In a quest for naturally-occurring antioxidants for preventive health measures, we have focused on the Schisandra Berry, which is a commonly used herb in Chinese Medicine. Sun Simiao, who was renowned as the "King of Herbal Medicine" in the Tang Dynasty in China, anecdoted that "Taking Schisandra Berry can invigorate the Qi of the five visceral organs". This statement reveals much of the Qi-invigorating action of the Schisandra Berry in various organs of the body. The Schisandra Berry is called "Wǔ Wèi Zi" in Chinese, which literally means "the fruit of five tastes". According to the Five Element theory of Chinese Medicine, the five tastes of the Schisandra Berry indicate its pharmacological action targeting at five visceral organs; sour to liver, bitter to heart, sweet to spleen, pungent to lung and salty to kidney. To investigate the pharmacological basis of the Qi-invigorating action of the Schisandra Berry in various organs, we first isolate Schisandrin B, an active component of this Schisandra Berry. We then examine the effect of Schisandrin B on ROS-induced tissue damage in rats. Over the past two decades, experimental results have shown that Schisandrin B is protective against oxidant injury in various tissues including brain, heart, kidney, liver and skin. The tissue protection afforded by Schisandrin B in experimental animal has been validated by studies using cultured cells derived from various tissues. Pre-incubation of Schisandrin B was found to protect against oxidant injury induced in cultured cells. Further, in-depth investigations have revealed that the biochemical mechanism underlying the tissue or cellular protection afforded by Schisandrin B involves an increase in the resistance of mitochondria to ROS-induced oxidative stress. The oxidative stress induced disruption of mitochondrial structural and functional integrity can eventually lead to cell apoptosis, with the resultant development of age-associated diseases. The increase in mitochondrial resistant to oxidative stress results in enhanced cell survival and ultimately to a longer health lifespan. With regard to aging, "Mitochondrial Decay" is the leading hypothesis in explaining the cause of aging. Under normal conditions, mitochondrial generates more amount of ROS, which are beneficial in safeguarding health. When mitochondria was damaged by ROS, the resulting malfunction generally increase amounts of ROS, with further disruption of mitochondrial structural and functional integrity. In this regard, a growing body of scientific evidence has suggested that involvement of mitochondrial dysfunction in number of age-associated diseases such as Alzheimer's disease, Parkinson's disease, cardiovascular diseases, diabetic complications and liver diseases. The "Mitochondrial Decay" theory of aging is supported by the demonstration of a negative correlation between the extent of mitochondrial ROS production in tissues such as that of the liver and maximum lifespan of a number of primates, including humans. The extrapolation from the correlation graph indicates that humans should be able to live up to 120 years. This prediction has been confirmed by longevity record held by a French woman, named Jeanne Calment, who lived for 122 years. For an ultimate test to determine if Schisandrin B, which may mitigate mitochondrial decay, can extend lifespan, a longevity study was conducted using mice. Experimental result indicated that dietary supplementation of Schisandrin B improved the survival of both male and female mice. In conclusion, Schisandrin B, which can preserve the structural and functional integrity of mitochondria, the cell origin of Qi, may help prevent, or at least delay, the onset of age-associated diseases, and thus favor a long and healthy lifespan.