The max you want daily form supplements and diet combined is 2000 mgs a day. Most people should get at least 1000 mgs a day.For diarrhea control the most common pattern is 1/2 to 1 tablet with each meal (so 3X 300 or 900 mgs or 3X 600 for 1800 mgs) A lot of IBS-Ders don't eat much in the way of high calcium foods like dairy, so can take a fair amount from supplements.K.