@joha, the GI symptoms you are enduring may have a basis in a deficiency of vitamin B1. Vitamin B1 (thiamine) needs adequate magnesium to become bioactive as does vitamin D. Activated thiamine in turn is needed to activate vitamin B6. The B vitamins work better together. Thiamine can be diminished or destroyed by heat from long cooking times and by anti thiamine factors listed in the stuttersence link. Deficiencies may not respond to low levels of supplemental thiamine and instead require higher levels as explained in the third eonutrition link. The first two links offer information on thiamine's role in the gut the last link is a overview of thiamine. Always consult your health care professional before using any supplement.
https://www.eonutrition.co.uk/post/when-sibo-ibs-constipation-are-just-unrecognized-thiamine-deficiency
https://www.eonutrition.co.uk/post/thiamine-deficiency-a-major-cause-of-sibo
http://stuttersense.blogspot.com/2014/08/these-factors-reduce-your-thiamine.html
https://www.eonutrition.co.uk/post/mega-dose-thiamine-beyond-addressing-deficiency
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8533683/