Coffee has become a daily essential for many people to stay alert. Beyond its energizing effects, extensive research has shown that coffee may help reduce the risk of death and certain types of cancer. However, recent studies warn that poor drinking habits — like adding sugar — can turn this health-promoting beverage into a potential cancer risk.
Sugar makes a big difference
Many people prefer flavored coffee with syrups or juices instead of plain black or Americano coffee. A 2025 study published in the Journal of Nutrition revealed a strong link between coffee and cancer risk. Drinking more than 2 cups (approximately 250 ml each) of unprocessed coffee daily reduced the risk of cancer by 5 percent and overall mortality by 11 percent. Drinking more than 2 cups of sweetened coffee daily increased cancer risk by 6 percent and mortality risk by 25 percent.
This difference is attributed to the presence of antioxidants, such as polyphenols, in unsweetened coffee and tea, which help reduce chronic inflammation and cellular damage. In contrast, high sugar intake spikes blood glucose, promotes insulin resistance and oxidative stress, and activates pathways that encourage cancer.
The best time to drink coffee
In 2025, Harvard University and other institutions introduced the concept of a “coffee drinking time window” in the European Heart Journal. They studied three groups: those who drank coffee only in the morning, those who drank it throughout the day, and those who didn’t drink coffee. The findings showed:
- Compared to non-coffee drinkers, individuals who drank coffee only in the morning had a 16 percent lower overall mortality rate and a 31 percent lower cardiovascular mortality rate.
- Those who drank coffee throughout the day saw no reduction in mortality risk.
- Drinking 2 to 3 cups of coffee daily was found to be the optimal amount for reducing the risk of death.
- To get the most health benefits from coffee, avoid sugar and drink it at the right time.
Five tips for healthy coffee drinking
- Choose black or Americano: Studies show unsweetened coffee is linked to health benefits, while sugary coffee increases risks. If it’s too bitter, add a small amount of milk, such as oat milk or soy milk, to balance the flavor.
- Drink during the “golden window”: Morning coffee consumption is associated with a lower risk of cardiovascular and overall mortality. Drinking too late may affect sleep.
- Stick to moderate amounts: Research suggests 2-3 cups per day (about 400-500 ml) is safe and beneficial.
- Avoid overly hot drinks: The International Agency for Research on Cancer (IARC) classifies drinks over 65°C as probable carcinogens due to potential esophageal damage.
- Coffee isn’t a cure-all: Coffee’s benefits are most effectively realized when consumed as part of a healthy lifestyle, which includes a balanced diet, regular exercise, and sufficient sleep.
Translated by Cecilia and edited by Amanda
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