12 January - 20 June 2016

Chinese yam extract prevents obesity

26 February 2015

Could the simple Chinese/Korean yam, Dioscorea batatas (DB) seen traditionally in South-East Asia as a treatment for inflammatory disease have any scientific validity?  With the emergence of recent studies demonstrating anti-obesity effects from DB supplementation in obese mice with metabolic diseases, a team of Korean scientists now believe so.
The focus of this particular study was to determine whether DB extract could reduce visceral fat accumulation and obesity related biomarkers in rodents fed a high fat diet (HFD) and whether genes associated with adipogenesis and inflammation could be modulated by diets containing DB extract.

The present study consisted of 4 test groups of male mice (n=10) fed an experimental diet: Normal Diet (ND), HFD, HFD plus 100mg/kg DB extract and HFD plus 200mg/kg DB extract. These test groups underwent the experimental diet for 14 weeks, and tested for obesity related biomarkers at 12 weeks.
Results indicated that the HFD group had significantly accelerated weight gain and higher final body weight compared to the ND group. However, subjects fed the DB supplement had a significant decrease in body weight compared to the HFG, with no discernible difference between the DB dosage groups. Additionally the test groups with DB supplementation displayed significantly reduced visceral fat accumulation.

Examination of adipose gene expression showed that regulators of adipogenic factors were significantly reduced in DB extract fed mice.  Likewise the expression of proinflammatory cytokines in adipose tissue was decreased significantly.  These findings are of particular interest as proinflammatory cytokines in adipose tissue have been linked to cardiovascular disease in obese patients.  Leptin levels were also investigated as an indicator for obesity; levels were shown to be greatly increased in the HFD test group resulting in suppression of cytokine signalling. Supplementation with DB at the higher dose appeared to prevent this increase in leptin and signalling suppression. It was therefore hypothesised that DB could potentially be utilised to prevent visceral adipose hypertrophy.  These findings are of particular interest as in obese states adipoctes release cytokines which act to amplify the effects of proinflammatory state within adipose tissue.  

It is hypothesised that the anti-obesity effects of DB are due to these cytokines.  It is believed that the high dose DB extract would be successful in reducing the expression of adipogenic genes and proinflammatory cytokines preventing accumulation of visceral fat in subjects.  However at this stage it is important to note that further studies are required to validate this theory and its effectiveness in human subjects.

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