Nutrition
Do fortified cereals replace a B12 supplement?
Short answer
They can, but only if you are consistent. The Vegan Society considers fortified foods eaten 2–3 times a day, giving at least 3 µg of B12 in total, to be enough. One bowl of cereal in the morning is not. For most people a supplement is simpler and more reliable (for example at least 10 µg daily or 2000 µg once a week).
Why consistency? From a single meal the body absorbs only about 1.5–2 µg of B12, and only about 1% of a large dose. That is why several small portions a day (for example a plant drink with about 1 µg of B12 per serving, three times a day) work about as well as one 10 µg tablet.
Check the label for B12 per serving – amounts vary between brands, and organic products are usually not fortified. If three servings a day are hard to keep up, take a supplement.