea type.

Healthy alternatives include using natural, calorie-free sweeteners like stevia or monk fruit, or adding natural flavor enhancers such as a squeeze of lemon, cinnamon, or fresh mint.

Sugar promotes tooth decay by feeding bacteria in the mouth that produce acid, which in turn erodes tooth enamel. Sipping sugary tea over an extended period is particularly harmful, as it maintains an acidic state in the mouth.

Yes, regularly adding sugar to tea contributes extra calories to your diet. Since liquid calories don't provide the same feeling of fullness as solid food, it can be easy to consume more calories than you burn, leading to weight gain.

While honey contains trace amounts of vitamins and minerals and has a slightly lower glycemic index than refined sugar, it is still a sugar. Both should be used in moderation, but honey offers a slight nutritional edge and contains antimicrobial properties.

For individuals managing diabetes, it is best to avoid adding sugar to tea. Sugar causes blood sugar levels to spike, which can worsen diabetes control over time. Opt for unsweetened tea or consult a healthcare professional for suitable alternatives.