I have been making and eating kefir for about 10 days from some grains a friend gave me and have noticed that my constipation has returned. Normally I keep this well under control by eating linseeds and lots of salad and veg (except onion family which I can’t tolerate) and limiting bread and anything sweet. Apart from starting on kefir nothing else has changed.
Has anyone else experienced this? Should I give up on kefir?

Kefir can quite radically effect your microbiome. If there is a clear cause-and-effect then you have your answer. Options are: reduce the quantity of Kefir you drink and build up slowly; stop completely and see how well you do with other fermented foods; and/or order some INULIN powder and see if that solves the problem. Good luck! Graham