I spend most of my time steering people away from supplements. B12 is the clearest exception in the whole library.
What it does
B12 is needed to make red blood cells, to build and maintain the myelin sheath around your nerves, and for DNA synthesis. A shortfall affects blood and nervous system both.
Why it's different from every other nutrient here
B12 is made by bacteria, not by plants or animals. Animals accumulate it; plants do not. There is no reliable plant source — not spirulina, not nutritional yeast unless it's fortified, not fermented foods, not mushrooms. The compounds in some of those are analogues that don't do the job and may interfere with the real thing.
If you eat little or no animal food, you need a supplement or reliably fortified foods. This isn't a preference; it's a fact about where the molecule comes from.
Where it comes from in food
Clams and liver are extraordinarily high. Beef, salmon, tuna, dairy and eggs all contribute. Fortified plant milks, fortified nutritional yeast and fortified cereals are the plant-based routes.
Absorption gets harder with age
B12 needs stomach acid and a protein called intrinsic factor to be absorbed. Both decline with age, which is why deficiency is common in older adults even when intake looks fine on paper.
Certain long-term medications also reduce absorption — metformin, and acid-reducing drugs including proton pump inhibitors. If you take either long term, this is worth raising with your doctor.
Why it matters that you catch it
Low B12 causes tiredness and anaemia, but also neurological symptoms: pins and needles, numbness, memory and balance problems. Nerve damage from prolonged deficiency can become permanent. Folate supplements can also mask the blood signs while nerve damage continues quietly underneath, which is why B12 is tested rather than guessed at.
Supplementing
It's cheap, well studied, and there's no established toxicity at ordinary doses — your body clears what it doesn't use. Ask your doctor about testing and the right dose. If absorption is the problem rather than intake, injections may be needed instead of tablets, which is again a medical decision.
This is general nutrition education, not medical advice, and it isn't intended to diagnose, treat, cure or prevent any condition. If you're pregnant or breastfeeding, taking medication, or managing a diagnosed condition, talk to your doctor or pharmacist before making changes.
Written by Mellissa Wallace, Registered Holistic Nutritionist, Okanagan BC.
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