Vitamin B12

What plants do not provide

The only vitamin that no plant makes — not vegetables, not grains, not seaweed.

Spirulina, chlorella and nori contain inactive ANALOGUES, which can also distort a blood test. A diet without animal products requires a supplement — it is the one point on which plant-based nutrition does not argue. Some nutritional yeasts and plant-based drinks are fortified with B12: the label says so.

Effects and benefits

The only vitamin no plant makes. It forms red blood cells and maintains the nerves; its deficiency can damage the nerves lastingly, and takes years to show, because the liver keeps reserves.

Vitamin B12 contributes to normal red blood cell formation, to the normal functioning of the nervous system, to normal psychological function, to normal homocysteine metabolism and to the reduction of tiredness and fatigue (Regulation 432/2012).

The liver stores 2 to 5 mg, enough to last several years: a deficiency sets in silently, then causes anemia, fatigue, tingling, sometimes memory trouble, and nerve damage is not always reversible (NIH).

By sex and age: EFSA sets the adequate intake at 4 µg a day for an adult, 4.5 during pregnancy and 5 during breastfeeding (EFSA, 2015). With age, the stomach produces less acid, and 10 to 30% of people over fifty absorb food B12 poorly (NIH); some medicines for acidity or diabetes also lower it.

It is produced by BACTERIA, not by plants nor by animals: the latter only accumulate it. Our own colon bacteria make it, but too far downstream for us to absorb it.

Sources: EU Regulation 432/2012 · EFSA, 2015 · National Institutes of Health