An analysis showed that genetically predicted higher levels of caffeine in the blood were associated with lower body weight (BMI) and body fat. Additionally, genetically predicted higher blood caffeine levels were also associated with a lower risk of type 2 diabetes.
Exploring the potential role of calorie-free caffeinated beverages may now be warranted, say the researchers.
High levels of caffeine in the blood could reduce the amount of body fat a person carries and their risk of type 2 diabetes, suggests research published March 14 in the open-access journal BMJ Medicine.
In light of their findings, the potential role of calorie-free caffeinated beverages in reducing the risk of obesity and type 2 diabetes is probably worth exploring, the researchers say.
Previously published research indicates that drinking 3 to 5 cups of coffee per day, a rich source of caffeine, is associated with a lower risk of type 2 diabetes and cardiovascular disease, the researchers note. An average cup of coffee contains about 70-150 mg of caffeine.
But most of the research published to date has been observational studies, which cannot reliably establish causal effects, due to the other potentially influential factors involved, the researchers point out.
Moreover, it is difficult to disentangle the specific effects of caffeine from other compounds included in caffeinated drinks and foods, they add.
The most popular sources of caffeine in the diet are coffee and tea. According to a survey by the National Coffee Association, 64% of Americans aged 18 or older drink coffee daily, while a survey by the Tea Association of the USA found that 84% of Americans drink tea. Other sources of caffeine such as soft drinks, energy drinks and chocolate products are also popular, but coffee and tea remain the most widely consumed sources of caffeine.
In an attempt to overcome these issues, researchers used Mendelian randomization to determine the effect of high levels of caffeine in the blood on body fat and the long-term risks of type 2 diabetes and major cardiovascular disease – coronary heart disease. , stroke, heart failure and irregular heartbeat (atrial fibrillation).
Mendelian randomization is a technique that uses genetic variants as a proxy for a particular risk factor – in this case, blood caffeine levels – to obtain genetic evidence to support a particular outcome – in this study, the weight (BMI) and the risk of type 2 diabetes.
The researchers looked at the role of two common genetic variants in the CYP1A2 and AHR genes in nearly 10,000 people of mostly European ancestry, who participated in 6 long-term studies. The CYP1A2 and AHR genes are associated with the rate of caffeine metabolism in the body.
People with genetic variants associated with slower caffeine metabolism drink less coffee on average, but have higher levels of caffeine in their blood than people who metabolize it rapidly to reach or maintain the levels required for its effects. stimulants.
The results of the analysis showed that genetically predicted higher blood caffeine levels were associated with lower weight (BMI) and lower body fat.
Genetically predicted higher 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 be primarily driven by concurrent weight loss.
The results showed that weight loss was responsible for almost half (43%) of the effect of caffeine on the risk of type 2 diabetes.
No strong association emerged between genetically predicted blood caffeine levels and risk of any of the cardiovascular disease outcomes studied.
The researchers acknowledge various limitations to their findings, including the use of only two genetic variants and the inclusion of only people of European ancestry.
But caffeine is known to boost metabolism, increase fat burning and reduce appetite, they explain. And it is estimated that a daily intake of 100 mg increases energy expenditure by about 100 calories per day, which could therefore reduce the risk of developing obesity.
“Our Mendelian randomization finding suggests that caffeine may, at least in part, explain the inverse association between coffee consumption and risk of type 2 diabetes,” the researchers write.
“Randomized controlled trials are warranted to assess whether noncaloric caffeinated beverages might play a role in reducing the risk of obesity and type 2 diabetes,” they conclude.
Reference: “Assessment of the causal effect of[{” attribute=””>plasma caffeine on adiposity, type 2 diabetes, and cardiovascular disease: two sample mendelian randomisation study” by Susanna C Larsson, Benjamin Woolf and Dipender Gill, 14 March 2023, BMJ Medicine.
DOI: 10.1136/bmjmed-2022-000335
Funding: Swedish Research Council for Health, Working Life and Welfare; Swedish Heart Lung Foundation; Swedish Research Council