Octasa is an interesting one, and I assume you are taking 4.8 grams daily?
Considered a high-magnesium diet instead? Include at least 400 mg of Magnesium daily for a high magnesium diet. The best sources of magnesium are dark green vegetables, legumes, cereals, wheat bread, fish, and nuts.
/www.cedars-sinai.edu/Patients/Programs-and-Services/Documents/CP0403MagnesiumRichFoods.pdf