Looking for a supplement or food that will enhance your memory? Why not try the longan [Euphoria longana], an Asian fruit that resembles the lychee? According to pharmacologists at Kyung Hee University in South Korea, water-based extracts of this fruit are as effective as the smartdrug piracetam.
Euphoria longana is not well known in the west, but is a regular part of the diet in Asian countries. Chinese healers use the dried fruit to treat insomnia and to help a failing memory. The Koreans did an animal study to find out whether Euphoria longana can indeed help to improve memory.
The researchers gave mice a daily oral dose of 50, 100, 200 or 400 mg Euphoria longana extract per kg bodyweight for a period of two weeks. The Koreans made the extracts themselves. They cooked dried longans for two hours in water, freeze-dried the filtrate and used the resulting powder for their experiment. Mice in control groups were given salt water or 400 mg piracetam per kg bodyweight.
To test the mice's memory, after 14 days of supplementation, the researchers placed the animals in a lit cage with a darkened area. Mice don't like strong light, so they tend to go in search of a darker place. But in this experiment, when they found the darker area they were given an electric shock. A day later the researchers repeated the experiment, and measured the amount of time that elapsed before the mice went in search of the darkened area again. The longer the amount of time, the better the mice had learned from their previous experiences.
The more Euphoria longana the mice had had, the longer it took for them to start looking for the dark area. In higher doses, the extract worked as effectively as the smart drug piracetam.
The 200 mg dose of Euphoria longana [ELE] boosted the production of the growth factor BDNF in the mice's brains. BDNF prompts brain cells to make new connections. The production of BDNF is controlled by the transcription factor CREB. And indeed: the researchers found more active pCREB in the CA1 and DG regions of the hypothalamus of the mice.
"Here, we demonstrate that Euphoria longana extract enhances memory performance in vivo", the researchers conclude. "More importantly, the present results suggest that enhanced BDNF upregulation and neurogenesis contribute to memory performances."
J Ethnopharmacol. 2010 Mar 2;128(1):160-5.