Continuing the discussion from The Real Problems With Soylent Are Not Fixed In Version 1.1:
I finally had time to read the study, and I don’t think it’s as strong or clear as these quotes from the abstract imply.
As always, the usual caveat applies that a single study can only IMPLY something, not conclude it… and so far, this is the only study I know of finding an estrogenic effect from soy lecithin.
They were apparently the first to use the YES method (genetically engineered yeast with human genes in them) to evaluate the estrogenicty of soy lecithin, because they note that they could find no standard extraction method in the literature, (they decided to extract with acetone.) They weren’t able to find any known estrogenic soy isoflavone in the extract, but they did see the GMO yeast react as if there were an estrogenic comound, prompting them to speculate, “a so-far unidentified estrogenlike compound is present in soy lecithin. Whether this chemical is of soy origin or is a contamination during production remains to be answered.”
I’d like to see confirmational studies, perhaps using a different extraction method or discussing/confirming the validity of the method, confirming that this is not a false positive from the yeast (always a risk with a reaction to an “unknown.”), and I’d like to see different soy lecithin sources - they did not use a commercial food lecithin source, but rather, two different brands soy lecithin sold as supplements that they picked up on a spur of the moment in “local drug stores.” Lastly, I’d like to see this done with other, non-soy lecithin sources - sunflower lecithin, chicken yolk or other animal lecithin. If soy lecithin is estrogenic, but it contains no soy isoflavones, it’s reasonable that lecithin, itself, may be estrogenic - and we may have the exact same result from all vegetable sources of lecithin, or even from animal sources of lecithin.
The food product in the study of most interest to us in the liquid food community were five types of cow’s-milk based infant formula. Of the five formulas, the first three contained lecithin, and the last two did not. They got estrogenic responses as shown in the following chart:
Because F1 and F3, which contain soy lecithin, were so much higher than F5, which had no soy lecithin, they wanted to look into whether lecithin was causing the spike - that’s why they picked up the supplements from the drug store to test, in the first place. But note also how high F4 is, which has no soy lecithin… and note that the LOWEST estrogenicity was from F2, which did, in fact, have soy lecithin. It’s not unlikely, to me, that we’re seeing the effects of variability in the amount of residual hormonal compounds in another ingredient - the cow’s milk.
Lastly, the estrogen equivalency levels they got from these infant formulas, which, like Soylent, probably use the lecithin as an emulsifier, never got as high as 25. for comparison, most of the cheeses they tested scored higher than the infant formulas (as high as 40). One of the authors’ main comments was, “we conclude that dietary estrogens are omnipresent and not limited to soy-based food.” For reference and perspective, three different tofu they tested all scored in the range of 1,000. Not only is soy lecithin in a drink less estrogenic than tofu, it’s apparently less estrogenic than cheese.
As usual, the first study noticing an interesting effect is not conclusive - it’s suggestive, and we really need more work done before we draw any conclusions - much less use them to start making changes in daily practice. Even if lecithin is, in fact, found to have an estrogenic effect, the size that we get from the low quantities used for emulsification don’t look like cause for alarm, just yet.