In a discussion on Facebook, someone asked if soy lecithin was safe. A commenter claimed that soy lecithin was harmful to gut health. Let's take a look at the body of evidence to find out: is soy lecithin inflammatory?
What is Lecithin?
Lecithin is the naturally-occurring substance in eggs that give egg yolks their emulsifying properties. That’s why we use eggs in baking and in making salad dressings because it's able to combine water and oil. Lecithin is also found in soy, sunflower, meats, and other foods. Lecithin is an oily substance made up of phospholipids, glycolipids, triglycerides, phosphatidylcholines, phosphatidylethanolamines, and phosphatidylinositols. (Source)
Is Soy Lecithin Harmful to Gut Health?
The study that started this whole discussion online is called Direct impact of commonly used dietary emulsifiers on human gut microbiota. The person that commented with this article claimed that soy lecithin was found in this study to negatively impact gut health and is inflammatory.
However, reading through the study I couldn't find any evidence of this conclusion. The study actually said that the impact of soy lecithin on the intestinal environment were indiscernible.
The commenter was so adamant about it being inflammatory, even though they weren't providing clear evidence, I decided to research further. Maybe I was missing something.
I found a grant was issued from 2019 - 2022 called the FADiet study. The funding was supposed to look at the impact of lecithin on the gut. Other results came from the grant funding but we never got the data it promised on the impacts of lecithin on the gut. A dead end.
Then, I started running on to studies on fish and lecithin. A few studies found that adding soy lecithin to the diet of fish improved their gut health and reduced inflammatory markers. (Source)(Source)
I found a study on mice that found soy lecithin may increase the level of IL-10, an anti-inflammatory cytokine, and can support gut health. (Source) Interleukin 10 is critical to reduce intestinal inflammation. (Source) Another study found that a combination of selenium and lecithin reduced gut inflammation in mice. (Source) Lecthin on its own also had a protective effect against alcohol-induced inflammation, just not as pronounced as lecithin combined with selenium.
This study found that lecithin improved gut health in mice fed an inflammatory high-fat diet. (Source)
Of course, we're not fish or mice. Were there any human studies?
Finally I started finding some. In this study, researchers were developing a probiotic encapsulated with sunflower lecithin. it was found to treat diarrhea and improved gut health. (Source)
The mucin of the gut is largely comprised of phospholipids (same as lecithin) so the addition of phospholipids to the diet could improve intestinal health and are being studied as a treatment for colitis. (Source)
Does Soy Lecithin Have Other Benefits?
Lecithin (from all sources) due to its ability to emulsify water and oil, is able to help the body absorb and utilize oil-soluble vitamins like vitamin E and vitamin A. (Source)
Lecithin is also a good source of choline, a nutrient that the brain and nervous system need to regulate memory, mood, muscle control, and other functions. And to form cell membranes. (Source) Choline has also been found to reduce alcohol-induced brain inflammation. (Source) Other studies have found lecithin/choline to have neuroprotective effects. (Source)(Source) Lecithin is part of the MIND diet, a diet designed to prevent dementia in Alzheimer’s. This diet has been found to delay cognitive decline. (Source)
One mouse study found that soy lecithin helped in treating liver damage. (Source) Soy lecithin combined with a vitamin B complex was able to reduce alcohol-induced liver inflammation. (Source) Lecithin alone (without the vitamin B) also had anti-inflammatory benefits, just not as pronounced as when combined with the B vitamins.
Lecithin may also provide cardiovascular and metabolism benefits:
“Vegetable lecithins provide food-derived PL [phospholipids] that, similarly to endogenous PL, have the potential to modulate numerous membrane-dependent cellular functions, as well as exert lipid regulating, anti-inflammatory and antioxidant effects. Despite the lack of converging evidence concerning their effects on lipid digestion and intestinal absorption, it is clear that dietary vegetable lecithin exert an overall beneficial effect on lipid and lipoprotein metabolism. In this way, they have been proposed as novel therapeutic agents for the treatment of hyperlipidaemia associated with metabolic and cardiovascular diseases. Supporting this idea is the fact that PL are capable of forming unique lipid droplets, referred to as liposomes, which have been investigated as drug carriers for decades and which have been associated with ameliorated blood and hepatic lipid profiles [119].” (Source)
Is Soy Lecithin Estrogenic?
Another common comment on the facebook discussion was "soy is estrogenic, AVOID!" So, I thought I'd address this claim as well.
A 2011 study purported that soy lecithin is "strongly estrogenic" according to a yeast assay. (Source) However, the conclusion is questionable, as they did not test the actual lecithin, but made an extract of the lecithin.
"Due to its low solubility, lecithin was not analyzed as a whole but needed to be extracted. Soy lecithin is a mixture of different phosphatidylcholines of which at least 97% are not dissolvable in acetone. To remove these, we developed an acetone-based extraction as there was no suitable method described in the literature. One gram lecithin was added to 20 mL acetone, mixed, and sonicated for 10 min. Then, the mixture was centrifuged at 3600 rpm for 12 min. The supernatant was evaporated under a gentle N2 flow and redissolved in 4 mL methanol. Extracts were immediately analyzed in the YES."
So, in other words, they got rid of 97% of the lecithin and analyzed this extract for estrogenic activity. The test came out "strongly estrogenic" as no surprise. Soy lecithin contains a small amount of phytoestrogenic compounds called isoflavones, which are likely what they extracted in the acetone. To say, though, that soy lecithin as a whole is "strongly estrogenic" would be false, as it was only the specific extract that they tested. Of course it came out estrogenic - they isolated the isoflavones.
Soy lecithin does contain a small amount soy phytoestrogens which are controversial in nature. (Although many studies point to their benefits, that's a different article for a different day.) Below is a chart of isoflavone content in common soy foods. As you can see, the isoflavone content of soy lecithin is quite low compared to other soy products. Add to the fact that lecithin in a food product is usually going to be 5% of the recipe or less, the amount of actual isoflavones you'd ingest from a food containing soy lecithin would be dietarily irrelevant.
Is Soy Lecithin Safe?
The bottom line: lecithin is naturally-occurring in many foods, supplies nutrients that our bodies need, and aids in oil-soluble vitamin absorption. There is no evidence to suggest that soy lecithin is inflammatory. Additionally it has been found to have anti-inflammatory effects in metabolism and benefits to brain health. Certainly one can have too much of it, just like anything. And added lecithins are typically associated with highly processed foods. Limiting our intake of processed foods is optimal, but we should not fear conservative intake of lecithin as part of a healthy, antioxidant-rich diet.
