Putting sugar in coffee has varied effects: study

Amidst increasing rates of caffeine consumption and skyrocketing occurrences of obesity and type 2 diabetes, a research team from the Auckland University in Technology in New Zealand set out to see if sugar makes a difference in how the body responds to coffee.

In the small study, 12 participants were given coffee that contained 1.33 milligrams of caffeine per kilogram of their respective body weight on an empty stomach.

On a separate day, they were given the same amount of coffee with 0.4 grams of sugar per kilogram of body weight and on a third day they were given sugar only.

A half hour before and after each coffee consumption trial, researchers measured their respiratory gas exchange by the breath and took their pulse.

They analyzed participants' responses using data visualization techniques and found that drinking coffee without sugar slowed the heart rate of eight participants but didn't change anything for the remaining four.

Consuming sugar alone increased the heart rate for eight participants and didn't affect the heart rates of the remaining four.

Drinking coffee with sugar was the most varied response, for heart rate increased for one participant and decreased for five participants, while the remaining six participants saw no change.

Carbon dioxide production either increased or didn't change during all three treatments.

Due to the varied physiological responses in their small study, which was published in the Journal of Caffeine Research, the team says an investigation of habitual consumption of caffeine and sugar is necessary.