From Ergo Log
Endurance athletes who take 200 mg lychee extract daily for a month can keep going for longer at a high level of intensity. Korean researchers at Seoul National University describe the performance enhancing effect of lychee extract in the Journal of Clinical Biochemistry and Nutrition.
Lychees contain polyphenols such as cyanidin-3-rutinoside [structural formula shown below], cyanidin-glucoside, quercetin-3-rutinoside (better known as rutin) and quercetin-glucoside. [J Agric Food Chem. 2000 Dec;48(12):5995-6002.] Asian researchers have published regularly on the positive health effects of phenol-rich lychee extracts over the past six years.
According to these publications, lychee extracts inhibit inflammation processes in athletes [Phytother Res. 2011 Oct;25(10):1486-93.], they protect the brain against the effects of aging [Br J Nutr. 2013 Nov 14;110(9):1549-58.], they reduce the chance of influenza viruses entering cells [Phytomedicine. 2010 Nov;17(13):1047-56.], and they kill gut cancer cells [J Biomed Biotechnol. 2012;2012:341479.] and breast cancer cells [Toxicol Appl Pharmacol. 2006 Sep 1;215(2):168-78.].
The Koreans were curious to know whether the phenols in lychee could also help improve endurance sports performance, so they did a 30-day experiment with about sixty adult males. They were physically active but did not do any sports.
The researchers divided the men into three groups. One control group were given a placebo, the second control group took 800 mg vitamin C and 320 IE vitamin E daily. The experimental group took 200 mg daily of a lychee extract called Oligonol.
Oligonol is manufactured by the Japanese Amino-Up Chemical. It contains an alcohol-based extract of lychee and an extract of green tea. Previous tests on athletes have shown that it reduces fatigue. [Adv Exerc Sports Physiol 2008; 13: 93–99.]
Before and after supplementation the researchers got the subjects to run on a treadmill at 80 percent of their VO2max. The figure below shows how many minutes the subjects managed to keep this up.
The men who had been given lychee extract were able to run for 3.87 minutes longer after the supplementation period than before. The increase represented a statistically significant effect.
The lychee extract had no effect on fat or muscle mass, nor did it have an antioxidant effect. It had no effect on the subjects’ maximal oxygen intake either.
The extract did have an effect on the men’s anaerobic threshold. This is the level of exertion at which your muscles are no longer capable of burning glucose efficiently and your lactate level start to rise. In trained endurance athletes this occurs at an intensity of 85-90 percent of maximal oxygen uptake; in untrained people this can occur at 55 percent of their maximal oxygen uptake.
Before supplementation started the subjects anaerobic threshold was at 59.1 percent of their VO2max; after 30 days of supplementation this had risen to 65.1 percent.
“Further studies are recommended to confirm the clinical efficacy of oligomerized lychee fruit extract on endurance exercise […]”, the Koreans conclude. “It would also be useful and interesting to conduct a similar study that involves individuals engaged in an endurance training program or trained endurance athletes.”
The study was funded by Amino-Up Chemical, the manufacturer of the lychee extract that was tested.
J Clin Biochem Nutr. 2012 Mar;50(2):106-13.