Preheat oven to 180°C and grease or line a muffin tray.
In a large bowl, sift together the flour, bicarb, baking powder, salt, and sugar. Stir in the bran.
In another bowl, whisk together the eggs, oil, and buttermilk.
Combine the wet and dry ingredients, mixing gently until just combined. Fold in raisins or dates if using.
Spoon into muffin cups, filling each about two-thirds full.
Bake for 20–25 minutes until risen and golden brown. Test with a skewer — it should come out clean.
Allow to cool slightly before serving.