Legal status and toxicity of saponins
Abstract
Saponins occur in at least 400 plant species belonging to 60 different families. Some of these plants such as spinach, beetroot and asparagus are components of the human diet whilst others are animal foods. Because of their foaming properties saponins are used in the manufacture of foods, beverages, toilet preparations and pharmaceuticals. Several plant extracts used as flavouring agents in food contain active saponins.
There is no legislation in the UK or USA controlling the use of foaming agents as a class in the manufacture of foods. The use of saponins as foaming agents is specifically prohibited in some countries, particularly in Central and Southern America. Flavouring legislation has yet to be formulated in the UK; in the USA several plant extracts containing saponins including quillaia (from Quillaja saponaria Molina), are permitted as flavourings, whilst in Federal Germany quillaja bark is specifically prohibited.
There is some variation in the toxicity of saponins from different sources. Most toxicity tests have been with single doses administered orally or by intravenous injection. The lethal oral dose is 3–1000 times as great as the lethal intravenous dose. The majority of saponins are powerful haemolytics in vitro but large doses are needed to produce haemolysis on intravenous injection. Several authors have studied the effect of saponins on growth but no references have been found to experimental work on the chronic effects of those saponins likely to be consumed by man in the diet. However, a guide to the safety of some saponins is provided by experience based on common use as food additives or natural components of foods.