What Are Saponins and Are They Actually Bad for You?

In your effort to eat a more plant-based diet, you may have stumbled upon claims that saponins — phytochemicals found in many plants — can cause a host of harmful side effects, such as intestinal damage and inflammation.

But is there enough evidence to confirm the risks of saponins? Not quite, experts say.

In fact, these plant compounds can have benefits for your overall diet, and cutting them out may do more harm than good. Here's everything you need to know about what saponins are, what the claimed risks of saponins are and the benefits of saponins.

Think of saponins as bodyguards for plants: These phytochemicals help to keep plants healthy, and they can do the same for you.

"Saponins are made by plants as a defense mechanism to protect themselves against infections and pests," says DJ Blatner, RDN, author of ‌The Superfood Swap.‌

They can be found in more than 100 families of foods, Blatner says. The most common are:

• Legumes
  • Soybeans
  • Dried peas
  • Beans
  • Lentils
  • Chickpeas
• Quinoa
• Oats
• Asparagus
• Spinach
• Onion
• Garlic
• Yams

The Latin word "sapo" — which means "soap" — inspired the term "saponin," per a July 2017 peer-reviewed chapter in ‌Application and Characterization of Surfactants‌. That's because saponins have the unique properties of foaming and emulsifying agents (for instance, the bubbly aquafaba in a can of chickpeas is filled with saponins). Traditionally, saponins have been used as natural detergents.

Saponins are known to be toxic to insects, parasite worms, mollusks (think snails) and fish, per the chapter. However, that toxicity doesn't necessarily carry over to warm-blooded animals: Studies in rats, mice and rabbits have implied that saponins don't get absorbed in the gastrointestinal tract, but rather are broken down by enzymes. Saponins also have antifungal, antiviral and antibacterial activity.

These phytonutrients have earned the reputation of being an "anti-nutrient" because they affect the absorption of certain nutrients in your body — but that doesn't mean they're unhealthy or need to be cut out of your diet.

"Saponins get bad press as an anti-nutrient because they may bind to certain minerals like iron, calcium and zinc and make them less likely to get absorbed," Blatner says. "However, saponins have actually been shown to have potential health benefits such as lowering cholesterol, blood glucose and cancer risk." (The key word here is ‌potential‌ — saponins haven't been clinically proven to possess these perks.)

In fact, by cutting saponins out of your diet, you could do more harm than good. Saponins are in a wide variety of foods that provide fiber and other nutrients necessary for a healthy and long life.

"When looking at the big picture, completely eliminating these foods could prevent you from getting great nutrition like plant-based protein, fiber and micronutrients," says dietitian Amanda Kostro Miller, RD. "It's a situation where the benefits of these foods usually outweigh the risks of not eating them."

However, while it may give you some peace of mind, there likely isn't any reason for you to need to do so.

"There is no good evidence to suggest saponins are harmful in any way," says dietitian Morgyn Clair, RDN. "It is possible that in very concentrated amounts and very large doses, saponins could cause some intestinal damage. However, it's unlikely anyone would consume saponins in this way."

There is also no evidence of saponins negatively affecting the absorption of any specific nutrient in ways that make them necessary for the average person to avoid, Clair adds.

If you're at high risk for a disease related to mineral deficiencies, like anemia with iron deficiency or osteoporosis with calcium deficiency, ask your doctor if you need to monitor your food choices for anti-nutrient content, per Harvard T.H. Chan School of Public Health. Anti-nutrients may include saponins, but also those such as tannins (found in tea, coffee and legumes), phytates (found in whole grains, seeds, legumes and nuts) and glucosinolates (found in cruciferous vegetables like broccoli and cabbage).

As many nutrients have anti-cancer and antioxidant properties, avoiding them entirely is not recommended, per the university.

That said, if you're ‌sensitive or allergic‌ to saponins, your doctor may recommend you limit them — as you would with other types of food sensitivities or allergies.

While more research is needed, evidence points to various benefits of saponins in the diet.

"There are numerous reported benefits of saponins, but one of the most widely studied is their antioxidant capabilities," Clair says. "These plant chemicals are able to help eradicate free radical damage in the body."

Saponins have also been found to have a cholesterol-lowering effect in humans, per an April 2017 review in ‌Food Chemistry‌‌.‌ The researchers note that saponins are important in reducing the risk of many chronic diseases.

A high-saponin diet may even help prevent cavities, and in epidemiological studies, saponins have been shown to be inversely associated with kidney stones, per a classic July 2004 study in the ‌Journal of Medicinal Food‌‌.‌

"Also, avoiding foods that contain saponins could make you miss out on really healthy, plant-based nutrition and other benefits," Kostro Miller says.

In other words, perhaps one of the greatest benefits of saponins is the foods they're found in, which make up a healthy plant-based diet. Researchers analyzed data from over 12,168 middle-aged adults who were followed from 1987 through 2016 to track the effect of diet on long-term health in an August 2019 study in the ‌Journal of the American Heart Association‌.

Those who adhered to a plant-based diet or pro-vegetarian diet best had:

• 16 percent lower risk of heart disease
• 31 to 32 percent lower risk of heart disease mortality
• 18 to 25 percent lower risk of all-cause mortality

The key to a healthy diet is variety, and including saponin-rich foods in your meals ensures you can access a wide range of nutrients.