Soy lecithin is one of the most ubiquitous additives in our food supply. It’s used primarily as an emulsifier, and you can find it in everything from salad dressing to tea bags. Paleo dieters avoid the brunt of it by eliminating most processed foods, but it almost always pops up in chocolate (everyone’s favorite honorary Paleo food) and often appears in supplements.
I recommend avoiding soy as a general rule, but consuming small amounts of soy lecithin as an additive is very different from, say, eating a soy burger topped with soy cheese or drizzling soybean oil on your salad. This article will probably be more than you ever wanted to know about soy lecithin, but I wanted to do my best to get all the facts out on the table.
What is Soy Lecithin?
The term ‘lecithin’ can have different meanings depending on the context, but for our purposes, it refers to a mixture of phospholipids and oil. Phospholipids are a component of the cell membrane in all plants and animals, but lecithin is most often derived from sunflower kernels, rapeseed (canola), milk, soy, and egg yolks. (1)
The specific composition of soy lecithin varies depending on its manufacturer and intended use, but on average, it contains about 35% soybean oil and 16% phosphatidylcholine. (2) Phosphatidylcholine is a type of phospholipid that is abundant in liver and egg yolks, and is the primary form of choline found in foods. (3) The remaining percentage is other phospholipids and glycolipids.
To make soy lecithin, soybean oil is extracted from the raw soybeans using a chemical solvent (usually hexane). (4) Then, the crude soy oil goes through a ‘degumming’ process, wherein water is mixed thoroughly with the soy oil until the lecithin becomes hydrated and separates from the oil. Then, the lecithin is dried and occasionally bleached using hydrogen peroxide.
There are many claims online about soy lecithin being full of nasty chemicals left over from the production process. Not surprisingly, there aren’t many credible sources describing the chemical content of commercial soy lecithin, but I have found some relevant data about the safety of soy lecithin.
Before the ‘degumming’ step where lecithin is removed, the crude oil undergoes a multi-step process to remove the hexane. (5) However, it appears that the FDA doesn’t regulate the amount of hexane residue in food products, and one paper estimated that the residual hexane concentration of soy oil is 500-1000ppm. (6) So, it’s very possible that similar concentrations remain in the soy lecithin. (For comparison’s sake, the concentration limit for hexane in pharmaceuticals is 290ppm.) (7)
According to one analysis, total pesticide residues in crude soy oil are around 400ppb. (8) Since the pesticide concentration of the oil after degumming is similar, it’s pretty likely that some of those pesticides end up in the lecithin as well.
While it’s unfortunate that soy lecithin likely contains pesticides and solvents, I would just encourage you to keep this information in perspective. We’re exposed to hundreds of chemical toxins every day in our air, water, household products, and food, and contaminants in soy lecithin will contribute only slightly to your overall toxic load. After all, we’re talking parts per million and parts per billion, and soy lecithin itself usually makes up no more than 1% of processed foods. (9)
Of course, in an ideal world, we would be able to avoid these things altogether, and I certainly recommend reducing your exposure as much as possible. It’s also a good idea to make sure your detox systems are functioning effectively. But unless you have a severe chemical sensitivity to hexane or pesticides, occasionally consuming small amounts is not worth getting bent out of shape over.
Soy allergies are triggered by soy proteins, so whether lecithin triggers an allergic response or not depends on its protein content. One analysis found protein concentrations ranging from 100 to 1,400ppm in six different soy lecithin samples. (10) (For reference, the new FDA gluten-free labeling law requires a gluten concentration of less than 20ppm.) (11) Another analysis of six different lecithin samples found that four had sufficient protein to trigger an IgE-mediated response in people with soy allergies, while two contained no detectable protein at all. (12) However, another study performed similar testing and concluded that even if protein is present in soy lecithin, it’s not a significant allergen for people with soybean allergies. (13)
It’s clear that the source of the soy lecithin is a major determinant in whether or not it will present a problem for those with soy allergies, but if you have a soy allergy, I’d say better safe than sorry. However, because protein is present in such a low concentration, and soy lecithin itself usually makes up no more than 1% of processed foods, it’s probably not a problem for those with minor sensitivities to soy.
Most of the soy grown in the US is genetically modified, so unless the label says ‘organic soy lecithin,’ it probably came from a genetically modified soybean. You know I’m not a fan of GMOs, due to the presence of potentially transferrable DNA and potentially immunogenic proteins. However, as I discussed in the section on allergies, soy lecithin contains very little soy protein, and lecithin from some sources contains no detectable protein at all. Soy lecithin also contains very little DNA, and the DNA present is usually degraded to the extent that it’s impossible to tell whether the soy is genetically modified or not. (14) Thus, most of the risks associated with consumption of GMOs aren’t relevant for soy lecithin, and shouldn’t be cause for concern.
Soy is the greatest food source of phytoestrogens, and one group of researchers discovered significant estrogenic activity in soy lecithin. (15) Interestingly, none of the soy lecithin they tested contained genistein, which is the predominant phytoestrogen in soy. They concluded that “a so-far unidentified estrogen-like compound” is present in soy lecithin that accounts for its estrogenic activity.
We know how problematic phytoestrogens can be, but again, the dose makes the poison. Remember, soy isn’t the only source of phytoestrogens we’re exposed to. (Did you know that flaxseed is also a significant source of phytoestrogens? In fact, one study showed that supplementation with ground flaxseed altered estrogen metabolism even more than supplementation with soy flour.) It’s definitely best to keep phytoestrogens to a minimum, and individuals dealing with cancer or fertility problems might want to avoid them more strictly. But for most generally healthy people, the small amounts of phytoestrogens from soy lecithin shouldn’t be a problem.
One study that has been used widely as ammunition against soy lecithin is titled “Effects of a Commercial Soy Lecithin Preparation on Development of Sensorimotor Behavior and Brain Biochemistry in the Rat.” Researchers found that soy lecithin in concentrations of 2% and 5% in the diets of pregnant and newborn rats resulted in impaired reflexes and swimming ability, along with other cognitive deficiencies.
It’s important to understand that these effects are due to choline toxicity, not soy lecithin per se. The elevated brain/body weight ratios, plus elevated acetylcholine and choline acetyltransferase levels that resulted from soy lecithin supplementation were caused by the phosphatidylcholine, and would’ve still occurred even if they had used a source of phosphatidylcholine other than soy; even egg yolks.
It would be very difficult to consume as much choline as these rats did, especially from soy lecithin. In fact, most people are deficient in choline! This is just another case of a study being misinterpreted, and you certainly don’t need to worry about soy lecithin causing developmental problems.
I believe I’ve covered all of the main concerns about soy lecithin, but it’s worth mentioning that soy lecithin is also being recommended and consumed as a dietary supplement. There is a growing body of research supporting its use for improving blood lipids, reducing inflammation, and treating neurological disorders. (16) For instance, one study found that after 2 months of supplementing with 500mg of soy lecithin per day, total cholesterol levels fell by 42% and LDL levels decreased by 56%. (17)
However, most of these studies involve supplementation with a purified form of soy lecithin, which usually contains less soy oil and more phosphatidylcholine than the commercial soy lecithin that shows up in foods. Additionally, isolated phosphatidylcholine is often referred to as ‘lecithin’ in scientific contexts, so some studies supplementing with ‘soy lecithin’ are really just supplementing with phosphatidylcholine.
So once again, it’s not the soy lecithin; it’s the choline. Luckily, you can derive all the benefits of phosphatidylcholine supplementation just by increasing your consumption of choline-rich foods like egg yolks and liver.
So, what to do?
The only people who need to make a point of avoiding soy lecithin are those with severe soy allergies or chemical sensitivities, and of course, those who notice that they personally react badly to it. And if you don’t have a soy allergy, almost all of the remaining concerns about soy lecithin (pesticides, solvents, and GMOs) can be completely eliminated by purchasing products that contain organic soy lecithin.
But for the vast majority of the population, even conventional soy lecithin isn’t worth worrying about one way or the other. If it’s just as easy for you to avoid it as it is to consume it, then do so. (For example, Enjoy Life is one popular brand of chocolate that is soy-free.) Ultimately, I think most people can just enjoy their occasional chocolate treat without worrying about whether it contains soy lecithin.