Experts recommend that healthy adults eat 20 to 35 grams of dietary fiber per day. You can meet this goal by eating a well-balanced diet containing a variety of foods, such as fruits, vegetables, and whole grain bread, cereal, pasta, rice or crackers.

Additional Resources:

http://edis.ifas.ufl.edu/pdffiles/HE/HE69700.pdf
http://www.wholegrainscouncil.org/whole-grains-101/how-much-is-enough