I have no difficulty whatsoever getting 30 grams of fiber a day from the normal "American" foods that I eat. Every single day. And no supplements. Beans, citrus fruits, vegetables, whole grains, dried fruits and many other foods contain fiber. Here's a pretty reasonable meal plan for one day, including one snack:
A large serving of oatmeal with raisins for breakfast is 5 grams. Eat a piece of WW toast with it and that's 2 more grams. Have a sandwich at lunch and that's about 5 grams for just the 2 slices of WW bread. A bowl of chili beans with your sandwich is 5 more grams. One serving of pinto beans at dinner is 6 grams. Add some brown rice for 3 grams and a serving of broccoli for 2 more. Enjoy a snack of popcorn for another 2 grams.
Count it up 2legit. That's 30 grams, easy as pie. It is normal nutritious and delicious food. You learn how to amke it in a cookbook, not a science book. And I easily could have gotten even more fiber with a salad, some tomato on the sandwich, a spoon of bran in the oatmeal, etc., etc. Anybody in America could eat like this every day and enjoy it.
How come you can only get 15 grams in your diet? How come you have to get the other 15 from expensive nasty supplements. In 7 years of studying nutrition you should have learned more about real food. How come you can't link us to the peer reviewed journal articles that tell akarius why he has to eat some supplement exactly 10 minutes before he eats real food? In 7 years of studying you should have learned more about science too.