Port of Subs publishes a full 479-entry ingredient database, and nine of its eleven breads list a seed oil - White and Wheat both use soybean shortening and the sliced breads list soybean oil outright - while the mayo is soybean oil, so a standard sub carries seed oil in the bread before any filling goes on it. 366 of 435 food entries also carry at least one additive, including azodicarbonamide in the sliced white and wheat bread.
Rated from Port of Subs' own ingredient database (nutritionix.com/port-of-subs/ingredient-search/premium, 329,399 bytes, 479 entries, 435 after excluding drink-named rows), read 2026-08-26. Seed oils: 103 of 435 name one outright - soybean 64, canola 24, sunflower 21, corn 11, cottonseed 2 - and 132 counting generic Vegetable Oil, most of which spells itself out as (Corn And/Or Canola). The bread decides it. White Bread and Wheat Bread both list soybean shortening; Sliced White, Sliced Wheat, Sliced Wheat Berry, Sliced Pumpernickel and Jalapeno Cheddar all list soybean oil; both wraps do too. Only Sourdough and Sprouted Wheat Bread escape. Mayo is Soybean Oil, HFCS and EDTA. No swap offered. Additives: 366 of 435. Clean: 63 entries - the produce, avocado, egg, tuna, provolone, swiss and the vinegar-and-oil dressing.