Preheat oven to 400°F
In a medium sized pan boil the water, remove from heat and add buttermilk and baking soda. Stir until combined
In a separate bowl, using a hand mixer cream together the shortening, sugar, eggs, and salt
In separate bowl mix together the flour, All Bran, and bran flakes
Add approx. ⅓ of the milk mixture to the creamed shortening/sugar mixture and mix until combined.
Add approx. ⅓ of the dry ingredients to the creamed shortening/sugar and mix until combined. Continue alternating between the milk and dry ingredients until it is all combined.
Fill prepared muffin tins ⅔ full with the batter and bake for 20 minutes. Cool baked muffins on a cooling rack and store in an airtight container for up to 5 days.