Paleo proponents list ‘saponins’ in legumes as one of the reasons why we shouldn’t eat them. Wow! As a herbalist, saponins are one of my favourite herbal constituents. You can’t select one single action a plant-chemical possesses and then conclude that this one action sums up the entire purpose and existence of this plant chemical as a whole. Crazy stuff!
Saponins are part of many plant’s immune systems, protecting them from insects, predictors and fungal infections. I love the fact that the presence of saponins can often be identified without any lab equipment, simply by adding water and agitating: if soapy bubbles appear, you have saponins! We used to have a wattle tree outside containing saponins and in the wet season our pavers would get a fantastic wash-down from the combination of rain with fallen saponin-containing leaves.
Saponins enhance the solubility of various other constituents (plant ingredients), thereby acting as emulsifiers in herbal concoctions, so that oily and watery constituents combine better in the same medium. Aside from legumes, saponins are found in plentiful supply in quinoa, garlic and onions.
There are many different kinds of saponins, but they can generally be grouped into steroidal saponins or triterpenoid saponins.
Many adaptogenic herbs and sexual/hormonal tonic herbs contain steroidal saponins (e.g. wild yam and panax ginseng). Adaptogenic herbs are herbs that helps us adapt to stresses on all levels : mental, emotional, physical, environmental (e.g. temperature change). Steroidal saponins are often found in herbs that are used as tonics for vitality and longevity, and herbs that treat arthritis, so why on earth would we want to avoid saponin containing foods like legumes?!!
The longest living people on the planet embrace legumes rather than avoiding them. In Dan Buettner’s book Blue Zone Project, written about the longest living communities and cultures around the world, we find this telling quote: “They asked centenarians what they ate and heard ‘beans, rice, tortillas and fruit’ over and over.”
Herbs that contain triterpenoid saponins (e.g. siberian ginseng and liquorice) are often anti-inflammatory, anti-carcinogenic and vascular toning. A good example of the latter is horse chestnut, whose saponins combine with coumarins to strengthen our veins and lymphatic vessels. Looking at the saponin ‘glycyrrhizin’ in liquorice, we find that it is anti-inflammatory, immuno-stimulating, anti-viral, adaptogenic and hepatoprotective (protects the liver). The triterpenoid saponins in siberian ginseng improve our stamina, resistance to stress and may even have neuroprotective and neuroregenerative properties that could play a role in preventing or slowing neurological damage.
So where does the bad press come from? Is it because saponins are highly toxic and can destroy blood cells when injected, or because they are poisonous for many cold-blooded animals? Luckily, we aren’t cold-blooded and most of us are smart enough to eat rather than inject our saponins, which renders the vast majority of saponins completely harmless to us as humans. Yes, large amounts can irritate the digestive system and there are a few saponins that can be toxic to mammals, but these are rare, and certainly no reason to avoid them altogether given their fantastic health-giving effects.
I’ve witnessed a herbally induced saponin-overdose first-hand and I would rather not witness that again, but the reality is that very few of us would ever be exposed to saponin excess, partly because of the way we prepare our foods and the digestive process itself. Just because something is toxic in large amounts doesn’t mean it isn’t beneficial in small amounts, and visa versa. As per the Arnold-Schultz law, what can inhibit or kill at large doses can become a therapeutic stimulant in small doses and it’s my firm belief that our natural daily exposure to dietary saponins rarely exceeds this small therapeutic dose.