A new study reveals that 12 weeks of supplementation with the coffee compound cafestol significantly reduces body weight and visceral fat in people at risk for type 2 diabetes.
Study: Effects of 12-week supplementation with the coffee diterpene cafestol in healthy subjects with increased waist circumference: A randomized, placebo-controlled trial. Image Credit: PeopleImages.com – Yuri A/Shutterstock.com
Researchers conducted a randomized controlled trial (RCT) in a recent Nutrients study to evaluate the effects of pure cafestol on insulin sensitivity and glucose tolerance in healthy subjects with increased waist circumference at risk of developing insulin-dependent diabetes.
Background
Diabetes is a growing metabolic disorder that affects millions of people worldwide. It is important to discover safe and cost-effective approaches to the prevention and management of diabetes. Studies demonstrate an inverse relationship between coffee consumption and insulin-dependent diabetes, although causal evidence is lacking.
Most coffee intervention studies use instant coffee, which has a low amount of diterpenes such as caveol and cafestol. Cafestol, a bioactive molecule found in coffee, has been shown to lower blood glucose levels and increase insulin secretion.
However, its long-term effects on fat mass, glucose metabolism, and potential as a type 2 or insulin-independent diabetes prevention strategy remain unknown.
About the study
In the present double-blind RCT, researchers investigated whether administration of cafestol to healthy subjects with a large waist circumference could enhance responses to mixed meals, insulin sensitivity, and body fat ratios.
Researchers conducted the trial at the Steno Center in Aarhus, Denmark, including 40 adults aged up to 80 years with a waist circumference greater than 102 cm for men and 88 cm for women.
None were pregnant or lactating, had type 2 diabetes or other significant comorbidities, glycated hemoglobin (HbA1c) greater than 6.5%, or were taking antidiabetic medications.
Participants were randomized 1:1 to receive 6.0 mg cafestol capsules (intervention) or a placebo twice daily for 12 weeks. They visited the center six times for the study. At the initial visit, researchers inserted continuous glucose monitoring (CGM) sensors into one of the participants’ arms to measure glucose levels.
They placed ambulatory blood pressure monitors (ABPM) in the alternate arm to record blood pressure for 24 hours. At the next visit, subjects underwent a mixed meal test (MMT) and magnetic resonance imaging (MRI) and provided blood samples.
At the third study visit, subjects completed an insulin suppression test (IST), after which the researchers began the intervention. Six weeks after the intervention, they assessed kidney and liver function using blood samples from the participants.
The fourth (10 to 11 weeks after the third visit), fifth, and sixth visits were similar to the first, second, and third visits, respectively. Participants completed questionnaires to indicate adherence to the intervention at six weeks.
Primary outcomes included steady-state plasma glucose (SSPG) levels during IST and four-hour total area under the curve (tAUC) values for glucose during MMT. Secondary outcomes included tAUC values for triglycerides (TG), glucagon and insulin during magnetic resonance spectroscopy, HbA1c and MMT.
Other outcomes included subcutaneous and visceral fat volumes measured by MRI, blood pressure while awake and asleep, mean blood glucose, glucose variability, and time within normal range measured by CGM.
Study recruitment began on April 23, 2022. Intervention began on June 22, 2022, and the final participant visit occurred on December 22, 2022.
Participants were allowed to drink unlimited amounts of low diterpene drip and instant coffee but only one cup of unfiltered coffee beverage (French-style coffee, expresso coffee, or brewed coffee) per day.
Results
The ages of the participants ranged between 25 and 78 years. Among participants, 6.0 mg cafestol consumed twice daily did not improve glucose tolerance or insulin sensitivity, but significantly reduced body weight, visceral fat volumes, and γ-glutamyl transferase levels by 2.0% , 5.0% and 15%, respectively. compared to placebo.
Mean visceral fat volumes were significantly reduced by 400 mL among cafestol recipients. Additionally, the team observed a statistically significant difference between groups in weight/body mass index change.
Cafestol users lost 880 g of weight, while placebo users gained 920 g. In addition, the intervention group showed significantly higher free fatty acid (FFA) levels in the initial (hypoinsulinemic) than in the subsequent (hyperinsulinemic) stage of IST compared to the placebo group. Baseline FFA levels could indicate increased insulin resistance in the adipose tissues of cafestol consumers.
No participant showed abnormal changes in liver or kidney function. Cafestol moderately increased alanine aminotransferase levels in a subject with infectious mononucleosis. Side effects included increased flatulence, nausea, loose stools and mild headaches.
Six mg of cafestol did not alter low-density lipoprotein (LDL), total cholesterol, or blood pressure. The findings suggest that the dosage used in the present study is unlikely to have a cardiovascular risk.
Conclusion
The study found that cafestol could reduce body weight, visceral fat and γ-glutamyl transferase levels. Cafestol did not affect glucose tolerance or insulin sensitivity, but may contribute to the observed inverse association between coffee consumption and non-insulin-dependent diabetes.
Future studies need to determine the effects of higher doses given for prolonged periods, especially among people with impaired glucose metabolism and non-insulin-dependent diabetes.
