Caffeine is a widely consumed psychoactive substance. The main sources of caffeine globally are coffee, tea, and soda drinks. Due to its thermogenic effects, caffeine has been implicated in reducing weight, body mass index (BMI), and fat mass in short-term randomized controlled trials. Other evidence also supports the inverse association between coffee consumption and reduced risk of type 2 diabetes.
A new study- from Imperial College London in collaboration with the University of Bristol, the London School of Hygiene and Tropical Medicine, and Uppsala University in Sweden- investigated the potential causal effects of long-term plasma caffeine concentrations on adiposity, type 2 diabetes, and major cardiovascular diseases.
It found that high blood caffeine levels may reduce the body weight a person carries and their risk of type 2 diabetes.
Scientists looked at the effect of higher blood caffeine levels on body weight and the long-term risks of type 2 diabetes and major cardiovascular diseases, such as coronary artery disease, stroke, heart failure, and irregular heart rhythm (atrial fibrillation).
The causal association between a trait and an outcome was examined using the statistical method known as Mendelian randomization, which makes use of genetic variants as a tool.
Their data revealed that decreased body weight (BMI) was associated with greater genetically predicted blood caffeine levels. Reduced risk of type 2 diabetes was also connected with higher genetically indicated blood caffeine levels.
According to research, it may be worth exploring the potential for calorie-free caffeinated drinks to play a role in lowering the risk of obesity and type 2 diabetes.
Scientists, using Mendelian randomization, studied 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 six long-term studies. The CYP1A2 and AHR genes are associated with the speed of caffeine metabolism in the body.
Compared to persons who quickly metabolize caffeine to achieve or maintain the levels necessary for its stimulant effects, people who carry genetic variations associated with slower caffeine metabolism tend to drink less coffee overall but have greater blood levels of the stimulant.
The impact of concomitant weight loss on any impact of caffeine on type 2 diabetes risk was also examined by the scientists. Results showed that 43% of the effect of caffeine on type 2 diabetes risk was driven by weight loss.
No strong associations emerged between genetically predicted blood caffeine levels and the risk of any of the studied cardiovascular disease outcomes.
Dr Dipender Gill, senior author for the study, from Imperial College London’s School of Public Health, said: “These findings offer important insight into the potential causal effect of caffeine on adiposity [obesity] and diabetes risk. However, further clinical study is warranted before individuals should use these results to guide their dietary preferences.”
Journal Reference:
- Susanna C Larsson, Benjamin Woolf and Dipender Gill. Appraisal of the causal effect of plasma caffeine on adiposity, type 2 diabetes, and cardiovascular disease: two sample mendelian randomization study. BMJ Medicine 2023;2: DOI: 10.1136/bmjmed-2022-000335