I've been taking 1000mg of magnesium per day to help with constipation. Constipation has been an on and off problem for my entire life, exacerbated by going paleo; before, I was eating basically a raw vegan diet consisting of a lot more roughage. Since the overall volume of my stools has decreased, I've become blocked up for as many as 5 days at a time.
Thanks to Paleohacks, I sought out a magnesium oxide supplement. It's been a small but sufficient help in this department. However, lately it seems like I have to take more and more to stay regular (regular for me means once per 2 or 3 days -- not great, but manageable). As I've dealt with constipation my whole life, with whatever fix, I'm wary of the dreaded word "dependency." With my understanding, magnesium draws water into your intestines, increasing the amount of stool and the ease of passing it. I suspect that with this unnatural supplementation, my colon may be getting used to the extra help and thus not working as hard in peristalsis. Am I just being paranoid? What's a safe upper limit to magnesium supplementation?