This is the one nutrient the evidence is blunt about: plant foods are not a reliable source, so vegans need a supplement or fortified foods. Full stop.
Vegan Brief·Evidence last reviewed July 2, 2026
This is a summary of the cited evidence, not medical advice.
RDA (adults)2.4 mcg/day
Reliable vegan sourceSupplement or fortified foods
The ruleNot optional
01
The short version
B12 is the vitamin where the honest answer and the reassuring answer are the same answer. Vegans need a reliable source, and plant foods are not it. Here is the US government's fact sheet, which is public domain, saying so plainly.
Primary source 01 / 04
Vegans who consume no animal products and vegetarians who consume some animal products (e.g., dairy products, eggs, or both) but not meat have a higher risk of developing vitamin B12 deficiency because natural food sources of vitamin B12 are limited to animal foods
The same fact sheet gives the fix in the next breath.
Primary source 02 / 04
Consumption of foods fortified with vitamin B12 (such as fortified nutritional yeasts) as well as vitamin B12 supplements can substantially reduce the risk of deficiency
The Academy of Nutrition and Dietetics is the largest body of registered dietitians in the United States. Its 2016 position paper is direct about which plant foods do not count.
Primary source 03 / 04
Vitamin B-12 is not a component of plant foods. ... Fermented foods (such as tempeh), nori, spirulina, chlorella algae, and unfortified nutritional yeast cannot be relied upon as adequate or practical sources of B-12.
Vegans must regularly consume reliable sources, meaning B-12-fortified foods or B-12-containing supplements, or they could become deficient, as shown in case studies of vegan infants, children, and adults.
So the two most authoritative sources agree, and neither hedges. A B12 supplement or reliably fortified foods, every day. It is cheap, it is settled, and it is the least dramatic thing on this whole page.
Vegan diets in pregnancy and childhoodThis is the page to get right, so it is the page with the most hedging. The dietitians' body says a planned vegan diet works at every life stage. The same sources say B12 is not optional.
Iron on a vegan dietPlants have iron, just the kind your body absorbs less easily. The government fact sheet quantifies exactly how much less, and what raises the odds in your favor.
Riboflavin (B2) on a vegan dietRiboflavin is a quiet one: no dramatic deficiency story, just the fact that dairy and eggs carry a lot of it. Take those away and the NIH puts vegans on the watch list, which fortified foods and a few staples handle.
Choline on a vegan dietCholine is the nutrient nobody talks about until pregnancy, and the richest sources are animal foods. The plant list is real but shorter, and most people of any diet already fall short.
Folate on a vegan dietFolate is the one B vitamin plant eaters rarely have to think about. The name comes from foliage, and the diet is built on exactly that.
Is Vitamin B12 (cobalamin) vegan?Is it vegan? · Here is the reassuring one. The B12 in your supplement or fortified plant milk is grown by bacteria, not squeezed from an animal, and every vegan needs a reliable source of it.
Is Nutritional yeast vegan?Is it vegan? · Nutritional yeast is vegan. Yeast is a fungus, not an animal, and nooch is grown on a sugar medium and then deactivated by heat.
Frequently asked
Do vegans really need to supplement B12?
Yes. The NIH Office of Dietary Supplements states that natural food sources of vitamin B12 are limited to animal foods, and the Academy of Nutrition and Dietetics states that vegans must regularly consume B12-fortified foods or B12-containing supplements or they could become deficient.
Can I get B12 from nutritional yeast or fermented foods?
Only if the nutritional yeast is fortified with B12. The Academy of Nutrition and Dietetics says fermented foods such as tempeh, nori, spirulina, chlorella algae, and unfortified nutritional yeast cannot be relied upon as adequate or practical sources of B12.
The primary sources
The documents this page quotes. Read them yourself.
