Vitamin B12: the one supplement every plant-based eater needs

If you remember one thing about plant-based eating, make it this: you need a reliable source of vitamin B12. It is the only nutrient that a varied, whole-food plant diet cannot supply on its own.

Why B12 matters

Vitamin B12 keeps your blood and nervous system healthy and helps make DNA. Without enough, you can develop a type of anaemia and, over time, nerve damage that may not fully reverse.

Why plants do not provide it

B12 is made by bacteria, not by plants or animals. Animals get it from their food or gut bacteria, which is why the NIH notes that "only animal foods have vitamin B12 naturally". Spirulina, seaweed, mushrooms and fermented foods are not reliable sources.

How much you need

The NIH recommends 2.4 micrograms a day for adults, and a little more during pregnancy and breastfeeding. Your body absorbs only a small share of large doses, which is why supplements often contain much more than 2.4 mcg.

Signs of running low

Your body stores B12, so deficiency can take a year or more to appear. That is exactly why it is easy to miss. Signs include tiredness, weakness, pale skin, tingling or numbness in the hands and feet, balance problems and trouble with memory. If you notice any of these, see a doctor and ask for a blood test. Do not wait.

How to cover it

• A supplement. The simplest option. Take it daily or weekly, as a pharmacist or doctor advises.
• Fortified foods. Some plant milks, breakfast cereals and nutritional yeast have B12 added. Check the label, and eat them every day if they are your only source.
• Test. A blood test after a few months, then once a year, confirms you are covered.

Who needs extra care

Pregnant and breastfeeding women, babies and children of plant-based parents, and older adults (who absorb B12 less well) should plan their B12 with a doctor. Some medicines, including metformin and long-term antacids, also reduce absorption.

We cook your meals. The B12 is your responsibility. It is the one step that makes everything else on a plant-based diet safe.