Caffeine is consumed worldwide in coffee, tea, and soft drinks, and its health benefits have been studied for years. We determined how levels of caffeine in the blood affect body fat and the risk of type 2 diabetes and cardiovascular disease.
A standard cup of coffee (8 ounces or about 250 ml in the US) contains 70-150 mg of caffeine. By comparison, a 12 ounce (about 350 ml) caffeinated soft drink typically contains 30 to 40 mg of caffeine, and an 8 ounce cup of green or black tea contains 30 to 50 mg. .
Small, short-term studies have shown that caffeine consumption reduces body mass index (BMI) and body fat mass, but the long-term effects are unknown. Other studies have observed that drinking 3 to 5 cups of coffee daily reduces the risk of type 2 diabetes and cardiovascular disease. However, most studies have not been able to reliably establish a causal relationship between caffeine intake and disease.
Caffeine is metabolized primarily in the liver, and its metabolism can be affected by mutations in the genes CYP1A2 and AHR. People with mutations in these genes metabolize caffeine more slowly, so on average they consume less coffee but have higher blood caffeine levels.
A new study examines these genetic variants using a Mendelian randomization framework to determine whether long-term exposure to higher blood caffeine levels is causally associated with BMI, type 2 diabetes, and cardiovascular disease. was investigated.
Using the Mendelian randomization method, genetic variants that are positively associated with a modifiable risk factor (here, blood caffeine levels) are used to provide evidence for the causal relationship of that risk factor. can do. Effects of other substances in caffeinated beverages.
Researchers analyzed data from a genome-wide association study (GWAS) of 9,876 individuals of European descent to examine the role of genetic mutations in CYP1A2 and AHR.
The analysis showed that higher genetically predicted blood caffeine levels were associated with lower BMI and body fat, and a lower risk of type 2 diabetes. Furthermore, nearly half (43%) of the impact on diabetes risk was due to decreased BMI. There was no evidence of a significant association between genetically predicted elevated blood caffeine levels and cardiovascular disease, particularly ischemic heart disease, atrial fibrillation, heart failure, and stroke.
The researchers point to the use of Mendelian randomization techniques as a strength of their study, as the use of fixed genetic variants reduces bias.
“Our Mendelian randomization findings suggest that caffeine may at least partially explain the inverse association between coffee consumption and type 2 diabetes risk.
They recognized the limitations of the study, one of which was that the participants were of European descent only, so the results may not be generalizable to non-European populations. Based on the results of this study, we believe that it is necessary to consider incorporating caffeinated beverages as a preventive measure.
“Randomized controlled trials are needed to assess whether zero-calorie caffeinated beverages play a role in reducing the risk of obesity and type 2 diabetes,” the researchers said.
The study was published in a journal BMJmedicine.
Source: Karolinska Institutet via Simex
