There are lots of ways to reduce nitrate aside from reducing foods.
These include growing macroalgae (and ATS), organic carbon dosing (pellets, vinegar, vodka, etc), several types of denitrators, skimming, deep sand and rock, water changes, etc.
IMO, it is generally good advice to use several of those at once.
These have more:
The “How To” Guide to Reef Aquarium Chemistry for Beginners,
Part 4: What Chemicals May Detrimentally Accumulate
http://reefkeeping.com/issues/2007-09/rhf/index.php
Phosphate and the Reef Aquarium
http://reefkeeping.com/issues/2006-09/rhf/index.php
Nitrate in the Reef Aquarium
http://www.advancedaquarist.com/issu...t2003/chem.htm
Reef Aquarium Water Parameters
http://www.reefkeeping.com/issues/2004-05/rhf/index.htm