Saponins are natural detergents that are found in certain desert plants and are also present in small amounts within some pod family foods. The major commercial sources of Saponins are Yucca Schidigera, which grows in the arid Mexican desert country of Baja California.
Yucca Saponins, and other components of Yucca as well, have ammonia-binding activity. When ammonia is processed by the liver, uric acid is created. When added to the diet, Yucca Saponins pass the ammonia through the digestive tract unabsorbed and are then excreted in the faeces. Yucca is also used in some dog foods to reduce the odour in their urine and bowel movements.
Saponins bind with cholesterol, which has many important considerations including cholesterol-lowering activity in humans. Saponins react with cholesterol in the protozoal cell membrane by causing the cell to rupture. Research currently in progress at Agriculture Canada in Lethbridge, Alberta has shown Yucca extract to be very effective in killing giardia trophozoites, which are the infective stages released in the gut when the oocytes, or eggs, sporulate. Yucca Saponins are also effective in killing rumen protozoa (helps breed Salmonella bacteria) when ingested.
The blood cholesterol-lowering properties of dietary Saponins are of interest in human nutrition. One research program on this subject was that of Dr. Rene Malinow at the Oregon Regional Primate Center, whose research (published in the American Journal of Clinical Nutrition in 1997) demonstrated unequivocally the cholesterol-lowering properties of Saponins. This desirable effect is achieved by the binding of bile acids and cholesterol by Saponins. Bile acids form mixed micelles (molecular aggregates) with cholesterol further increasing its absorption. Cholesterol is continually secreted into the intestine via the bile, with much of it subsequently reabsorbed. Saponins cause a depletion of body cholesterol by preventing its re-absorption, thus increasing its excretion in much the same way as other cholesterol-lowering drugs do.
Although there are reports of the development of synthetic Saponins as drugs for treating high blood cholesterol, Yucca / Saponins are natural phytochemicals currently used in foods and beverages and herbal products and are safer. Recent research conducted in Canada and Africa have suggested that the very low serum cholesterol levels of tribes in East Africa, who consume a diet very high in animal products, cholesterol, and saturated fat, are likely due to the consumption of Saponin-rich herbs like Yucca.
The binding of bile acids by Saponins has other important factors. Bile acids excreted in the bile are metabolized by bacteria in the colon, producing secondary bile acids. Some of the secondary bile acids are promoters of colon cancer. Saponins binding to primary bile acids reduce the formation of these secondary bile acids thus helping to prevent colon cancer. The University of Toronto has shown that feeding Saponins to laboratory animals reduced the number of pre-cancer colon lesions in mice. The Canadian researchers also found that Saponins had a dose-dependent inhibitory effect on growth of human carcinoma cells in culture. Major current interest in Saponins concerns their effects on the immune system.
Yucca is a rich storehouse of phytochemicals with many useful and important functions in human and animal nutrition.