Vitamin B12: animal foods, fortified products and plant-based choices

B12 is essential for the nervous system and red blood cell formation. A shortfall often sets in slowly, since the body has reserves. Its signs (fatigue, tingling, balance or concentration problems) are not very specific: they warrant a consultation but don't prove a deficiency.

Anses (the French food safety agency) concluded in 2025 that vegetarians on average have a less favorable status for B12, iron, iodine, and vitamin D than non-vegetarians, and that meeting B12 needs is particularly difficult for vegans.

A vegetarian diet that keeps eggs and dairy isn't in the same situation as a vegan diet. But the name of the diet isn't enough: actual meals are what matter. A vegetarian who rarely eats eggs or dairy can have a low intake.

B12 added to fortified foods and supplements is already in free form: it doesn't need to be released from proteins by stomach acid, unlike the B12 in food.

Certain algae or fermented products are presented as plant sources of B12. Many plant sources only provide traces or contain analogs inactive in humans, sometimes called pseudo-vitamin B12, which might even interfere with the absorption of the real vitamin. They shouldn't serve as a reference source.

Nutritional yeast only contains B12 if it has been fortified. Here again, only the label can settle the question.

Plant-based drinks, breakfast cereals, nutritional yeasts, or meat substitutes can be fortified, but not systematically: two products in the same line can differ. The words "plant-based," "organic," or "natural" say nothing about B12.

A fortified product used occasionally doesn't play the same role as one eaten every day. To find out if intake is sufficient, take stock of a typical week: animal sources, fortified products actually eaten, and days with no source at all.

If no animal or fortified source is eaten regularly, a B12 supplement becomes necessary. This is the case for most vegans. The form, dose, and frequency depend on the product and the person; it's better to discuss this with a doctor, pharmacist, or dietitian rather than reuse a dose example found online.

A supplement helps prevent insufficient intake. It doesn't replace the diagnosis or treatment of a confirmed deficiency, which calls for medical follow-up: see the article B12: testing, supplementation and risks.

• Believing that algae, unfortified yeast, or a fermented product covers needs.
• Comparing content without checking the serving size.
• Forgetting that a fortified product's recipe can change.
• Thinking an occasional meal makes up for the lack of a regular source.
• Reducing a food's value to its B12 content alone, forgetting protein, calcium, salt, or added sugars.