MADRID, 15 Mar. (EUROPA PRESS) -
A high level of caffeine in the blood could curb the amount of body fat a person has and their risk of type 2 diabetes, suggests research published in the open access journal 'BMJ Medicine'.
In light of their findings, the researchers say the potential role of calorie-free caffeinated beverages in reducing the risks of obesity and type 2 diabetes is probably worth exploring now.
Previously published research indicates that drinking 3 to 5 cups of coffee, a rich source of caffeine, daily is associated with a lower risk of type 2 diabetes and cardiovascular disease, the researchers note. An average cup of coffee contains between 70 and 150 mg of caffeine.
But most of the research published to date concerns observational studies, which cannot reliably establish causal effects, due to the other potentially influential factors involved, the researchers note.
Furthermore, it is difficult to separate the specific effects of caffeine from those of other compounds present in caffeinated beverages and foods, they add.
To try to overcome these problems, the researchers used Mendelian randomization to find out what effect higher levels of caffeine in the blood have on body fat and the long-term risks of type 2 diabetes and the major cardiovascular diseases: coronary artery disease, stroke, heart failure and irregular heart rhythm (atrial fibrillation).
Mendelian randomization is a technique that uses genetic variants as surrogates for a particular risk factor (in this case, caffeine levels in the blood) to obtain genetic evidence that supports a particular outcome (in this study, weight (BMI) and the risk of type 2 diabetes).
The researchers analyzed the role of two common genetic variants of the CYP1A2 and AHR genes in nearly 10,000 people of predominantly European descent, participating in 6 long-term studies. The CYP1A2 and AHR genes are related to the speed of caffeine metabolism in the body.
People who carry genetic variants associated with slower caffeine metabolism drink, on average, less coffee and yet have higher levels of caffeine in their blood than people who metabolize it rapidly to reach or maintain the necessary levels for its stimulant effects.
The results of the analysis showed that higher genetically predicted levels of caffeine in the blood were associated with lower weight (BMI) and body fat.
Higher genetically predicted blood levels of caffeine were also associated with a lower risk of type 2 diabetes.
Next, the researchers used Mendelian randomization to further explore the extent to which any effect of caffeine on type 2 diabetes risk might be primarily due to concurrent weight loss.
The results showed that weight loss drove nearly half (43%) of the effect of caffeine on type 2 diabetes risk. No strong associations emerged between genetically predicted blood caffeine levels and the risk of any of the diseases cardiovascular studied.
The researchers acknowledge several limitations in their findings, such as the use of only two gene variants and the inclusion of only people of European descent.
But caffeine is known to stimulate metabolism, increase fat burning and reduce appetite, they explain. And it is estimated that a daily intake of 100 mg increases energy expenditure by about 100 calories per day, which could reduce the risk of developing obesity.
"Our Mendelian randomization finding suggests that caffeine could explain, at least in part, the inverse association between coffee consumption and type 2 diabetes risk," the researchers write. "Randomized controlled trials are warranted." to assess whether non-caloric caffeine-containing beverages could contribute to reducing the risk of obesity and type 2 diabetes," they conclude.