Individuals with high blood caffeine levels may carry less body fat and have a reduced risk of developing type 2 diabetes, according to a new study from the Karolinska Institutet.
The study suggests that the use of calorie-free caffeinated drinks may be worth exploring for reducing the risk of obesity and type 2 diabetes.
Mendelian Randomization
Previous research has shown that drinking 3-5 cups of coffee, which contains 70-150 mg of caffeine, is associated with a lower risk of type 2 diabetes and cardiovascular disease.
However, most of the research conducted so far has been observational and cannot establish causal effects due to other potential factors.
To address this issue, the researchers used a technique called Mendelian randomization to determine the effect of higher blood caffeine levels on body fat and the long-term risk of type 2 diabetes and major cardiovascular diseases, including coronary artery disease, stroke, heart failure, and irregular heart rhythm (atrial fibrillation).
Mendelian randomization uses genetic variants as proxies for a particular risk factor to obtain genetic evidence to support a particular outcome.
In this case, the researchers examined the role of two common genetic variants of the CYP1A2 and AHR genes in nearly 10,000 people of predominantly European ancestry who were participating in six long-term studies.
These genes are associated with the speed of caffeine metabolism in the body.
What the Study Found
The study showed that people with higher genetically predicted blood caffeine levels had lower weight (BMI) and body fat, as well as a lower risk of type 2 diabetes.
The researchers also found that weight loss accounted for almost half (43%) of the effect of caffeine on type 2 diabetes risk.
However, no significant associations were found between genetically predicted blood caffeine levels and the risk of any of the studied cardiovascular disease outcomes.
The researchers acknowledged several limitations to their findings, including the use of only two genetic variants and the inclusion of only people of European ancestry.
However, caffeine is known to boost metabolism, increase fat burning, and decrease appetite. Studies have estimated that a daily intake of 100 mg of caffeine can increase energy expenditure by around 100 calories a day, which may lower the risk of obesity.
"Our mendelian randomisation finding suggests that caffeine might, at least in part, explain the inverse association between coffee consumption and risk of type 2 diabetes," the research team wrote.
"Randomised 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," they conclude.
The team's findings were published in the journal BMJ Medicine.
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