Galacto-oligosaccharides ameliorate dysbiotic Bifidobacteriaceae decline in Japanese patients with type 2 diabetes

Gut microbiota affects the host’s metabolism, and it is suggested that there are differences in gut microbiota composition between patients with type 2 diabetes and healthy individuals. Additionally, dysbiosis may increase the concentration of lipopolysaccharides (LPS), causing metabolic endotoxemia, which induces impaired glucose tolerance. Several studies have reported relationships between metabolic diseases and the gut microbiota; and prebiotics, such as oligosaccharides, are commonly consumed to regulate gut microbiotas in healthy individuals. Galacto-oligosaccharides (GOS) are a major prebiotic, which specifically increase Bifidobacteriaceae abundance. Recent studies have reported that Bifidobacteriaceae improved metabolic endotoxemia or impaired glucose tolerance. However, there are few studies reporting the effects of GOS on patients with type 2 diabetes. In the current study, we compared clinical parameters, faecal gut microbiota, their associated metabolic products and their components such as LPS, and LPS-binding protein (LBP) produced by the host, between patients with diabetes and healthy controls. We then assessed the effects of GOS on glycaemic control, and gut microbiotas and metabolites in patients with type 2 diabetes in a double-blind controlled manner. LBP levels were significantly higher in patients with diabetes than those of healthy subjects, which was consistent with previous reports. The abundance of Bifidobacteriaceae and the diversity of intestinal microbiota were significantly lower in patients with diabetes than in healthy subjects. Interestingly, Bifidobacteriaceae was markedly restored in patients with diabetes after consumption of GOS, whereas LBP and glucose tolerance did not improve during this short-term trial period. In the present study, we demonstrated that GOS can ameliorate dysbiosis in patients with diabetes, and continuous intake of GOS may be a promising method for managing type 2 diabetes.

Cross-cultural epidemiology

Two issues led me into the area of cross-cultural psychiatric epidemiology in the 1980s. The National Institute of Mental Health funded the Epidemiological Catchment Area Studies. One of them included a study of a Caucasian and Hispanic populations in Los Angeles. Dr Masaaki Kato, then the Director of the National Institute of Mental Health of Japan, was the consultant for a JAICA-funded project in Lima, Peru. He was interested in fostering psychiatric research there, so I suggested an epidemiological study. This study was done in two phases with Drs Shunichiro Hayashi, Kimpei Minobe and Alberto Perales. Because it is extraordinarily expensive to undertake epidemiological studies in the USA, I met with colleagues regarding psychiatric epidemiological studies in Asia, Dr Chung-kyoon Lee at the Seoul National University in Korea, Dr Eng-Kung Yeh of the National Taiwan University in Taipei,Taiwan, Dr Char-nie Chen of the Chinese University of Hong Kong, and Dr Masaaki Kato in Japan. Studies have been completed in Korea, Taiwan, Hong Kong, but not in Japan. In the meantime, very small pilot studies among Asian groups in Los Angeles were performed. The very recent results of the study of Chinese in Los Angeles, California, with the Composite International Diagnostic Interview are now available to compare the prevalence of selected psychiatric disorders among the Chinese in Los Angeles and the data from the National Co-Morbidity Study.

Lifetime and twelve-month prevalence rates of major depressive episodes and dysthymia among Chinese Americans in Los Angeles

OBJECTIVE

The authors' goal was to estimate the lifetime and 12-month rates of major depressive episodes and dysthymia for Chinese Americans who reside in Los Angeles. This effort, the Chinese American Psychiatric Epidemiological Study, is the first large-scale community psychiatric epidemiological study on an Asian American ethnic group that used DSM-III-R criteria for major depressive episodes and dysthymia.

METHOD

A multi-stage sampling design was used to select respondents for participation in the survey. The sample included 1,747 adults, 18-65 years of age, who resided in Los Angeles County and who spoke English, Mandarin, or Cantonese.

RESULTS

Approximately 6.9% of the respondents had experienced an episode of major depression and 5.2% had had dysthymia in their lifetime. The 12-month rates of depressive episode and dysthymia were 3.4% and 0.9%, respectively. The most consistent correlate of lifetime and 12-month depressive episode and dysthymia was social stress, measured by past traumatic events and recent negative life events.

CONCLUSIONS

The Chinese American Psychiatric Epidemiological Study provides a rare opportunity to investigate the heterogeneity within a single Asian American ethnic group, Chinese Americans, and to identify the subgroups among Chinese Americans who may be most at risk for mental health problems.