Caffeine intake causally associated with lower BMI, type 2 diabetes risk

 My 12 cup pot of coffee a day habit hasn't yet translated into a lower BMI.

Caffeine intake causally associated with lower BMI, type 2 diabetes risk

Key takeaways:

• A study found evidence that supports causal associations of higher plasma caffeine concentrations with lower weight and type 2 diabetes risk.
• The reduction in BMI was attributed to nearly half of caffeine’s effect on the risk for type 2 diabetes.

A high caffeine level in plasma was associated with reduced body fat and a lower risk for type 2 diabetes, according to a two-sample Mendelian randomization study published in BMJ Medicine.

Susanna C. Larsson, an associate professor of epidemiology and principal researcher with the Karolinska Institutet in Sweden, and colleagues wrote that previous observational studies have demonstrated that caffeine intake reduces weight and fat mass, and that drinking coffee specifically is linked to a lower risk for CVD and type 2 diabetes. However, “observational studies cannot reliably infer causality” since there could be confounded associations, they wrote.

Data derived from: Larsson SC, et al. BMJ Med. 2023;doi:10.1136/bmjmed-2022-000335.

“Furthermore, the specific effect of caffeine on the risk of cardiometabolic diseases might be difficult to disentangle from the other compounds included in caffeinated drinks and foods,” Larsson and colleagues wrote.

So, the researchers conducted a two-sample Mendelian randomization study, which simulates randomized trial groups using genetic variants in place of risk factors, to evaluate the possible causal impacts that long-term plasma caffeine concentrations might have on adiposity, CVD and type 2 diabetes. They looked at the role of two common genetic variants of the CYP1A2 and AHR genes, which are linked to how quickly the body metabolizes caffeine.

“Individuals who carry genetic variants that are associated with slower caffeine metabolism consume, on average, less coffee but have higher plasma caffeine concentrations,” the researchers wrote. “This finding probably relates to individuals with a slow metabolism of caffeine consequently consuming less coffee and caffeine than people who have a fast caffeine metabolism, to reach or retain the concentrations of caffeine required for the desired psychostimulant effects.”

The researchers studied outcomes like atrial fibrillation, BMI, heart failure, ischemic heart disease, type 2 diabetes, stroke, whole body fat mass and whole body fat-free mass among participants who were primarily of European descent.

Larsson and colleagues found that higher genetically predicted plasma caffeine concentrations were linked to lower BMI (beta = -0.08 SD; 95% CI, -0.1 to -0.06), whole body fat mass (beta = -0.06 SD; 95% CI, 0.08 to 0.04) and a lower risk for type 2 diabetes (OR = 0.81; 95% CI, 0.74-0.89).

The researchers additionally noted that the reductions in BMI drove nearly half (43%; 95% CI, 30-61) of the impact that caffeine had on the risk for type 2 diabetes.

“The association of caffeinated or total coffee consumption with the risk of type 2 diabetes has been examined in many observational studies, which collectively support an inverse dose-response relation,” the researchers wrote. “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.”

However, there were no strong associations between genetically predicted plasma caffeine concentrations and risk for CVD.

Larsson and colleagues concluded that higher plasma caffeine concentrations may causally reduce adiposity and the risk for type 2 diabetes, but further research to assess the translational potential of these findings towards reducing the burden of metabolic disease is needed.

“This Mendelian randomization study found evidence to support causal associations of higher plasma caffeine concentrations with lower adiposity and risk of type 2 diabetes,” the researchers wrote. “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.”