Preheat oven to 350°F.
Mix together flour, flaxseed, oat bran, baking soda, baking powder, salt and cinnamon in a large bowl. Stir in carrots, apples, raisins (if desired) and nuts (if desired).
Combine milk, eggs, honey and vanilla in a separate bowl. Pour liquid ingredients into dry ingredients. Stir until batter is moist. Do not overmix.
Fill muffin cups 3/4 full. Bake at 350°F for 15-20 minutes. Enjoy!