Human volunteers taking a daily supplement of the commercially available lychee extract Oligonol lost about three centimetres in their waist size, as well as a 6 per cent reduction in subcutaneous fat area and a 15 per cent reduction in abdominal (visceral) fat.
“In this study, we demonstrated the effect of Oligonol on metabolic syndrome using clinical parameters characterized by abdominal visceral fat area and insulin resistance,” wrote the researchers. “We revealed that Oligonol reduced BMI and subcutaneous and visceral fat volumes, and improved insulin resistance,” report researchers from Hokkaido Information University, Sapporo Bio-S, and Amino Up Chemical Company in Japan in the Journal of Functional Foods.
“In particular, remarkable reduction of visceral fat areas was observed,” they noted.
“These findings strongly indicate that Oligonol would be a beneficial supplement for prevention and improvement of metabolic syndrome, especially in the stage of hyperinsulinemia often seen during pre-diabetic conditions,” added the researchers.
Metabolic syndrome (MetS) is a condition characterised by central obesity, hypertension, and disturbed glucose and insulin metabolism. The syndrome has been linked to increased risks of both type-2 diabetes and cardiovascular disease (CVD).
The Japanese researchers recruited 18 adult volunteers with waist circumference over 85 cm. Subjects were aged between 24 and 59. Volunteers were randomly divided into two groups – one received a daily Oligonol dose of 50 milligrams, while the other received placebo.
After 10 weeks of study, in addition to the improvements in waist circumference, an abdominal fat, improvements in insulin resistance were recorded in the Oligonol group, compared to placebo, and these occurred with increases in blood levels of adiponectin, a hormone that regulates a number of metabolic processes.
“It is evident that the enhanced presence of oligomerized proanthocyanidins in Oligonol may offer a wide-range of benefits in pharmaceutical preparations, food products, and dietary supplements as well as in the development of functional beverages,” concluded the researchers.
The ingredient is available from the Maypro Group in the US, and New Dietary Ingredient (NDI) status for the proprietary lychee extract was secured in 2007.
Maypro claims the ingredient is unique because it makes use of a patented technology that boosts polyphenol bioavailability and in turn enhances anti-oxidant performance.
According to Maypro, the high molecular weight of many polyphenols hinders their absorption by the body. However, the company's affiliate supplier in Japan, Amino Up Chemical, has developed a production process that involves oligomerization, which shortens polyphenol polymers into monomers and oligomers for increased bioavailability.
Source: Journal of Functional Foods
Published online ahead of print, doi: 10.1016/j.jff.2009.09.002
“Amelioration of abdominal obesity by low-molecular-weight polyphenol (Oligonol) from lychee”
Authors: J. Nishihira, M. Sato-Ueshima, K. Kitadate, K. Wakame, H. Fujii