Are there any combinations that make sense if I choose to switch to a more high fiber, plant-based diet with less processed foods?

Sure, here are a few combinations to consider:

Increase fiber, Increase fluids. Insoluble fiber from fruits, vegetables, grains, and other plant-based foods help the bowel regulate waste disposal from the body. Since fiber absorbs water in the colon, it is necessary to consume adequate amounts of fluids to reduce the possibility of constipation.
Meat, bran and iron. Phytates are antioxidants found in grains, nuts, legumes and rice and in large quantities of bran. The phytates in bran inhibit iron absorption from meat, but this improves with the addition of vitamin C. So it’s a good idea to serve up your steak and rice meal with broccoli for added vitamin C.
Iron and vitamin C. Whether you choose to get your iron from animal sources such as red meat or plant sources such as spinach, iron is much better absorbed by the body with vitamin C. Add a glass of orange juice to your meal or toss some tomatoes onto your spinach salad.
Food-and-drug interactions. Always pay close attention to potential food interactions that may occur with any prescription or over-the-counter medications. Grapefruit, for instance, interacts with many medications used to treat high blood pressure, high cholesterol or allergies and can inhibit the effectiveness of these drugs.

Grapefruit Juice Can Interact With Medicines! Medical Author:

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Medical and Pharmacy Editor:

Jay W. Marks, MD

http://www.medicinenet.com/grapefruit_juice_and_medication_interactions-page2/views.htm

Wheat fiber, phytates and iron absorption.

Scand J Gastroenterol Suppl. 1987;129:73-9.

Hallberg L

http://www.ncbi.nlm.nih.gov/pubmed/2820048

Phytate in foods and significance for humans: food sources, intake, processing, bioavailability, protective role and analysis.

Mol Nutr Food Res. 2009 Sep;53 Suppl 2:S330-75. doi: 10.1002/mnfr.200900099.

Schlemmer U¹, Frølich W, Prieto RM, Grases F.

http://www.ncbi.nlm.nih.gov/pubmed/19774556/

Alkaline Diets
By Sonya Collins, Reviewed by Michael Dansinger, MD on November 26, 2013