You’re absolutely right to be skeptical about swapping one lecithin for another just based on anecdotes-there just isn’t robust clinical data directly comparing sunflower and soy lecithin for plugged ducts. What’s frustrating is most of the recommendations floating around are drawn from user experiences and a patchwork of small studies on lecithin in general, usually without hydrating the differences in source. There’s even less out there about ideal doses or onset of action; most sources-often lactation consultants-suggest anywhere from 1,200–4,800 mg per day, but that’s not tailored to lecithin type.
On allergenicity: soy is obviously not ideal for those with soy allergies, and while sunflower allergies are rare, they’re not unheard of (look up some food allergy case reports). On the flip, sunflower lecithin is non-GMO by default and often favored by folks trying to avoid soy for hormonal or allergenic reasons. But without head-to-head safety or long-term infant outcome data, claims that one is categorically “safer” aren’t evidence-based right now.
Bottom line: we really need controlled trials. Until then, any switch or dosing should be considered a calculated experiment, not an evidence-backed protocol. If anyone spots newer studies beyond the usual case reports or general breastfeeding guidelines, I’d love a link.