Karolinska Institutet researcher Susanna Larsson and colleagues investigated the potential causal effects of long term plasma caffeine concentrations on adiposity (body fat),type 2 diabetes, and major cardiovascular diseases.
Genetically predicted, lifelong, higher plasma caffeine concentrations were associated with lower body mass index and fat mass, as well as a lower risk of type 2 diabetes. Image credit: Sci.News.
Caffeine (1,3,7-trimethylxanthine) is a widely consumed psychoactive substance. The main sources of caffeine globally are coffee, tea, and soda drinks.
Considering the extensive intake of caffeine worldwide, even its small metabolic effects could have important health implications.
Caffeine has thermogenic effects and has been implicated in reducing weight, body mass index, and fat mass in short term randomized controlled trials.
Hence, a high caffeine intake might lower the risk of diseases related to adiposity, such as type 2 diabetes and cardiovascular disease.
“Previously published research indicates that drinking 3-5 daily cups of coffee, a rich source of caffeine, is associated with a lower risk of type 2 diabetes and cardiovascular disease. An average cup of coffee contains around 70-150 mg caffeine,” Dr. Larsson and co-authors said.
“But most of the published research to date has concerned observational studies, which can’t reliably establish causal effects, because of the other potentially influential factors involved.”
“What’s more, it’s difficult to disentangle any specific effects of caffeine from the other compounds included in caffeinated drinks and foods.”
To try and overcome these issues, the study authors used Mendelian randomization to find out what effect higher blood caffeine levels have on body fat and the long term risks of type 2 diabetes and major cardiovascular diseases: coronary artery disease, stroke, heart failure, and irregular heart rhythm (atrial fibrillation).
They looked at the role of two common genetic variants of the CYP1A2 and AHR genes in nearly 10,000 people of predominantly European ancestry, who were taking part in 6 long term studies.
The CYP1A2 and AHR genes are associated with the speed of caffeine metabolism in the body.
People who carry genetic variants associated with slower caffeine metabolism drink, on average, less coffee, yet have higher levels of caffeine in their blood than people who metabolize it quickly to reach or retain the levels required for its stimulant effects.
The results of the analysis showed that higher genetically predicted blood caffeine levels were associated with lower weight and body fat.
Higher genetically predicted blood caffeine levels were also associated with a lower risk of type 2 diabetes.
The researchers then used Mendelian randomization to further explore the extent to which any effect of caffeine on type 2 diabetes risk might principally be driven by the 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 studied cardiovascular disease outcomes.
“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,” the researchers said.
“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 study was published in the journal BMJ Medicine.
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S.C. Larsson et al. 2023. Appraisal of the causal effect of plasma caffeine on adiposity, type 2 diabetes, and cardiovascular disease: two sample mendelian randomisation study. BMJ Medicine 2; doi: 10.1136/bmjmed-2022-000335
Source : Breaking Science News