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A longitudinal study found no association between sweetening coffee or tea and a heightened risk of diabetes and all-cause mortality. Image credit: Trent Lanz/Stocksy.
  • Researchers from Denmark and the Netherlands analyzed data from the longitudinal Copenhagen Male Study to see whether adding sugar to coffee or tea could impact health outcomes.
  • They looked at the incidence of diabetes, deaths caused by heart disease or cancer, and all-cause mortality.
  • The researchers found that adding sugar to coffee or tea did not pose additional health risks to a significant extent.

An excess of sugar in a person’s diet can lead to health issues, including tooth decay, obesity, and heart disease.

The American Heart Association recommends no more than 9 teaspoons of added sugar for men and 6 teaspoons of added sugar for women per day, but many people often exceed that.

With one can of soda containing more than the recommended maximum daily sugar intake for both men and women, it is easy to exceed those recommendations.

Recently, a team of researchers from institutions in Denmark, the Netherlands, and the United Kingdom, wondered if adding sugar to one’s daily cup of coffee or tea is as harmful to health as commonly assumed.

Analyzing data from the Copenhagen Male Study, the scientists did not find an increased risk of all-cause mortality, diabetes, or deaths attributed to cancer or heart disease in men who added sugar to coffee or tea.

The study findings appear in PLOS ONE.

The Copenhagen Male Study began during the 1970s and focused on Danish men ages 40-59 when the study began.

Part of the initial workup included assessing the men’s heart and lung health, plus getting the men to complete questionnaires about their lifestyles.

During one of the follow-up appointments, doctors measured the participants’ blood pressure, height, and weight. One of the questionnaires the participants completed at this time asked about their coffee and tea intake, and whether they added sugar to these drinks.

Of the data available for the Copenhagen Male Study, the researchers in the new study analyzed data from 2,923 men who met the parameters for inclusion.

All men included had no prior history of heart disease, cancer, or type 2 diabetes when they joined the study. Additionally, the researchers only included men who indicated drinking coffee or tea.

The researchers had access to the medical records, either for living men or those deceased, for 99% of the participants.

When the scientists began their analysis, they divided the participants into the sugar and non-sugar groups and calculated the risk for all-cause mortality, cancer deaths, heart disease deaths, and type 2 diabetes for each group.

The researchers did not ask participants how much sugar they added to their coffee or tea, but assumed that it was a small amount. Overall, they did not find a significant risk for health issues in people in the sugar group versus the “no sugar” group.

The sugar group’s death rate was 89.9%, and the “no sugar” group’s death rate was 87.5%. Over time, there was no statistically significant association between the use of sugar in coffee and tea and all-cause mortality.

In terms of heart disease mortality, the sugar group also had a slightly higher — but comparable — rate. The sugar group’s rate was 38.2% while the “no sugar” group’s rate was 35.3%.

When the researchers looked at the incidence of type 2 diabetes, they noted the “no sugar” group had a slightly higher rate of developing the disease than the sugar group. Again, there was no statistical difference for the association between the two groups over time.

The sugar group 8.1% rate of developing diabetes was comparable to the “no sugar” group, which had a 9.9% rate.

“Important findings of this study were that, when correcting for important confounders, there was no statistically significant association between the use of sugar in coffee and tea and all-cause mortality, cardiovascular mortality, cancer mortality or incident diabetes mellitus,” write the authors.

Dr. Sarah Stombaugh, a board-certified family medicine physician and a diplomate of the American Board of Obesity Medicine, not involved in this research, spoke with Medical News Today about the study.

“It is interesting to see that this study did not draw a correlation between use of sugar in coffee and tea and mortality in heart disease, cancer, or type 2 diabetes,” said Dr. Stombaugh.

“The good news is this study demonstrates that adding small amounts of sugar to our diet can be done without serious risk,” she commented.

Dr. Stombaugh pointed out the study focuses on adding sugar to tea or coffee made at home and that the sugar content of these homemade beverages can drastically differ from those purchased in restaurants or coffee shops.

“When someone adds sugar at home, they are likely to add less sugar than you would find in flavored coffee drinks at your favorite coffee shop,” she noted.

“There are 4 grams in one teaspoon of sugar; most people will add a teaspoon or two of table sugar to their coffee or tea,“ Dr. Stombaugh explained. “On the other hand, many flavored coffee drinks have upwards of 30 grams of sugar, with a grande Starbucks pumpkin spice latte containing 50 grams of sugar.”

Registered dietitian nutritionist Kelsey Costa also spoke with MNT about the study and also emphasized the importance of the study analyzing tea and coffee made at home. She was not involved in the original research.

“It’s essential to clarify the amount of sugar typically added to homemade tea or coffee — around 5 grams — is considerably less than the sugar content in most commercially prepared beverages. The study focuses on traditional tea and filtered black coffee, which typically has minimal sugar added, thereby excluding the more significant health impacts of modern, sweeter drink variants.”

– Kelsey Costa

While Costa found the study results interesting, she noted one particular weak point.

“The study offers robust findings due to its 32-year duration, large sample size, and almost complete follow-up,” noted Costa. “However, it is limited by its reliance on self-reported data and the assumption of stable intake over time, which may not accurately reflect reality.”

She also pointed out the study findings, which were based on Danish men, may not apply to other populations.

“The possibility of reduced sugar use over time, changing socioeconomic status, and the effect of sugar in tea or coffee on other dietary choices need further exploration,” she added.

It is important to keep an eye on nutrition facts when consuming food or beverages. Oftentimes, there can be added sugar to consumables that people might not expect.

The Centers for Disease Control and Prevention (CDC) recommend that added sugar should make up less than 10% of a person’s caloric intake and that the amounts currently consumed are putting people’s health at risk.

While avoiding added sugar is ideal, there are some sources of sugar that are healthier than others.

If someone wants to satisfy their sweet tooth, they should focus on fruits. While the sugar in fruits can can raise blood sugar levels, they can nevertheless also bring nutritional benefits not associated with sugary drinks or snacks.