Kristen Zaier, ​​Plant-Based RD

References used for all of the nutrient pages can be found at the bottom of the Nutrition Facts page. Click here.

Fortified Food Sources of B12


Food

B12 Content (mcg)

Soymilk, 1 cup (unsweetened, Wildwood)

3

Total cereal, 1 cup

8

Raisin bran, 1 cup (Kellogg)

2.5

Bite sized frosted wheat, 1 cup (365)

1.5

Nutritional yeast, 1 tsp (Red Star VSF)

0.9

Cultured coconut milk, 6 oz (Trader Joes)

1.8

Meatless pepperoni slices, 10 (Yves)

0.6

Meatless beef burger, 1 patty (Yves)

2.4



​Deficiency Symptoms


  • Anemia
  • Smooth tongue
  • Fatigue
  • Confusion
  • Tingling in the hands and feet
  • Paralysis


​Toxicity Symptoms


  • Large amounts of B12 seem to be non-toxic

  • Excess B12 is excreted in the urine


How to Assess Status


  • Serum B12 is often ordered but the preferred test is a urine or blood test for methylmalonic acid (MMA)

  • Ask your physician for a MMA test if you are concerned about your B12 intake


Notes


  • The RDA for adults is 2.4 mcg/d but there is some new evidence that 4-7 mcg/d is optimal

  • The study that led to the 2.4 recommendation is over 50 years old and was based on only 7 subjects


Links


Dr. Michael Greger has a great set of videos on B12. Please check them out! 


  How Much B12 Do I Need?


  • RDA for Adults: 2.4 mcg/d

  • Upper Safe Limit for Adults: Not Determined


Why Do I Need B12?


  • B12 is needed to make red blood cells

  • Maintain nerve cells

  • Activate folate

  • ​Break down some fatty acids and amino acids


Plant-Based Sources 


  • There are NO unfortified plant-based sources for B12

  • B12 is produced by bacteria lining the gut of humans and animals

  • The B12 that our microbes produce is not absorbed because it is made in the colon beyond the absorption site

  • Our plant eating ancestors likely consumed enough B12 through plants and fresh water sources that were contaminated with B12 producing bacteria

  • Today we have a very sanitary water and food supply so the safest way to get B12 is through fortified plant foods or supplements

  • ​You may see claims that foods like tempeh, seaweed, miso and bean sprouts naturally contain B12 but these foods contain a B12 analog that is not active in our bodies

  • If you are following a strict plant-based diet it is critical that you get a regular and reliable source of B12 through fortified foods or supplements

  • Many foods are fortified with B12 including some soymilks, breakfast cereals, non-dairy yogurts, nutritional yeasts and meat substitutes

  • Shoot for 3 servings of fortified foods daily or consider taking a supplement of either 250 mcg each day or 2500 mcg once a week

  • These recommended amounts for supplements are set high to account for absorption rates  


Vitamin B12