I don't consider it to be that common. You will see it primarily in people with low intestinal flora, and in cases of inflammatory bowel conditions such as Crohn's and ulcerative colitis. None of these are that common.
Does l glutamine really fix the gut and at what dosage? thanks for all your great info.
I think it depends a lot on the cause. The most common cause is a lack of intestinal flora. In this case it would not have any real effect. With inflammatory bowel disorders it can help with healing. In these cases I recommend 500-1000mg 3 times daily at least 30 minutes before meals. But I would not rely soley on glutamine for the healing. There are other factors to be addresed such as the bacteria triggering the problem and the adrenal dysfunction.
Primary focus for non-autoimmune leaky gut would be reestablishing the flora with probioitcs and prebiotics.