Because consumption of the L. reuteri yogurt made with the ATCC PTA 6475 and DSM 17938 strains work by raising levels of oxytocin (in addition to local probiotic benefits on reducing H. pylori and acid reflux, for example, unusual for its upper, not just lower, gastrointestinal benefits), there are people who probably should not consume the yogurt.
Oxytocin is a multi-faceted hormone whose levels decline as we age, much as does growth hormone and other hormones. But, among its many varied effects is the potential for causing uterine contraction. That is why oxytocin is administered to provoke delivery of a term infant: it provokes uterine contraction to deliver the baby along with cervical relaxation. There are experimental non-human and yet unpublished data that suggest that oxytocin may raise estrogen levels in females. But, because of these potential uterine and estrogenic effects, there are people who probably should not eat the yogurt that boosts oxytocin. This includes:
- Pregnant mothers
- Women younger than age 45
- Women with a history of estrogen receptor-positive breast cancer
- Women with active endometriosis
- Women who are still experiencing menstrual cycles
The last item, menstruating women, is to avoid making menstrual cramps worse, i.e., amplifying the intensity of uterine contractions. (Interestingly, a couple of women taking the yogurt but still experiencing menses actually reported dramatic reduction in menstrual cramps, but that is insufficient evidence.)
That said, oxytocin when administered intranasally or injected, even at many times physiologic doses, has a long track record of safety with virtually no side-effects reported beyond occasional reports of excessive emotionality (e.g., crying too much at movies). So these are just precautions as we all embark on this fascinating adventure of boosting oxytocin levels, given its extraordinary youth-preserving potential that is being played out in experimental evidence and now increasingly in human evidence.