Belonging to the soapberry family, Lychee is a fruit naturally found in tropical areas of the Philippines, Indonesia, Vietnam, Taiwan and China.  It is also cultivated in India during summer months primarily for its health benefits.  A rough, reddish-pink rind covers white layers of sweet fruit similar in taste to grapes.  In the center is a non-edible brown seed.  

In addition to a tangy, sweet flavor, lychee is packed with many beneficial nutrients.  It is a rich source of vitamin C, containing almost 40% more than an orange.  Lychee is also high in beta-carotene and important unsaturated fatty acids that help with the absorption of beta-carotene and other fat-soluble vitamins.  It is also a good source of fiber, which makes it valuable for the digestive system.  Advocates of lychee also claim that the juicy fruit enhances energy, boosts well-being and acts as a diuretic.

Oligonol® is an extract of lychee fruit that is commercially manufactured. Clinical studies with Oligonol have shown potential benefits for the skin, specifically the subdermal layer, from damage caused by ultra violet light and free radicals and possible enhancement of cardiovascular function.  Oligonol is marketed in Japan as an ingredient in supplements, cosmetics and food, and it has been accepted as a "New Dietary Ingredient" by the U. S. Food and Drug Administration.  

One promising study examined the use of Oligonol on subjects with metabolic syndrome (MetS), characterized by hypertension, obesity and inhibited insulin resistance.  MetS has been linked to Type 2 diabetes and cardiovascular disease.  The study looked at 18 adult subjects (14 males and 4 females) between 24 and 59 years of age with an abdominal circumference over 85 cm.  Subjects were randomly divided into two groups taking either two 50 mg capsules of Oligonol or a placebo twice a day for 10 weeks.

Following this period, measurements were taken for body weight, abdominal circumference and volume of visceral fat.  Oligonol subjects experienced a significant reduction in body weight, abdominal circumference and visceral fat and an improvement in insulin resistance as compared to the control group.  The researchers concluded that   …”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.”

Another recent study published in Nutrition Research and Practice examined anti-inflammatory effects in humans consuming Oligonol.  Cortisol and cytokines are inflammatory markers that are increased with stress attributed to exercise.  This study looked at the effects of Oligonol consumption on cortisol and related cytokines in nineteen healthy, sedentary males, both at rest and following physical exercise.

Each man consumed 100 mg of Oligonol twice a day with water or a placebo for four weeks.  Measurements in body composition, white blood cells and serum levels of cortisol and inflammatory cytokines (interleukin (IL)-1beta and IL-6) were taken before and after the four-week period.  Results showed that consumption of Oligonol significantly reduced serum levels of cortisol and inflammatory cytokines both at rest and following physical exercise.

Health properties of lychee offer an exciting area for nutritional research.  The few studies that have been done will hopefully lead to other important research in the areas of general health and human performance.

Sources:
Nishihira, J., Sato-Ueshima, M., Kitadate, K., Wakame, K., Fujii. H. Amelioration of abdominal obesity by low-molecular-weight polyphenol (Oligonol) from lychee.  Journal of Functional Foods, 2009; 10.1016

Jeong-Beom Lee, Young-Oh Shin, Young-Ki Min, and Hun-Mo Yang. The effect of Oligonol intake on cortisol and related cytokines in healthy young men.  Nutrition Research and Practice, 2010; 4(3):203-207 DOI: 10.4162/nrp.2010.4.3.203