Several studies have indicated that drinking between three to five cups of coffee per day could reduce the risk of developing type 2 diabetes and cardiovascular disease. However, most of this research has involved observational studies that cannot reliably establish causal effects due to other potentially influential factors, as well as the difficulty to disentangle any specific effects of caffeine from the other components included in caffeinated drinks and foods.
Now, an international team of scientists led by the Karolinska Institute in Sweden has used Mendelian randomization – a technique employing genetic variants as proxies for a particular risk factor – to examine what effect higher blood caffeine levels have on body fat and the long-term risks of developing type 2 diabetes and various cardiovascular issues, including artery disease, atrial fibrillation (irregular heart rhythm), heart failure, and stroke.
The experts investigated the role of two common genetic variants of the CYP1A2 and AHR genes – which are associated with the speed of caffeine metabolism in the organism – in a cohort of 10,000 individuals of predominantly European ancestry who were involved in six long-term studies. They started with the assumption that people who carry genetic variants linked to slower caffeine metabolism usually drink less coffee but have higher levels of caffeine in their blood than those who metabolize it faster.
The analysis revealed that higher genetically predicted blood caffeine levels were associated with lower body weight and fat, as well as a decreased risk of developing type 2 diabetes. By employing once more Mendelian randomization to further explore the extent to which caffeine effects on type 2 diabetes risk are driven by the concurrent weight loss, the researchers discovered that weight loss drove almost half (43 percent) of the effect of caffeine on diabetes risk. However, no significant associations between genetically predicted blood caffeine levels and the risk of cardiovascular disease emerged.
While these findings are limited by the use of only two genetic variants and the inclusion of only participants of European ancestry, they nevertheless suggest that caffeine plays a significant role in boosting metabolism, increasing fat burning, reducing appetite, and increasing energy expenditure, which could consequently lower the risk of developing obesity and thus type 2 diabetes.
“Our Mendelian randomization finding suggests that caffeine might, at least in part, explain the inverse association between coffee consumption and risk of type 2 diabetes. Randomized controlled trials are warranted to assess whether non-caloric caffeine containing beverages might play a role in reducing the risk of obesity and type 2 diabetes,” the authors concluded.
The study is published in the journal BMJ Medicine.
By Andrei Ionescu, Earth.com Staff Writer
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