Preheat the oven to 400°F [not convection] and either grease 12 muffin cups or line with liners.

Mix the buttermilk and wheat bran, then set aside to soak.

In a separate medium bowl, combine the whole wheat flour, oat bran, flaxseed, baking powder, baking soda, cinnamon, and protein powder, then set aside.

In a large mixing bowl, add egg white, sugar, oil, banana, and vanilla and mix until well combined.

Gently stir the dry ingredients into the banana mixture. Then fold in the soaked wheat bran and buttermilk mixture and make sure not to leave any lumps of bran unmixed.

Fold until just combined, leaving a few lumps remaining. Then fold in the blueberries, being careful not to overmix the batter.

Pour the batter into the prepared muffin pan and bake for 15-22 minutes, or until a toothpick inserted into the center comes out with a few crumbs clinging to it. Cool for 5 minutes in tins, then turn out onto a rack to cool completely.