Effective in treating occasional constipation and restoring regularity. Fiber Supplement: each serving adds 3 grams of fiber to your diet. For lowering cholesterol to promote heart health. Diets low in saturated fat and cholesterol that include 7 grams of soluble fiber per day from psyllium husk, as in Metamucil, may reduce the risk of hearth disease by lowering cholesterol. One adult dose of Metamucil has 2.4 grams of this soluble fiber.