the results of a new study suggest.
Explaining that caffeine has thermogenic effects, the researchers note that previous short-term studies have linked caffeine intake with reductions in weight and fat mass. And observational data have shown associations between coffee consumption and lower risks of type 2 diabetes and cardiovascular disease.
In an effort to isolate the effects of caffeine from those of other food and drink components, Susanna C. Larsson, PhD, of the Karolinska Institute, Stockholm, and colleagues used data from studies of mainly European populations to examine two specific genetic mutations that have been linked to a slower speed of caffeine metabolism.
The two gene variants resulted in “genetically predicted, lifelong, higher plasma caffeine concentrations,” the researchers note “and were associated with lower body mass index and fat mass, as well as a lower risk of type 2 diabetes.”
Approximately half of the effect of caffeine on type 2 diabetes was estimated to be mediated through body mass index (BMI) reduction.
The work was published online March 14 in BMJ Medicine.
“This publication supports existing studies suggesting a link between caffeine consumption and increased fat burn,” notes Stephen Lawrence, MBChB, Warwick (England) University. “The big leap of faith that the authors have made is to assume that the weight loss brought about by increased caffeine consumption is sufficient to reduce the risk of developing type 2 diabetes,” he told the UK Science Media Centre.
“It does not, however, prove cause and effect.”
The researchers agree, noting: “Further clinical study is warranted to investigate the translational potential of these findings towards reducing the burden of metabolic disease.”
Katarina Kos, MD, PhD, a senior lecturer in diabetes and obesity at the University of Exeter (England), emphasized that this genetic study “shows links and potential health benefits for people with certain genes attributed to a faster [caffeine] metabolism as a hereditary trait and potentially a better metabolism.”
“It does not study or recommend drinking more coffee, which was not the purpose of this research,” she told the UK Science Media Centre.
Using Mendelian randomization, Dr. Larsson and colleagues examined data that came from a genomewide association meta-analysis of 9,876 individuals of European ancestry from six population-based studies.
Genetically predicted higher plasma caffeine concentrations in those carrying the two gene variants were associated with a lower BMI, with one standard deviation increase in predicted plasma caffeine equaling about 4.8 kg/m2 in BMI (P < .001).
For whole-body fat mass, one standard deviation increase in plasma caffeine equaled a reduction of about 9.5 kg (P < .001). However, there was no significant association with fat-free body mass (P = .17).
Genetically predicted higher plasma caffeine concentrations were also associated with a lower risk for type 2 diabetes in the FinnGen study (odds ratio, 0.77 per standard deviation increase; P < .001) and the DIAMANTE consortia (0.84, P < .001).
Combined, the odds ratio of type 2 diabetes per standard deviation of plasma caffeine increase was 0.81 (P < .001).
Dr. Larsson and colleagues calculated that approximately 43% of the protective effect of plasma caffeine on type 2 diabetes was mediated through BMI.
They did not find any strong associations between genetically predicted plasma caffeine concentrations and risk of any of the studied cardiovascular disease outcomes (ischemic heart disease, atrial fibrillation, heart failure, and stroke).
The thermogenic response to caffeine has been previously quantified as an approximate 100 kcal increase in energy expenditure per 100 mg daily caffeine intake, an amount that could result in reduced obesity risk. Another possible mechanism is enhanced satiety and suppressed energy intake with higher caffeine levels, the researchers say.
“Long-term clinical studies investigating the effect of caffeine intake on fat mass and type 2 diabetes risk are warranted,” they note. “Randomized controlled trials are warranted to assess whether noncaloric caffeine-containing beverages might play a role in reducing the risk of obesity and type 2 diabetes.”
The study was supported by the Swedish Research Council for Health, Working Life and Welfare, Swedish Heart Lung Foundation, and Swedish Research Council. Dr. Larsson, Dr. Lawrence, and Dr. Kos have reported no relevant financial relationships.
A version of this article first appeared on Medscape.com.