Scientists from Nagoya University report that coffee prevented the development of high-blood sugar in lab mice, as well as improving their sensitivity to insulin, thereby reducing the risk of diabetes.
“Our results indicated that caffeine is one of the most effective anti-diabetic compounds in coffee,” wrote the researchers in the Journal of Agricultural and Food Chemistry.
“We hope to identify the target tissues upon which coffee or caffeine acts directly, as well as effective anti-diabetic compounds other than caffeine. However, the present results suggest that coffee consumption may help to prevent type-2 diabetes and metabolic syndrome,” they added.
The results are consistent with a growing body of research, much of which was pulled together in a meta-analysis in the Archives of Internal Medicine (Dec 2009, Vol. 169, pp. 2053-2063) by scientists from the University of Sydney, Australia. Data from over 500,000 individuals with over 21,000 cases of type-2 diabetes from prospective studies showed that drinking three to four coffee and tea may reduce the risk of developing diabetes by 25 percent.
Benefits of the bean
Coffee, one of the world's largest traded commodities produced in more than 60 countries and generating more than $70bn in retail sales a year, continues to spawn research and interest with data linking it to improved liver health, in addition to the potential anti-diabetes benefits.
Diabetes affects an estimated 24 million Americans, equal to 8 percent of the population. The total costs are thought to be as much as $174 billion, with $116 billion being direct costs from medication, according to 2005-2007 American Diabetes Association figures.
A strain of lab mice that develops diabetes were divided into two groups: One received normal drinking water while the other received diluted coffee. After five weeks of feeding, the researchers noted that coffee-drinking animals did not develop high blood sugar levels (hyperglycemia), while levels of pro-inflammatory cytokines, including monocyte chemoattractant protein 1 (MCP-1) and interleukin-6 (IL-6) were reduced, compared to controls.
Similar effects were also observed when animals were fed drinking water with caffeine added, said the researchers.
Bioactives in the bean
Beyond caffeine, other groups of researchers have come up with other suggestions for the potential mechanism. Some have noted that the potential benefits may be related to the antioxidant content, which may counter the oxidative stress that promotes dysfunction of beta cells in the pancreas and boost insulin resistance.
Another potential mechanism involves the chlorogenic acid content of coffee and the compounds it forms on degradation, with previous studies linking these degradation products to reduced glucose absorption in the intestine.
There is also evidence suggesting that the magnesium content of coffee may also play a role in the potential reduction in the risk of type-2 diabetes.
Source: Journal of Agricultural and Food Chemistry
2010, Volume 58, Number 9, Pages 5597–5603, doi: 10.1021/jf904062c
"Coffee and Caffeine Ameliorate Hyperglycemia, Fatty Liver, and Inflammatory Adipocytokine Expression in Spontaneously Diabetic KK-Ay Mice"
Authors: R. Yamauchi, M. Kobayashi, Y. Matsuda, M. Ojika, S. Shigeoka, Y. Yamamoto, Y. Tou, T. Inoue, T. Katagiri, A. Murai, F. Horio